SECTION 4: NUTRIENTS
Section 4: Nutrients
Resource management
Content
Elaboration
Nutrients and their effect on the
health and development of
individuals
An in-depth study of nutrients, their
function and the effect on the health
and development of individuals at
different life stages/in special
circumstances:

pregnancy and lactation

infants and young children

teenagers

adults

elderly

vegetarians

weight reduction

sports performance
Reference should also be made to sections on main nutrients,
micronutrients, antioxidants and dietary diseases
Pregnancy and lactation
A varied diet containing adequate amounts of energy and nutrients is essential
before a woman becomes pregnant (conceives), during pregnancy and if she
breastfeeds (lactation). The mother’s diet influences the health of the baby in
the short term and perhaps even in the long term.
Preconception
Having a healthy body weight is important before pregnancy. Being
underweight can affect fertility, making it more difficult to conceive. It can
also increase the chance of the baby having a low birth weight, which can
increase the risk of ill-health in early and later life. Being very overweight
can also affect fertility and increases the risk of complications , such as high
blood pressure, infections and diabetes, during pregnancy.
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Folate/folic acid
The vitamin folate is particularly important before conception and during the
first 12 weeks of pregnancy. Extra folate at this time reduces the risk of
having a baby with a neural tube defect, such as spina bifida.
All women of child-bearing age who may become pregnant are advised to
take daily supplements (400 micrograms) of folic acid (the manufactured
form of folate), as it is difficult to achieve the extra folate needed through
diet alone. This is because the vitamin is important at a time when many
women do not realise that they are pregnant. A woman who has already had a
baby with a neural tube defect may be advised by her doctor to take a larger
supplement (for example 5 mg/day). It is also important to consum e foods
that are naturally good sources of folate, eg green vegetables, oranges, and
foods that have been fortified with folic acid , such as some breads and
breakfast cereals.
During pregnancy
Contrary to the popular phrase ‘eating for two’, most pregna nt women do not
need to double their food intake. In fact, it is only during the latter part of
pregnancy that some additional energy is needed; an increase of 0.8 MJ or
200 kcals a day in the last 3 months of pregnancy is recommended, although
the needs of individual women will vary, depending on how active they are
(see below). However, an expectant mother requires a healthy and varied diet
to provide her and her growing baby with the full range of nutrients.
Weight gain
A weight gain of 12.5 kg in women of normal pre-pregnant weight is
associated with the lowest risk of complications during pregnancy and labour.
In practice, however, there is a wide range of weight gains in individual
women who have normal and healthy pregnancies, with average weight ga ins
of between 11 and 16 kg.
During pregnancy a woman’s nutritional needs increase because the diet must
provide sufficient energy and nutrients:
 to meet both the mother’s usual needs and provide extra for the growth of
the breasts, uterus and placenta
 to meet the needs of the growing foetus
 for the mother to lay down stores of nutrients to help the growth of the
foetus, and for lactation.
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Nutrients and oxygen pass from the mother’s blood to the foetus from the
placenta, via the umbilical cord.
In the last 3 months of pregnancy, the body has a slightly greater requirement
for energy. This is a time of rapid growth and movement for the growing
baby. The estimated average requirement for energy (EAR) increases during
the last 3 months of pregnancy by an average of 0.8 MJ (200 kcal) per day. At
this time a woman’s energy expenditure from physical activity is usually
reduced. If a mother’s food intake is very low at this stage and if her fat
stores are low, the foetus grows more slowly and the baby may hav e a low
birth weight. This may increase the risk of heart disease, diabetes and raised
blood pressure many years later, in adult life.
It is important at this stage not to eat too many energy foods as weight gain
may occur because of reduced activity at t his stage in pregnancy.
A diet high in fat and/or sugar may result in the mother gaining weight during
pregnancy, which may be difficult to lose after the birth and so she may have
long-term weight and associated health problems such as varicose veins,
diabetes, arthritis, etc.
Gaining too much weight may increase her risk of high blood pressure , which
in turn increases the risk of pre-eclampsia.
Poor diet during pregnancy may lead to obesity problems for the baby in later
life. Children are more likely to become overweight adults if their parents are
obese.
Carbohydrates and fats
The source of energy should mainly be supplied by carbohydrates.
Constipation can be a problem in pregnancy. If it is, more non-starch
polysaccarides (NSP) should be taken along with increased fluid intake and
gentle exercise such as walking or swimming. A diet rich in saturated fats
during pregnancy has been linked with later development of breast cancer in
children.
Omega-3 fatty acids are required for the development of th e foetal nervous
system and are especially important during the last 3 months of pregnancy.
Iron
The mother must have enough iron during pregnancy to supply her own body
and to provide the growing baby with a store of iron for the first 4 months
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after birth. Breast milk and cow’s milk are both poor sources of iron, so a
store of iron is essential. A mother’s haemoglobin count is checked regularly
during pregnancy.
Iron needs are increased during pregnancy to allow for the growth of the
placenta and foetus. Consequently it is recommended that pregnant women
consume plenty of foods containing iron such as red meat, fortified breakfast
cereals, pulses, breads and green vegetables eaten as part of a normal diet.
However, there is also an iron saving because of the absence of menstruation
(periods) and an increase in iron absorption during pregnancy, so most
pregnant women do not need extra iron during pregnancy. However, some
groups of women (eg young women aged 15–18 years) typically have low
intakes of iron before becoming pregnant, and are at risk of developing
anaemia. Iron-deficiency anaemia during pregnancy can increase the risk of
the baby having a low birth weight and developing iron -deficiency anaemia
during the first year or two of life. These women will be prescribed iron
supplements and may also be given dietary advice to ensure that their diets
contain adequate amounts of all nutrients.
Protein
A little additional protein may be required for the development of the foetus’s
body cells. Amino acids are actively transported across the placenta to the
foetus
Too much protein, however, could contribute to weight gain.
Folic acid
Women are advised to ensure that their diet contains adequate supplies of
folic acid before becoming pregnant and during pregnancy, especially the
first 3 months of pregnancy. Folic acid reduces the risk of babies being born
with neural tube defects such as spina bifida. It is required for the
development of the brain and nervous system in the baby .
Calcium, phosphorous and vitamin D
The baby’s bones are supplied with calcium provided by the mother’s diet. A
diet low in calcium may result in the formation and calcification of the baby’s
bones being affected.
It is important that calcium intake is maintained to ensure tha t calcium
deposits from the mother’s bones and teeth are not used for this purpose.
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A diet low in vitamin D may result in poor calcium absorption and as a result
the formation and calcification of the baby’s bones may be affected . A diet
low in vitamin D can lead to low birth weight and tetany in the baby and
osteomalacia in the mother.
Vitamin C
To enable iron to be absorbed, foods rich in iron and vitamin C are required.
Vitamin C is also required for the baby’s tissue formation.
Vitamin A
Vitamin A is essential for good health. However, large intakes during early
pregnancy have been linked to birth defects. Women who are pregnant, or
who might become pregnant, should not take vitamin A supplements unless
they are advised to do so by a health profes sional. Liver and liver products
(eg paté) may contain large amounts of vitamin A, so these should also be
avoided.
Other factors to be considered during pregnancy
Alcohol
Drinking alcohol during pregnancy can damage the unborn child, so pregnant
women are advised to avoid alcohol.
Drinking alcohol during pregnancy, especially in large quantities
(alcoholism), may in some cases result in foetal alcohol syndrome . This may
affect growth, brain development, mental retardation and organ defects in the
unborn child.
Caffeine
The Food Standards Agency (FSA) advises pregnant women to limit the
amount of caffeine they consume to no more than 300 mg a day (around four
cups of coffee). High levels of caffeine can result in babies having a low birth
weight, or even lead to pregnant mothers miscarrying. Caffeine is added to
some soft drinks and energy drinks, as well as occurring naturally in foods.
Smoking
Pregnant women should not smoke. One effect of smoking may be to reduce
the flow of blood to the placenta and so reduce or slow down the supply of
nutrients to the foetus and affect foetal growth. This may result in a low birth
weight.
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Fish
The population guideline recommendation for fish consumption is at least two
portions of fish per week, one of which sho uld be oily fish. This
recommendation also applies to pregnant and breastfeeding women, but they
should limit oily fish to up to two servings per week. Also, these groups of
women should avoid the fish marlin, swordfish and shark because of potential
exposure to methylmercury. The FSA also advises pregnant women that the
amount of tuna eaten should be limited to no more than two tuna steaks per
week or four medium-sized cans a week. This is again because tuna may
contain mercury, which at high levels can ha rm a baby’s developing nervous
system. The basis of these recommendations is that the consumption of fish,
particularly oily fish, confers significant health benefits in terms of
protection against heart disease. This is attributed to the long -chain n-3
(omega-3) polyunsaturated fats, of which oily fish is a rich source. These
types of fatty acid are also required for the development of the central
nervous system in the foetus and young infant, so are important for both
pregnant and breastfeeding women. However, the FSA has set a maximum
limit on oily fish consumption due to the risk of exposure to pollutants such
as dioxins and polychlorinated biphenyls, which have been found in oily fish.
Arachidonic acid (AA) and docosahexaenoic acid (DHA) are long-chain
polyunsaturated fatty acids that are important for foetal development of the
brain, nervous system and retina, and so an adequate supply of them is
essential during pregnancy. Whereas AA can be synthesised from another
fatty acid, linoleic acid, DHA can only be synthesised to a limited extent,
therefore dietary DHA is particularly important and the best source is oily
fish, in which DHA is available pre-formed, although it can also be obtained
from foods fortified or enriched with DHA.
Physical activity
Staying physically active during pregnancy is important to promote general
health and help to alleviate common complaints during pregnancy such as
backache and constipation. Useful activities include swimming, some forms
of yoga, toning and stretching, which can be done at any stage of pregnancy.
Harmful bacteria
Listeriosis is a rare flu-like illness caused by bacteria called Listeria
monocytogenes. Listeriosis in pregnancy may cause miscarriage, still -birth or
severe illness in the newborn baby. Although it is rare in this country,
pregnant women are advised to avoid those foods where high levels of the
bacteria have occasionally been found, for example paté and blue -veined and
soft cheeses such as Brie and Camembert. For similar reasons, it is
emphasised that pregnant women re-heat ready-cooked meals (particularly
those containing poultry) until they are piping hot and that they wash fruit
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and vegetables well, especially if they are to be eaten raw (which is also the
advice given to the general population).
Toxoplasmosis is an illness caused by a parasite found in cat faeces. The
parasite can also be present in raw meat and occasionally goat’s milk. The
illness can, in rare cases, be passed to the unborn baby via its mother,
resulting in a range of problems, some of them serious. As a safeguard,
pregnant women should not eat raw or undercooked meat, unpasteurised
goat’s milk or goat’s cheese, or unwashed raw fruit and vegetables. Good
food hygiene practices should be followed in the kitchen and contact with cat
litter trays or soil that may have been fouled by cats should be avoided by
wearing gloves.
Salmonella poisoning is particularly undesirable during pregnancy, although
it is not likely to have a direct adverse effect on the baby. As a precaution,
pregnant women should avoid eating raw eggs or food that contains eggs that
are raw or partially cooked. Eggs should be cooked until both the white and
yolk are solid. Raw meat and chicken can also be a source of salmonella
bacteria. All meat, especially poultry, should be thoroughly cooked and it is
important to avoid contamination of other foods by washing hands after
touching raw meat and by preventing raw meat and poultry from touching or
dripping onto other food (eg in the fridge), especially that which is already
cooked or will be eaten raw.
Lactation
Advice states that breastfeeding is the best method of feeding for babies. A
varied diet is important whilst breastfeeding to ensure a sufficient intake of
all nutrients needed by both the mother and the baby.
The production of milk requires a supply of nutrients. Some, such as energy,
will be partly met from the mother’s stores. Breastfeeding mothers may also
be advised to take Vitamin D supplements to ensure that intake reaches at
least 200 International Units (IU) each day.
Advantages of breast feeding
1.
Psychological benefits
 Mother bonds with child and establishes a close emotional
attachment to the child.
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2.
Health benefits
 Breast milk contains antibodies and other protective substances that
provide specific protection for the child and encourage growth and
development of infant tissues and organs.
 The baby is less likely to become overweight because the baby
decides when it is full and stops feeding.
 No likelihood of allergies to breast milk.
 Greater resistance to infection, especially gastrointestinal infection
and diarrhoea.
 Medical evidence suggests that babies who are breastfed have a
lower risk of developing asthma.
 Breastfeeding may help the mother to loose excess fat stores gained
during pregnancy.
 Medical evidence suggests that women who breastfeed and breastfed
babies have a lower risk of developing breast cancer.
 Breast milk contains essential fatty acids, ie omega-3 and omega-6,
which assist in the brain development of the baby.
3.
Hygiene benefits
 Human milk is germ free.
 Less chance of stomach upsets through unhygienic preparation of
foods.
4.
More convenient and labour saving
 No preparation time is needed and there is less hassle.
 No equipment to sterilise.
 Possible to feed baby on demand and quickly if necessary.
 Cannot be prepared incorrectly.
5.
Easier to digest and suitable for all babies
 Easier to digest therefore less chance of nappy rash and stomach
upsets.
 Milk contains all the energy and essential nutrients needed by babies
in the correct proportions.
6.
More economical
 No extra equipment is needed, no milk formula to buy – breast
feeding is free.
 Always at the correct temperature so no heating is needed.
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Infants/young children
Key points
 Encouraging pre-school children to eat a healthy, varied diet will provide
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all the nutrients they need for healthy growth and development and help to
establish good eating habits for life. Poor eating habits may be difficult to
change in later life.
Poor diet in childhood can lead to health problems in later life.
Young children who are growing and are usually very active have high
energy and nutrient requirements in relation to their size.
Young children have small stomachs and may not be able to obtain all the
energy and nutrients they need if their diet contains too much fibre. Such
diets can sometimes reduce the amount of minerals they can absorb, such
as calcium and iron.
By the time they are 5 years old, children should be eating family food and
consuming a varied diet.
A healthy diet will help children avoid becoming overweight or obese.
Regular meals, consisting of small attractive servings and a pleasant
atmosphere, are important in encouraging young children to eat.
Include the use of naturally brightly coloured foods in meals and snacks.
Introduce new tastes and textures gradually.
Use food products that are additive free.
Dietary guidelines
Energy
A variety of foods should be introduced so that a range of nutrients is
obtained.
 Children’s energy requirements increase rapidly because t hey are growing
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quickly and becoming more active. They have a high energy requirement
for their size. To achieve this energy intake, foods which are high in
energy (and also rich in nutrients) should be eaten as part of small and
frequent meals for younger children, who do not have large enough
stomachs to cope with big meals.
Some complex carbohydrate foods such as wholemeal bread and potatoes
should be included to supply energy.
Do not include too much NSP-rich food as this will be very filling and
children will be unable to eat enough food to supply all the other nutrients
they need.
Avoid giving children too many foods high in fat and fried foods . As
children approach school age their fat intakes should be in line with the
Scottish dietary recommendations.
Choose lower fat versions of some dairy produce , eg yoghurts.
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 Whole milk is recommended for children over the age of 12 months as a
main drink as it is a rich source of a number of nutrients. Semi -skimmed
milk can be introduced after the child is 2, as long as the rest of the diet
provides enough energy. Skimmed milk is not suitable for children under 5
years of age, as it does not provide enough energy and vitamin A for the
growing child.
 Avoid too many sugary foods as this will contribute to obesity a nd tooth
decay. Avoid giving sweets as a reward and avoid sugar-coated breakfast
cereals.
Protein
 Protein is required for the growth of new body cells and tissues as well as
the repair of damaged tissues through play, falls , etc. Young children will
also be going through a growth spurt.
Calcium, phosphorus and vitamin D
 Calcium, phosphorous and vitamin D are required to form and maintain
strong bones and teeth.
 Young children need plenty of calcium in their diets for healthy bones and
teeth. Dairy products such as milk, cheese and yogurt are good sources of
calcium. Other foods such as white bread, dark green leafy vegetables,
pulses (eg baked beans) and fortified cereals can also contribute to calcium
intake.
Iron
 Supply iron-rich foods to prevent anaemia, eg add dried fruits to breakfast
cereals. Red meat is the best source of easily absorbable iron and can be
offered to children from 6 months of age. Iron -rich foods, such as liver and
red meat, may not be popular with young children, so other ways of
providing this nutrient must be found. Children who are vegetarian must
have alternative sources of iron, such as green vegetables and pulses.
Other useful sources include bread and some breakfast cereals. Iron from
plant sources is less well absorbed than iron from animal sources but can
be improved by consuming vitamin C-rich foods or drinks (such as orange
juice) with a meal.
Vitamin C
 Vitamin C is required to assist the absorption of iron and prevent anaemia,
particularly since the volume of blood increases during the early years.
 Vitamin C is necessary for healing wound/sores – children may be active
and be more at risk of injury.
 Encourage the eating of fruit and vegetables as a low fat and sugar snack.
Serve vegetable sticks as snacks and give fresh and dried fruits as snacks
in order to supply vitamin C.
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Sodium
 Avoid salty foods as this encourages a liking for salt in the diet. Avoid
salty snacks and a lot of processed foods in the diet.
Teenagers
General points
 Adolescence is a period of rapid growth, body development and a high
level of activity and as a result nutrient requirements increase at this stage .
 Not all teenagers have high activity levels and this must be reflected in the
energy intake if obesity is to be avoided.
 Many teenagers have a tendency to ‘graze’ on snack or fast foods so it is
essential to encourage a healthy diet.
 Food habits during teenage years will affect health in later life.
 Smoking is extremely detrimental to bone health and alcohol should only
be drunk in moderation, as it is a toxin to bone cells. Teenagers should
establish a regular exercise programme as exercise can increase and
stimulate bone density.
Dietary guidelines
In addition to the normal functioning of nutrients, teenagers have increased
requirements for the following:
Energy, especially if participating in games and sports. Males need more
energy than females because:
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(b)
(c)
they tend to have a larger body size than females
they may be more active than females and so need a greater amount of
energy to supply the cells
they tend to be more muscular than females and so have a greater need
for energy sources to the muscles.
Energy should be supplied in the form of complex carbohydrates. Vitamin B
complex is required to release energy from carbohydrate food s.
Protein
Teenagers require protein for their rapid growth spurt and to repair damaged
tissues, especially if a lot of sports are played.
Calcium
About 45% of the adult-sized skeleton forms during adolescence, so plenty
calcium and phosphorous foods should be eaten to ensure the proper
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formation of bones and teeth. Vitamin D will promote the absorption of
calcium.
Iron
For both males and females, iron requirements increase as blood volume
expands throughout growth. Iron is particularly important in e arly
adolescence for girls, to prevent anaemia developing when menstruation
starts. Teenagers may be susceptible to anaemia if diet is poor.
Sodium
Low intake may result in muscle cramps, eg if the teenager gets dehydrated.
Excess can cause high blood pressure as the result of the expansion of
extracellular fluid volume. This is particularly dangerous in later life, and it
is important not to start bad habits at this age.
Phosphorus
This is an essential component of all bones along with calcium to ensur e
strong bones and teeth are developed and maintained during teenage years. It
is also vital in the repair of bones, eg after an injury.
Vitamin C
Vitamin C is required to assist the absorption of iron and prevent anaemia,
particularly since the volume of blood increases during the teenage years.
Plenty of fruit and vegetables should be eaten to provide this antioxidant
vitamin.
Necessary for healing wound/sores – teenagers with active lifestyles may be
more at risk of injury.
Antioxidant properties are beneficial to teenagers to help prevent
cancers/heart disease in the future.
Vitamin A
Vitamin A has antioxidant properties – important for teenagers to reduce the
risk of cancers/disease in the future.
It is required to keep the mucous membranes in the throat, digestive, and
bronchial and excretory systems moist and free from infection.
It is also needed for the maintenance and health of the skin – important for
people of this age to look good.
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Vitamin B complex
Vitamin B allows the chemical reaction to occur which releases energy from
carbohydrates – important for teenagers, especially those who are very active.
Teenagers must ensure adequate supplies to obtain energy from their food
otherwise they will be lethargic, which may be common behaviour at this age
anyway and lack of B vitamins could make it worse.
Folic acid
This is essential for the formation of red blood cells and the prevention of
megaloblastic anaemia – vital for teenagers who require increased iron at this
stage of development as it can act as a ‘back up’ if iron is lacking. It is also
required for the release of energy from food.
Required for normal growth in children, particularly important during the
teenage ‘growth spurt’.
Maintains muscle tone – important for active, sporty teenagers.
Vitamin B12
This is important for the production of red blood cells to help prevent
pernicious anaemia. Teenagers may be susceptible to anaemia due to muscle
development (boys) and menstruation (girls).
Vitamin D
This is required to promote the absorption of calcium and phosphorus to build
strong bones and teeth – vital for developing teenage bones and teeth. It
promotes quicker healing of fractures, which active teenagers may be more
prone to.
Vitamin E
This has antioxidant properties – it protects polyunsaturated fatty acids from
damage by free radicals, especially cell membranes in the body . This is
beneficial to teenagers to help prevent cancers/heart disease in the future.
Vitamin K
This assists in the production of coagulation factors in the blood to enable it
to clot properly after an accident – vital at all stages of life.
Adults
General points
 The nutritional requirements of an adult will vary greatly depending on
age, gender, lifestyle and occupation.
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 Body growth declines in adulthood.
 Adults require a good diet to maintain and repair the body and to keep it
healthy.
 Activity levels along with body size will determine energy and nutrient
requirements.
 Women will need less food than men but will need more iron because of
menstruation.
 For women, nutrient requirement will change during pregnancy and after
the birth of a baby.
Dietary guidelines
 Adults who are not very active need to pay careful attention to their energy
intake because if energy intake exceeds energy output then the res ult will
be weight gain. Meals and portion sizes should be varied according to
energy needs.
 In comparison to adolescents, energy requirements are lower for both men
and women, as are requirements for protein, calcium and phosphorous.
 Reducing the intake of saturated fats, while increasing the totals complex
carbohydrates (TCC) foods will provide sufficient energy for active adults.
Elderly
Factors affecting dietary intake in the elderly
Physical changes that may affect diet are as follows:
 Decline in the senses of taste and smell.
 Dentition and the state of the mouth play an important part in the food
intake. Deteriorating teeth can cause difficulty with chewing and may
result in the eating of a more restricted range of foods , eg avoiding foods
that need a lot of chewing such as raw carrots, apples and toast.
 Decreased salivary secretion.
 Medication may result in loss of taste and dry mouth.
 Reduced secretion of hydrochloric acid in the stomach affect s absorption
of calcium, iron and vitamin B12.
 Insensitivity to thirst. Dehydration is common in the elderly and it causes
confusion and constipation.
 Decline in renal function (kidney), affecting drug excretion and
maintenance of water balance.
 The effect of medication, often long term, on nutrient requireme nts and
appetite.
 Mental illness and depression are also likely to affect food intake. There
may be a complete disregard for eating, with a loss of sense of time so that
mealtimes are ignored.
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 Lack of mobility, eg people with arthritis, may cause difficul ty in
shopping, preparing and cooking food.
 Possible reduction in the efficiency of the immune system, making
infections more likely.
Social factors affecting diet are as follows:
 Availability of money – many retired people live on a fixed income. A
limited budget may influence food choice.
 Lack of education about the importance of nutrition.
 Social isolation may be the result of retirement, rehousing, death of friends
and relatives. Where an effort is made to share food and eat in company,
food intake is better.
 An elderly person living alone may lack the motivation to prepare a
balanced diet and may snack on prepared high -fat and high-sugar foods.
Dietary requirements
In general, as people get older their dietary needs approach those of the very
young, ie they need a diet that is nutrient dense, since energy requirements
fall but nutrient requirements do not. The elderly use the nutrients for general
functions but some may have more importance than others.
Energy
The elderly have a wide range of energy requirements. A fit, active retired
person may be more active than when they were at work, whilst others,
because of infirmity, may be chair - or bed-bound. Generally, as people grow
older, they need less energy as usually they are less active.
The gradual loss of lean body tissue with age reduces the basal metabolic
requirements.
More elderly people are overweight rather than underweight due to lack of
exercise.
Obesity can be a problem – increased risk of heart disease, high blood
pressure, extra weight puts undue strain on joints.
Non-starch polysaccharides
Constipation is common in the elderly. To alleviate this, an increased intake
of foods high in NSP is recommended. Sufficient liquid should be drunk and
exercise will also help prevent constipation. The elderly often may not have
sufficient fruit and vegetables in the diet due to cost or difficulty in
preparation.
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Protein
A reduced income may mean that it is not possible to buy much meat or other
protein foods. Elderly people may avoid protein f oods like meat because of
their cost and texture. Protein intake must be used for wound healing and
tissue repair rather than for energy needs.
Micronutrients
There is a lack of specific recommendations for the elderly for many of the
vitamins and minerals, although it is known that the ability to digest, absorb,
metabolise and excrete nutrients changes with age ( eg vitamin B12 absorption
is decreased because the intrinsic factor needed for its absorption is thought
to decrease with age).
Some elderly people, especially those living in institutions, may have low
intakes or low blood levels of a range of micronutrients.
Minerals
Iron
 The elderly should be encouraged to eat foods rich in iron to prevent
anaemia, eg meat, eggs, breakfast cereals, bread, b eans. They may be
susceptible to anaemia as the desire to cook declines.
 The elderly may have poor absorption of iron.
Calcium
 Eating several sources of calcium will keep bones healthy and prevent
osteoporosis, eg milk, cheese, bread, breakfast cereals.
 Calcium is also required for blood clotting, which could be important as
the elderly may be at more risk of falling.
 Calcium is an essential component of all bones so is required to help
prevent osteoporosis and will help with bone repair if the elderly pe rson
falls.
Sodium
 An excess of sodium is particularly dangerous in the elderly as it will
cause high blood pressure as a result of the expansion of extracellular fluid
volume.
Potassium
 A deficiency may result in muscular weakness and potassium is also linked
with a reduced risk of hypertension.
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Vitamins
Vitamin D
 If the elderly are housebound then they may lack exposure to sunlight and
be at risk from a deficiency of vitamin D. This will lead to poor absorption
of calcium and may cause osteomalacia.
 Vitamin D is the only vitamin where there is an increased recommendation
for the elderly as there may be an inadequate exposure to the sun in
summer.
 Kidney function declines with age and this results in less efficient
production of the active substance from vitamin D.
 People aged 65 years and over may have to take a vitamin D supplement as
well as regularly eating food sources (eg oily fish, cod liver oil and
margarine).
Vitamin A
 A good intake of this antioxidant vitamin is important as the elderly ar e
more at risk from cancers and coronary heart disease (CHD).
 Necessary for good night vision – the elderly often have failing eyesight.
 The elderly who have difficulty in chewing would benefit from fruit and
vegetables being pureed to meet dietary needs f or fruit and vegetables.
Vitamin C
 A good intake of this antioxidant vitamin is important as the elderly are
more at risk from cancers and CHD.
 Assists with the absorption of iron to prevent anaemia – the elderly
sometimes do not have a balanced diet and cannot be bothered to prepare
fruit and vegetables.
As well as attention to diet, elderly people should take part in some exercise,
which improves fitness, muscle strength and flexibility. This will help them
continue the everyday activities that are ess ential to independent living.
Vegetarians
Types of vegetarians
People follow a vegetarian diet for a variety of personal, philosophical,
ecological and economical reasons. Variations in strictness of vegetarianism
are largely dependent on the person’s beliefs and reasons for adopting
vegetarianism. This may be for a variety of personal, philosophical,
ecological and economical reasons.
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Lacto-ovo vegetarian
Lacto-ovo vegetarians do not eat meat, meat products or fish. They will eat
animal products such as eggs, milk, cheese and dairy products.
Lacto vegetarian
Exclusion of all meat, fish and poultry and eggs. Milk and milk products are
still consumed.
Vegan
Exclusion of all foods of animal origin. Diet comprises grains, vegetables,
vegetable oils, cereals, pulses such as beans and lentils, nuts, fruit and seeds.
Non-food animal products, such as leather, may also be avoided.
‘Semi’ or ‘demi’ vegetatarian
Exclusion of red meat or all meat, but fish and other animal products are still
consumed; some people also include poultry.
Pesco vegetarian
Exclusion of all red meat and poultry, but fish and other animal products are
still consumed.
Fruitarian
Exclusion of all foods of animal origin as well as pulses and cereals. Diets
mainly comprise raw and dried fruits, nuts, honey and olive oil. People
following this type of eating pattern are at great risk of nutritional deficiency;
their diets require vitamin and mineral supplementation.
Macrobiotic
The diet progresses through a series of levels, gradually eliminating all
animal produce, fruit and vegetables and, at the highest level, leading to a
restricted diet of cereal (brown rice) only. Fluids may also be severely
restricted. Children are particularly at risk of nutritional deficiency and
studies have shown that growth patterns are disrupted by the most restricted
macrobiotic diets.
Nutrition for vegetarians
Provided a vegetarian diet is well balanced, it should provide all of the
nutrients needed by the body throughout life.
Protein
Protein from animal-derived food contains all of the amino acids (protein
building-blocks) that the body needs, and so a vegetaria n diet that includes
animal products is likely to contain enough high -quality protein.
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Most plant food proteins (with the exception of soya) have a low content of
one or more of the amino acids needed by the body (essential amino acids).
Furthermore, different ones are missing in different plant foods, therefore
plant foods can be combined to provide high -quality protein. Complementary
combinations include:
 pulses/rice – bean casserole and rice, dhal and rice
 pulses/cereal – baked beans on toast
 nuts/cereal – peanut butter sandwich, nut roast.
If the proteins from different plant sources are eaten together (or at least over
a day), the amino acid profiles of the plant proteins will complement each
other. Deficits in amino acids in any one plant protei n will be compensated
for by the amino acids in another. Thus, if vegetarians and vegans eat a
variety of vegetable proteins there is no reason why their intake of protein
cannot be as good as that of a person who eats meat or other foods that
contain animal protein.
Carbohydrates
Vegetarians need to use complex carbohydrate as a source of energy. The
high intake of NSP in vegetarians will have a positive effect on health, as
more pulses, nuts, fruits and vegetables are consumed.
Fats
Lacto-ovo vegetarians should limit their consumption of dairy foods such as
cheese, butter, whole milk to avoid a large intake of saturated fats. Reduced fat versions of these foods should be used.
With vegans, the saturated fat content of the diet will be lower as more
polyunsaturated fats are consumed.
Minerals
Calcium
Vegetarians who consume milk and milk products are likely to have adequate
intakes of calcium.
Vegans can obtain adequate calcium from plant foods. Good sources include
tofu, green leafy vegetables, watercress, dried fruit, seeds and nuts. White
bread is fortified with calcium, as are soya milks. The presence of phytic acid
in wholegrain cereals and NSP may make calcium unavailable to the body.
Where requirements for calcium are high, supplements containing calcium
and calcium-fortified foods (such as fortified soya products) may be useful.
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Iodine
Lacto-ovo vegetarian diets usually contain adequate amounts of iodine, but
vegans are at risk of low intake. On the other hand, those who consume a lot
of seaweed may have excessive intakes of iodine. Consumption of small
amounts of iodised salt or seaweed is therefore advisable for those following
a vegan diet to ensure sufficient intake.
Iron
Much of the easily-absorbed iron (haem iron) in non-vegetarian diets comes
from red meat and offal.
Plant foods contain no haem iron at all. Iron from non -haem sources such as
eggs, cereal products, green vegetables, nuts and pulses is less well absorbed,
but the presence of vitamin C from fruit, fruit juices and vegetables will
enhance the absorption of non-haem iron, for example having beans on toast
and a glass of orange juice at the same meal. However, tea (because of
tannins) and the plant substances phytate and NSP may reduce iron
absorption. Iron may be unavailable to the body from certain plant foods due
to the presence of phytic acid.
Provided sufficient iron is included in the diet, iron deficiency anaemia is not
common amongst vegetarians and vegans, but iron deficiency anaemia has
been reported in macrobiotic vegetarians who followed a very restrictive diet
and consume brown rice, which is rich in phytates, as their staple food.
Zinc
Foods considered to be the best sources of this mine ral include meat, poultry,
dairy products, bread and other cereal products, and seafood. If many of these
foods are excluded, dietary intake may be low but it is thought that adaptation
to the diet might occur with time, resulting in an increase in the pro portion of
zinc absorbed from the intestine.
Good plant sources of zinc include bread and cereal products, pulses, nuts
and seeds, but many of these are also high in phytate, which inhibits the rate
of zinc absorption. Although unrefined foods (eg wholem eal bread and brown
rice) do contain more phytate, they are still preferable to refined sources,
which contain less zinc and other micronutrients.
Vitamins
Most vitamins can be provided by foods of plant origin. However, vitamin
B12 is found only in foods of animal origin, and there are few plant sources
of vitamin D.
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Vitamin B12
Although the body’s requirement for vitamin B12 is only a few micrograms
per day, it is essential that vegans, and other people who avoid all animal
foods, include a source of vitamin B12 in their diet, either as a supplement
(usually in tablet form) or as fortified foods (such as yeast extract, fortified
soya milk or fortified breakfast cereal).
Vegans may be at risk of developing megaloblastic anaemia.
Vitamin D
Low vitamin D intake has been found among the Asian population,
particularly among children, adolescents women and the elderly, many of
whom are vegetarian. Prolonged deficiency of vitamin D results in rickets in
children and osteomalacia in adults. A combination of factors may be
associated with low vitamin D status, including:
 low exposure to sunlight – this may be due to seclusion or strict dress
codes limiting vitamin D synthesis in the skin
 type of vegetarian diet – vitamin D is found naturally in only a few foods,
all of which are of animal origin, for example meat, oily fish such as
mackerel and sardines, eggs, whole milk and its products
Fortified foods can help to contribute to the amount of Vitamin D in the diet
Some breakfast cereals, soya milk, yoghurts and all margarines (required by
law in the UK to contain vitamin D) and reduced -fat spreads are fortified with
vitamin D.
Weight-reduction diets
Many people in the UK are overweight as although the average energy intakes
of the population have decreased over the past few years, activity levels have
also dropped. People are taking less exercise and there are now more laboursaving devices and these factors may contribute to the increase in the number
of people who are overweight or obese.
Why do people put on weight?
If we eat food that provides more energy than we need for our normal
activities and lifestyle, this extra energy is stored as body fat. For body
weight to remain constant, energy intake must equal energy output.
Dietary guidelines
The most effective and healthy way to reduce weight is to take in slightly less
energy from food than the body needs each day. The body t hen makes up the
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difference by releasing energy it has stored as fat. Gradually the stores of fat
are reduced. Usually a diet promoting 1000 –1500 kcals per day is
recommended, depending on the individual. In particular, those trying to
reduce weight should:
 cut down on total intake of food eaten each day
 cut down on sugary and fatty foods.
 eat more total complex carbohydrate, NSP -rich foods and fruit and
vegetables, which are low in calories and are good sources of NSP,
vitamins and minerals – these foods are filling and will help prevent
snacking on sugary, fatty foods
 use cooking methods that do not involve adding fat.
Very low calorie diets, ‘crash’ diets and meal replacement drinks are
advertised as a quick and easy way to lose weight. These types o f diet can
cause problems because:
1.
2.
3.
4.
5.
they do not encourage the dieter to change their eating habits in the
long term
once normal eating resumes, weight may be put back on quickly
they often lead to loss of muscle instead of fat
they may not be nutritionally balanced
they can be expensive.
Refer to notes on Health and dietary diseases: obesity
Sports performance
Good nutrition will not guarantee athletic success but without it, an athlete’s
full potential will not be realised. The increased need for spec ific nutrients
depends not only on the amount of exercise undertaken but also the type,
intensity and duration of the physical activity.
Carbohydrates
High levels of physical activity, for example in intensive training for
competitions, will require an increase in energy intake. Carbohydrate is the
most important fuel for an active person and is stored in the muscles as
glycogen. This store of glycogen needs to be topped up each day.
Many sports include very high exercise intensity, which may be of shor t
duration such as sprinting, or expend energy over a longer time in endurance
sports such as cycling races. During endurance sports the body uses energy
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from its own energy stores – fat from adipose tissue and carbohydrates stored
as glycogen in the liver and muscles.
The energy used will have to be replaced by a nutritionally balanced diet that
meets the extra energy needs. Care must be taken to ensure that the diet does
not become unbalanced if athletes consume too many high -energy snacks that
are too high in fat and too low in carbohydrate and micronutrients.
A low-fat, high-carbohydrate snack or light meal should be eaten about 2 to 3
hours before exercise – this allows time for the stomach to empty before the
sports event. Athletes should then start refuelling energy stores after exercise
with low-fat, high-carbohydrate food. After strenuous exercise,
approximately 1 g of carbohydrate per kilogram of body weight should be
consumed. If the exercise was light then 50 g of carbohydrate should be
enough.
An insufficient supply of carbohydrates to muscles can lead to fatigue during
prolonged physical activity. Consumption of glucose or other carbohydrates
before or during exercise has been shown to postpone fatigue, conserve
muscle glycogen and improve performance. A sufficient supply of the B
complex vitamins should be eaten in order to ensure the release of energy
from food.
The type of carbohydrates that should be consumed include plenty of starch rich foods such as bread, pasta, rice and cereals. H igh-fibre varieties should
be chosen.
Sweet, sugary foods should only be consumed in small amounts. They can be
useful sources of carbohydrates if energy requirements are high.
Fluid
Fluid needs also need to be increased in response to training, with ad ditional
fluid losses from sweating being influenced by the intensity and duration of
exercise and climatic conditions.
Large sweat losses may cause severe dehydration, impaired blood circulation
and heat transfer, leading to heat exhaustion and collapse . As well as looking
after total fluid requirements over the day, the athlete should also drink
before, during and after each workout.
Water is an excellent sports drink but if the exercise is strenuous or if it lasts
longer than an hour then dilute fruit juices or a suitable sports drink should be
consumed as these will supply some carbohydrate as well as fluid.
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Protein
Strength and endurance athletes do have a higher requirement than the
average person for protein. However, this requirement can usually be met by
having a healthy balanced diet so no additional sources of protein require to
be eaten.
Protein is needed to support muscle gain and repair damaged body tissues. If
insufficient carbohydrate is eaten to fuel muscles, then protein will be used
instead.
Studies have shown that the large protein supplements taken by many athletes
are not effective in either increasing muscle mass or boosting performance.
Vitamins and minerals
There is no convincing evidence as yet that any particular vitamin o r mineral
supplements boost performance in athletes who eat a nutritionally balanced
diet. There may be small increases in requirements for some water -soluble
vitamins, such as vitamin C, thiamine, niacin and riboflavin, in those athletes
who take part in very vigorous activities. However, a well-balanced diet
should provide these.
Vitamin and mineral supplements may be required by athletes who restrict
their energy intake, use severe weight loss practices or eat a high carbohydrate diet with a low micronutrient content.
Some athletes are at risk of becoming iron deficient. Iron requirements may
need to be increased due to growth needs.
Anaemia in athletes is usually due to low dietary intake. This is more likely
in athletes, often female athletes, who restrict their energy intake to keep
their body weight low.
Exercise may increase iron losses and it may impair the increase in iron
absorption that normally happens when iron stores are low.
Inadequate iron intake can reduce exercise performance. Athlet es with low
iron stores often complain of tiredness and an inability to recover after heavy
training.
Many female athletes have such low body weight that they stop menstruating.
A serious outcome of menstrual disturbance is either the high risk of direct
loss of bone density or failure to gain peak bone mass that should occur
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usually 10–15 years after the onset of puberty. This may affect their bone
health and make them more prone to developing osteoporosis in later life.
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Resource management
Content
Elaboration
Nutrients and their effect on the health
and development of individuals
Protein
Fats – saturated, unsaturated, trans
fatty acids
Carbohydrates
Reference should also be made to sections on health of individuals,
micronutrients, antioxidants and dietary diseases
It is important for good health to eat a balanced diet. A balanced diet
provides all the necessary nutrients in the correct proportions and quantities
to meet our needs. One way to follow a balanced diet is to make sure we eat a
variety of foods that supply a range of nutrients.
Protein
Our bodies are composed of millions of cells that are constantly being
replaced and repaired. As the body grows, new cells are added. Each cell
contains a substance called protoplasm, which contains protein.
There are many different proteins and they are all complex molecules that
contain oxygen, carbon, hydrogen and nitrogen. Protein molecules are made
up of small units joined together like links in a chain. These units are called
amino acids.
At least 22 amino acids are known to occur naturally. Different proteins are
made when different numbers and types of amino acids combine. Of the 22
amino acids, some are called essential amino acids. These must be supplied
by the protein in the diet.
Sources
 Proteins are made up of amino acids.
High biological value proteins
 Proteins that contain all the essential amino acids are called high
biological value (HBV) proteins.
 These are found mainly in animal sources such as meat, cheese, fish, milk,
eggs.
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 The plant food soya beans contain HBV protein.
Low biological value proteins
 Proteins that lack one or more of the essential amino acids are called low
biological value (LBV) proteins.
 These are found mainly in plant foods such as:
– cereals, eg wheat, rice, oats
– pulses, eg peas, beans, lentils
– some nuts, quorn.
 LBV protein foods are not inferior to HBV protein foods. If a combination
of LBV foods are eaten together, eg beans on toast, then the essential
amino acids which are limited in one are provided by the other. In this
way, proteins complement each other to provide a sufficient supply of
essential amino acids.
Functions
Proteins are essential to life; all living cells are built and replaced by protein
molecules
The main purposes of protein are as follows:
 Growth and maintenance of cells.
The number of cells in the body increases during periods of growth so in
childhood and adolescence protein requirements increase.
Protein is also used to form enzymes and antibodies and some hormones.
These substances are produced within cells.
 Repair of cells. Protein in the tissues is constantly being broken down and
must be replaced by amino acids from the diet. This happens at all stages
of life.
The secondary purpose of protein is to provide energy.
Excess protein will provide the body with energy, once it has been used for
its main purpose of growth, repair and maintenance.
However, if there is dietary deficiency of energy, protein will be used first as
an energy source rather than for growth and repair. Add ing carbohydrate to
such a diet will ‘spare’ the protein for its main purpose.
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Protein requirements
Everyone needs some protein in their daily diet, even when they have stopped
growing, but at certain times there are increased needs .
Babies and children require a lot of protein as they are growing rapidly.
Adolescents require protein for their rapid growth spurt.
Pregnant women require a little more than usual to cater for the growing
baby. Lactating mothers require more than usual for milk production during
breast feeding.
Fats
 The term ‘fat’ includes both fats (solid at room temperature) and oils
(liquid at room temperature.
 Fat is present in food either as ‘visible’ or ‘invisible’ fat.
– Visible fat is easy to detect in food, eg fat on meat, butter, margarine,
lard, cooking oil.
– Invisible fat is a constituent part of food and is difficult to detect, eg
pastry, cakes, biscuits.
Functions of fats
 They provide a concentrated source of energy.
 Polyunsaturated fats contains the essential fatty acids (EFAs), linoleic acid





(n-6, omega-6) and alpha-linolenic acid (n-3, omega-3). These and the
fatty acids synthesised from them are important in the formation of cell
membranes, particularly in nerve tissue. At least 1.2% of energy intake
should come from EFAs.
They provide a source of the fat-soluble vitamins A, D, E and K.
They surround and protect certain vital organs such as the kidneys.
They form an insulating layer underneath the skin and so help maintain
body temperature.
Foods containing fat provide a feeling of fullness (satiety) through
consumption.
Fats are required for the structure of all body cells.
Fats can be classified into:
 saturated fats
 unsaturated fats.
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1.
Saturated fats
Important points
Sources
 Fats which are solid at room temperature are
Mainly of animal origin:
 meat and its products, eg
pies, sausages, lard, suet
 fats, eg butter, hard
margarine, some blended
cooking oils
 milk and dairy products, eg
butter, whole milk, cheese,
cream, eggs
but also:
 coconut oil and palm oil,
which are used to make
biscuits, pastry, cakes
mostly made of saturated fatty acids
 A diet high in saturated fats tends to raise
blood cholesterol levels (particularly the low
density lipoprotein (LDL) the ‘bad’
cholesterol) in some people, increasing the
risk of heart disease
 The LDL tends to stick to artery walls,
increasing the risk of blood clots and blockage
of the artery
 Certain cancers, such as bowel and breast
cancer, have been linked with high intakes of
saturated fats
2.
Unsaturated fats
Important points
Sources
A. Monounsaturated fats
 Monounsaturated fats remain liquid at room
temperature, but start to solidify when chilled.
 Monounsaturated fats reduce the bad LDL
cholesterol but also maintain or slightly
increase the good high density lipoprotein
(HDL) cholesterol
 HDL cholesterol helps to ferry the cholesterol
away from the arteries to the liver, where it is
broken down into bile
B. Polyunsaturated fats
 Polyunsaturated fats usually remain liquid at
both room temperature and cold temperatures
 Polyunsaturates help to bring down blood
cholesterol levels
 There are specific polyunsaturates that are
vital for health and cannot be made in the
body. These are called essential fatty acids
(EFAs) and must be obtained from food




Olive oil
Rape seed oil
Avocados
Nuts
 Oily fish, eg mackerel and
sardines
 Pure vegetable oils, eg
sunflower, soya
 Nuts and seeds
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Essential fatty acids
The two main EFAs are:
(i) omega-3 (alpha-linolenic acid)
Omega-3 reduces the tendency of blood to clot
so reducing the risk of a heart attack.
It may also reduce the incidence of
inflammatory diseases such as rheumatoid
arthritis.
(ii) omega-6 (linoleic acid)
These tend to decrease bad cholesterol but too
much may also decrease good cholesterol.
Omega-3
 Oily fish – mackerel,
pilchards, sardines, herrings,
trout
Omega-6
 Polyunsaturated margarine
 Corn, sunflower and soya
bean oils
Both omega-3 and omega-6 are needed for
brain development in babies. Humans make
special linolenic and linoleic acids in breast
milk. This is one of the reasons why human
breast milk is best for babies.
 Another type of polyunsaturated fat is called
trans fatty acids
These fats are polyunsaturated fats artificially
hardened by adding extra hydrogen
They cause an increased risk of heart disease
and rheumatoid arthritis
Trans fatty acids increase blood levels of bad
cholesterol and may reduce levels of good
cholesterol
 Hard margarine
 Biscuits and cakes
 Commercially fried foods, eg
French fries from fast-food
chains
 Packaged snacks
 Any food label that indicates
hydrogenated or partially
hydrogenated fats/oils
Trans fatty acids are not listed on food
ingredients but hydrogenated or partially
hydrogenated oils are listed
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Carbohydrates
Functions of carbohydrates




Supply energy for all activities.
Supply energy to maintain normal body temperature.
Supply indigestible fibrous material (NSP) to aid digestion.
Are important in the structure of cells.
Carbohydrates can be subdivided into three main groups:
1.
2.
3.
monosaccharides (sugars)
disaccharides (sugars)
polysaccharides (starches).
Important points
Sources
1. Monosaccharides
Monosaccharides or simple sugars are singleunit carbohydrates.
There are three main monosaccharides:
 glucose
Fruit, vegetables, eg onions,
beetroot, available in powder,
liquid or tablet form, honey.

fructose (often called ‘fruit sugar’)
Fruit and vegetables, honey

galactose
Milk
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Important points
Sources
2. Disaccharides
These are double sugars made up of two
monosaccharides joined together.
There are three main disaccharides:
 sucrose
Used in cookery and obtained by refining
sugar cane or beet
Sucrose is formed from one unit of
glucose and one unit of fructose
 lactose
Found in the milk of mammals to supply
the infant with a source of energy; it is not
as sweet as sucrose
Lactose is formed from one unit of
glucose and one unit of gelactose
 maltose
Sometimes called ‘malt sugar’ and found
in cereals, where it is formed during
germination
Maltose is formed from two units of
glucose
Refined sugar cane or beet, some
fruit and vegetables
Milk
Germinating cereals, eg barley
3. Polysaccharides
These are called starches or complex
carbohydrates.
They consist of chains of monosaccharides.
The main polysaccharides are:
 starch
Formed from many glucose units joined
together like links in a chain
 non-starch polysaccharides
32
Bread, flour, potatoes, cakes
Wholegrain cereals – oats, wheat,
rice, wholemeal bread; skins of
fruit and vegetables
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Sugars
Sugars can be classified as:
 intrinsic sugars – those that form part of the cell structure of plants , for
example fruit
 extrinsic sugars – not part of the cell structure of plants. They include non -
milk extrinsic (NME) sugars, for example refined sugar, sugar added to
foods, extracted sugars in honey and fruit juice.
Starches
It is recommended that we should get most of our energy from starch or
complex carbohydrate foods rather than sugar. There are a number of reasons
for this.
 Starch foods are good sources of other nutrients . Examples could be
potatoes, which are also a source of vitamin C; bread is also a source of
protein, calcium and iron. Sugar is often described as ‘empty calories’
since it provides energy but no other nutrients.
 Starch foods provide bulk with few calories. Most of these foods provide
substantial amounts of water and NSP. This means that they are filling
without being a concentrated source of energy.
 Starch foods do not encourage tooth decay, as bacteria in the mouth do
not like starches. Sugar provides food for a cid-producing bacteria on the
surface of the teeth and this acid damages teeth.
 Starch foods are generally inexpensive foods. For example, bread and
breakfast cereals are inexpensive and are fortified with vitamins and
minerals.
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Resource management
Content
Elaboration
Nutrients and their effect on the health
Micronutrients
and development of individuals
Reference should also be made to sections on health of individuals, main
nutrients, antioxidants and dietary diseases
Micronutrients
Micronutrients are vitamins, minerals and trace elements found in the food
we eat. Vitamins are organic substances that are needed by the body in very
small quantities. They cannot be synthesised in sufficient amounts in the
body and therefore must be augmented by t he diet. They are usually part of
the enzyme system and are often involved in the metabolism of the major
nutrients of fat, carbohydrates and protein. The most common vitamins
required by the body are:






vitamin
vitamin
vitamin
vitamin
vitamin
vitamin
A
B complex
C
D
E
K.
Minerals elements found in our food are not always available to the body and
therefore their bioavailability is often limited. The mineral elements required
in the diet are:






calcium
phosphorus
sodium
potassium
magnesium
iron.
Trace elements are required by the body in smaller quantities than mineral
elements. The most commonly considered trace elements are:
 iodine
 copper
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 selenium
 zinc
 fluorine.
Bioavailability is described as the proportion of the nutrient from the diet
which is used in the body. Differing nutrients have differing bioavailabilities,
eg calcium, iron, zinc and copper have limited bioavailability. The
differences occur for varying reasons, for example:
 the presence of phytate, oxalate and other substances in food may bin d the
mineral elements, hence making them unavailable
 physiological factors, eg age, state of health and nutritional status, can
alter the bioavailability of some nutrients.
A varied diet is therefore essential to ensure an adequate intake of all the
required nutrients for each individual’s needs.
Micronutrients – minerals
1.
Calcium
Calcium is the most abundant mineral in the human body. Of the body ’s total
calcium, about 99% is in the bones and teeth , where it plays a structural role.
The remaining 1% is present in body tissues and fluids, where it is essential
for cell metabolism, muscle contraction and nerve impulse transmission.
Functions
 With phosphorus, it combines to make calcium phosphate, which is the
chief material that gives hardness and strength to bones and teeth. The
skeleton is made up of many bones joined together to make a rigid
framework to keep us upright, to enable us to move and to make a
protective casing for the delicate parts of the body. The teeth need to be
built strongly too, so that we can chew and eat a variety of tougher hard
food.

Before birth, the bones and teeth begin their formation as an elastic
substance known as cartilage. In a child, the cartilage that is to become
bone becomes harder and more rigid as the minerals calcium and
phosphorus becomes enmeshed in the cartilage. This process is called
calcification.

Ninety-nine per cent of the calcium in the body is in the bones and teeth.
One per cent is in plasma and soft tissue. Over 90% of bone tissue is laid
down during the childhood years of growth. Bone mass reaches a peak at
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about the age of 30 to 35 years and there after declines progressively. In
women at about the time of the menopause, the rate of bone loss increases
markedly. There is little evidence that increasing dietary calcium at any
age helps to reduce bone loss.

Calcium is required for maintenance of bones and teeth once formed.

Calcium is also needed for correct functioning of the muscles and the
nerves. Without calcium, the muscles cannot continue t o contract and
impulses cannot be transmitted efficiently along the nerves.

Calcium is required for part of the complex mechanism that causes blood
to clot after an injury.

Calcium is required for the normal action of some hormones.
Sources
Milk, milk products, cheese, bread (added to white flour by law), bones of
canned fish, hard water.
Absorption of calcium
Although on chemical analysis a food may appear to be very rich in calcium,
we cannot always make use of the calcium it contains.
Green leafy vegetables often contain fairly large quantities of calcium, but
they have also a great deal of fibre. Fibre cannot be digested in the human
digestive system, and as the fibre and the calcium may be closely linked,
much of the calcium may be made unavailable to the body. For this reason,
we can absorb the calcium in milk much better than the calcium in cabbage.
Lactose present in milk also increases the absorption of calcium.
A substance called phytic acid is found in wholegrain cereal foods such as
wholemeal bread and in oatmeal, peas, beans and nuts. Phytic acid combines
with calcium in a form that prevents us absorbing the calcium from th is food
following digestion.
To overcome any possible shortage of calcium that might result from this
association with phytic acid, it was recommended by the Medical Research
Council that white flour be enriched with calcium. White flour itself is
practically free from phytic acid (unlike wholemeal flour) but it was thought
wise to enrich some of our staple foods that would be eaten every day by the
vast majority of the population.
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The amount of calcium and phosphorus that can be extracted from the
digested foods is absorbed through the wall of the small intestine into the
blood to be carried to the bone – and tooth – building areas of the body.
Factors affecting the absorption of calcium
1.
Factors assisting absorption
Vitamin D
 Vitamin D controls absorption of calcium so there must be a good supply
in the diet.
 Without vitamin D we cannot make use of the calcium in food.
Lactose
 This is a sugar present in milk and increases calcium absorption on
hydrolysis.
Protein
 The amino acids formed from protein as a result of digestion combine with
calcium to form soluble salts and these salts are very readily absorbed.
2.
Factors limiting absorption
Lack of vitamin D
 Without vitamin D less calcium will be absorbed and this deficit may
adversely affect the strength of bones and teeth.
Phytic acid
 Phytic acid is found in wholegrain cereal foods and combines with calcium
in a form that prevents calcium being absorbed.
NSP
 NSP cannot be digested in the human digestive system as the NSP and
calcium bind together. Much of the calcium in fibrous foods is made
unavailable to the body.
Fats
 Fats, particularly saturated fatty acids, form insoluble soaps with calcium
that cannot be absorbed.
Oxalic acid
 Oxalic acid, which is particularly high in rhubarb and spinach, also
interferes with calcium absorption.
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Control of calcification
The actual absorption of calcium and the minerali sation of bones and teeth
are controlled by vitamin D. Without this vitamin, we cannot make use of the
calcium in the food we eat. In the body the deposition of calcium phosphate is
also governed by a hormone produced by the small glands in the neck called
the parathyroid glands. The work of the parathyroid hormone is to regulate
the amount of calcium and phosphorus carried by the blood.
After absorption of the minerals into the bloodstream, the parathyroid
hormone causes calcium phosphate to be deposited in the bones and teeth
until blood is left with only its small normal quota of calcium and phosphorus
carried by the blood.
Calcium requirements
Determining calcium requirements is difficult for several reasons. Adaptation
to both high and low intakes occurs, but it occurs slowly. At dietary calcium
intakes of about 800 mg/day absorption is about 20%. If intakes are low as
250mg/day, about 70% is absorbed.
Our bodies do appear to adapt to low intakes of calcium by increasing the
amount the body absorbs from the food we eat. Many different studies have
shown that populations with very low calcium intakes, by our standards, have
normal amounts of calcium in their bones and tissues, and this evidence is
used to argue that we do not need to increase our calc ium intakes.
Effects on health and development
Humans have a constant need for calcium throughout their li ves. While
new bone is made, existing bone is taken away, so that in young children the
whole skeleton is replaced over 2 years. In adults, this takes between 7 and
10 years. Research shows that regular exercise stimulates new bone
production. The formation of bones and skull in the form of calcium
phosphate is needed at all stages of life.
(a)
Babies
 Calcium plays a part in the formation of the enzyme trypsin and the
activation of rennin, which is important in the digestion of milk – it
is necessary to digest milk and extract nutrients for well -being.
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(b)
Children
 Rapid period of growth – calcium is required for developing skeleton
and building bone mass for adulthood.
 If children suffer a shortage of calcium when they are growing,
bones and teeth cannot be properly mineralised. The skeleton is not
made strong enough to support the body, and the legs which carry its
main weight become badly formed. This condition is known as
rickets. The long bones of the legs bend under the weight of the
body; knock knees and bow legs are typical symptoms of rickets.
Rickets are no longer a major problem in this country, partly due to
the fortification of margarine and vitamin D with calcium. Because
bone formation is closely linked with vitamin D, rickets may also be
caused by a shortage of vitamins.
 Another sign of calcium deficiency in children is tooth decay and
loss of teeth.
 Some of the Asian population still have rickets as some traditional
Asian diets are low in vitamin D and Asian cultures do not encourage
exposure to sunlight – the best source of vitamin D.
(c)
Teenagers
 Teenagers who have a poor diet low in calcium and an inactive
lifestyle do not reach maximum bone density during the period of
growth in their teenage years. This can lead to osteoporosis in later
life.
 Calcium is required for blood clotting – teenagers with an active
lifestyle may be more prone to accidents.
(d)
Adults
 In adults a shortage of calcium from food results in calcium being
removed from the bones and teeth, but not being replaced. Gradually
the bones lose their strength and may finally become soft and weak ,
making them become deformed and painful. A shortage of calcium in
adults can lead in this way to the disease of osteomalacia (adult
rickets).
(e)
Pregnancy
 Necessary for the foetus – used for developing skeletal structure.
 During pregnancy, calcium absorption increases and no additional
calcium is generally needed. An exception may be a pregnant
teenager who needs dietary calcium both for herself and for the
foetus
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(f)
Elderly people
 Osteoporosis occurs in elderly people, particularly in women after
the menopause. Calcium is gradually lost from the bones , which
become more porous and fracture more easily. Peak bones mass
(PMB) when the bones are at their most dense, occurs between the
ages of 35 and 40 years. From this age, loss of bone occurs at the
rate of 3% of PMB per year. In women during the 5 years following
the menopause the loss is greater due to the deficiency of the
hormone oestrogen. Hormone replacement therapy has been shown to
reduce this loss. Osteoporosis is not thought to be caused by a lack
of calcium or vitamin D, but plenty of dietary calcium together with
regular exercise are recommended as preventative measure.
 Poor bone density leads to osteomalacia/osteoporosis.

Bone loss can be affected by wide variety of factors, for example:
 immobility
 early menopause as there is an increased risk of osteoporos is
 family history (genetics)
 low calcium intake
 underweight
 high alcohol intake
 smoking.
2.
Iron
Iron is a mineral found in every cell of the body. It is vital for good health
and for mental and physical well-being.
Functions
 Iron is a component of haemoglobin, the substance which gives red blood
cells their colour. Haemoglobin is required to transport oxygen around the
body to every cell for the production of energy and the maintenance of all
cell functions. Haemoglobin is made of complex protein molec ules that
contain iron.
 One of the important functions of the blood is to serve as a transport
system, the blood carrying nutrients from where they are derived to where
they are needed. For example, digested foods from the intestine pass into
the blood for transport to all cells. Similarly, oxygen is absorbed into the
blood in the lungs and carried to all parts of the body in the bloodstream.
An adequate supply of oxygen is essential for the body cells to carry out
their functions. A shortage of oxygen can damage the cells; if they are
deprived of oxygen cells will die.
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 Making energy. Iron is essential in the chemical reactions that produce
energy from food. If your iron levels are low then your body may not be
able to use all the energy available to it.
 Ensuring a healthy immune system. The cells that fight infection and
defend the body against foreign organisms depend on adequate stores of
iron. If iron stores are low, the body is prone to more frequent infections.
Sources
Good sources – liver, kidney, corned beef, cocoa, plain chocolate, red meat.
Reasonable sources – white bread (added by law), curry powder, treacle,
dried fruit, pulses such as beans and lentils, fortified breakfast cereals.
Wholemeal grains – these contain iron, but it may be una vailable to the body
due to the presence of phytic acid.
Green leafy vegetables, eg broccoli and spinach – these contain some iron,
but it may be unavailable to the body due to the fibre content.
Absorption of iron
It has been estimated that only 5–20% of the iron in the diet is normally
absorbed.
To prevent an excess of iron entering the body from food normally eaten, the
intestine has a safeguard that allows only the absorption of the quantity of
iron needed at that time. This safeguard is called the mucosal block.
Requirements within the body may vary from day to day , but iron must
always be included in the diet.
The amount of iron that is absorbed appears to be influenced by the need of
the body for iron. Someone who is deficient in iron will be abl e to absorb
more than a person who has adequate stores of iron.
Absorption is also affected by the type of iron. Iron obtained from meat is
more easily absorbed than iron from plant foods. The iron in meat is found in
the form of haem iron, which is easily absorbed.
Iron in cereals and vegetables is non-haem iron, which is less easily
absorbed. This iron is present as ferric iron but is more easily absorbed in the
form of ferrous iron. Vitamin C helps in the conversion of iron from its ferric
state to the easily absorbed ferrous state and helps absorption of the ferrous
iron from the intestine. Vitamin C significantly increases iron absorption ,
especially from plant food.
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Too much fibre in leafy vegetables and fresh fruit, or phytic acid in
wholegrain cereal foods prevents the absorption of iron from foods which,
purely by chemical analysis, may appear to be sources of the mineral. Large
carbohydrate molecules may also surround the iron molecules and so prevent
their uptake by the mucosal cells. A poor di et that is rich in low
carbohydrates but low in protein is likely to be low in iron content, and the
actual composition of this kind of diet slows down the absorption of what
iron there is.
Tannin, found in tea and coffee, is also thought to make iron more difficult to
absorb.
Effects on health and development
General symptoms of low iron intake for all ages
If for any reason the body is short of iron, for example if the daily food does
not contain enough or if it is unable to be properly absorbed from the
intestine, red blood cells are made with less than their full quota of
haemoglobin. This is the cause of the condition known as iron -deficiency
anaemia.
Because there is less haemoglobin in the cells, less oxygen can be carried by
the blood, and because they are short of oxygen the body calls work less
efficiently. The muscles become more easily fatigued and the characteristics
signs of anaemia are tiredness, breathlessness and listlessness (lack of
energy). When the blood is anaemic the heart has to b eat more quickly to
carry the blood’s smaller load of oxygen to the muscles and this causes
palpitations during exercise.
Iron stores in the body become depleted and haemoglobin synthesis is
inhibited. Symptoms of anaemia include tiredness, lack of stamin a,
breathlessness, headaches, insomnia, loss of appetite and pallor. All these
symptoms are associated with decreased oxygen supply to tissues and organs.
Iron also plays an important role in the immune system: people with low iron
levels have lowered resistance to infection.
Research has also shown iron deficiency to be associated with impaired brain
function, and iron deficiency in infants can result in impaired learning ability
and behavioural problems.
(a)
Babies and children
 Foetus builds store of iron in its liver from the mother’s blood for
use during its early stages of life.
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 Babies are born with enough iron to last 4 months, as milk contains
no iron. After this, they require iron from food. During body growth,
when the actual volume of blood is increasing and therefore the
number of red blood cells also needs to be increased, good supplies
of iron are necessary. As new blood is being produced, new red
blood cells continue to replace existing but worn cells. Children
therefore need iron for both building and repair of the blood.
(b)
Teenagers
 Teenagers require iron during their rapid growth spurt to cope with
the increased volume of blood.
 Teenage girls may require more iron due to the blood losses during
menstruation.
 An increasing number of teenagers are following vegetarian diets,
cutting out meat as a source of iron. Snacking or grazing during the
day could also potentially reduce iron intake.
 Teenagers may be more susceptible to anaemia if diet is poor .
(c)
Pregnancy
 The increased needs of pregnancy should be met without a further
increase in iron intake because of cessation of menstrual losses and
the mobilisation of some of the mother’s stores. Dietary
supplementation may be needed by mothers with low iron stores or
teenage mothers. After the birth of the baby, iron supplies must be
replaced.
(d)
Adults
 Adults need iron only for the normal replacement of old cells with
new ones, although children and adults alike need extra iron to
replace any blood that may be lost through
bleeding/accidents/operations.
 Women with a high menstrual loss may require increased iron to
prevent anaemia.
 Individuals with a high intake of dietary inhibitors , eg tannin in tea,
may need more iron.
(e)
Elderly people
 Some elderly people may have poor absorpti on of iron and so may
become anaemic.
 The elderly often do not get an adequate diet and this can cause a
shortage of iron, resulting in feeling tired and listless.
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3.
Phosphorus
Functions
 Phosphorus works in conjunction with calcium and therefore has th e same
functions. It combines with calcium to make calcium phosphate, which is
the chief material that gives hardness and strength to bones to teeth.
 It is also present in all living cells, where it is involved in the release of
energy in the body.
Sources
Phosphorus is present as phosphate in all plant and animal cells, and is
therefore present in all natural foods. It forms part of many proteins, and is
often used as an additive in manufactured foods.
Phosphorus is found in so many of the foods we eat that we are unlikely to be
short of phosphorus provided we eat a fairly varied diet. Of all foods, cheese,
meat, eggs and flour and bread (except wholemeal) supply the majority of our
phosphorus intake.
Effects on health and development
 There appears no known deficiency, due to sufficient phosphorus being






readily available in the diet.
Plays an essential part in the basic biomechanical mechanism by which
energy is obtained for the processes of life – necessary for all age groups.
Required in conjunction with calcium for bone formation. Essential that
adequate supplies are available at times of bone growth , eg young
children/teenagers.
The elderly must also have adequate supply to ensure strong bones to
offset osteoporosis/osteomalacia.
Speeds up the healing process and puts a stop to calcium-loss from injury.
Keeps muscles, including the heart, contracting regularly and smoothly.
Assures transmission of impulses from one nerve to another.
Those at risk for low phosphorus
 Those on weight-loss diets of 1000 calories a day or less.
 Pregnant and nursing women.
 Those who drink heavily.
4.
Sodium
Sodium is a vital component of the fluid bathing all cells. It is closely
involved with control of body fluid content. It has long been known that the
amount of dietary sodium needed to perform its vital function is only a
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fraction of the amount most people in the UK take. The mature, healthy
kidney is capable of regulating body sodium very accurately.
Functions
 Body fluids – all body fluids contain salt but especially those fluids
outside the cells such as blood. Sodium allows nutrients to flow into body
cells and waste products to flow out.
 Water balance – maintaining the water balance in the body. Salt intake
may have to be severely restricted in certain kid ney diseases or where
water is retained in the body.
 Blood pressure – continual high sodium intakes can be associated with
high blood pressure
 Muscle activity – during strenuous work or exercise, large amounts of salt
may be lost through sweating. This will cause a lowering of the salt
concentration of the tissue fluids, resulting in weariness and muscular
cramps.
 Essential for the transmission of nerve and muscle impulses.
Sources
Sodium is usually eaten as common salt, added as salt to food , eg cheese,
bacon, fish, processed foods and found naturally in fish, meat and in many
other foods. On food labels both sodium and the salt equivalent are usually
stated (salt = 2.5 times the sodium).
Effects on health and development
(a)
Babies

(b)
Children/teenagers

(c)
Too much salty foods for babies may result in kidney damage.
A taste for salty foods should not be encouraged in childhood as it
may carry on into adulthood and result in hypertension.
Adults

Evidence suggests that sodium plays a part in the development of
high blood pressure (hypertension). It seems that some people’s
kidneys may have problems getting rid of sodium. This causes fluid
to be retained in the body to dilute the blood. Over a period of time
the retained fluids also make the blood vessels contract. The
increased amount of blood the heart has to pump through the blood
vessels, and the resistance to flow, make the heart work harder.
This may cause the blood pressure to rise.
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


Some people are more likely to develop high blood pressure than
others if their sodium intake is high.
It is sometimes necessary to place a person on a salt -restricted diet
for certain medical conditions, eg heart, kidney or liver disease,
high blood pressure.
There is a relationship between sodium intake and a r ise in blood
pressure with age.
Possible ways of reducing sodium intake
 Reducing the amount of salt used when cooking, eg steaming foods with





5.
no added salt.
Using herbs and spices to season foods.
Tasting food before adding any salt.
Eating more home-prepared meals where you are in control of the amount
of salt used.
Choosing processed foods that have been manufactured with a reduced
amount of salt.
Eating yeast-raised cakes, eg doughnuts and Chelsea buns instead of cakes
raised with baking powder, which contains sodium compounds.
Potassium
Potassium is an essential mineral needed to regulate water balance, levels of
acidity, blood pressure and neuromuscular function. This mineral also plays a
critical role in the transmission of electrical impulses in the heart.
Potassium and sodium work together in the body to maintain muscle tone,
blood pressure, water balance and other functions. Many researchers believe
that part of the blood-pressure problem caused by too much salt (which
contains sodium) is made worse by too little dietary potassium.
Function
 Potassium is found inside body cells. It is involve d in the regulation of
the fluid content of cells and the function of muscles and nerves.

Deficiency is rare, but may occur if potassium is not absorbed, eg as a
result of excessive use of laxatives or vomiting. Symptoms of deficiency
include depression, mental confusion and muscular weakness. The effect
on the heart can lead to heart failure.

It is thought that a fairly high intake of potassium may counteract the
effects of a high sodium intake and reduce the likelihood of developing
high blood pressure.
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Sources
Found in a wide variety of food, particularly fruit (especially bananas) and
vegetables, meat and milk.
Effects on health and development
 Potassium regulates the balance of the body acids and plays a role in nerve




6.
and muscle function. Together with sodium, potassium works to regulate
blood pressure and water balance and to keep the heart muscle beating in a
steady, normal rhythm.
Potassium helps sharp, clear thinking by assuring adequate oxygen
transport to the brain.
Potassium levels are thought to be linked with sodium levels in the
prevention of hypertension – an important factor for the middle aged and
elderly.
Prolonged diarrhoea may lead to potassium depletion , which may result in
heart failure.
Very elderly people whose muscles waste away may become short of
potassium.
Magnesium
Research studies have shown that magnesium plays an even greater role in
health than was previously thought. Second only to potassium in terms of
concentration within the individual cells in the body, the fun ction of
magnesium revolves primarily around its ability to activate many enzymes ,
including those in DNA and protein synthesis.
Function
 Magnesium is found together with calcium and phosphorus in bones and
teeth. It is necessary for normal skeletal devel opment so important in
children and teenagers
 It is also needed in the body for the functioning of enzymes. Magnesium
participates in more than 300 enzymatic reactions in the body , including
those responsible for energy metabolism, fatty acid metabolism, p rotein
synthesis, neuromuscular contractions/relaxations, bone integrity and
prostaglandin synthesis, to name but a few.
 It has a significant role to play in the production of energy and in
maintaining and optimising muscle health. Having a good supply of
magnesium can facilitate oxygen and energy being delivered to working
muscle tissue.
 The muscles themselves actually contain about 26% of all magnesium
found in the body, with 50–60% in the bone and the rest in muscles and
other soft tissue. The magnesium in bone provides a reservoir in case
deficiencies occur in soft tissue magnesium. The tissues with the highest
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concentration of magnesium are those that are metabolically active, which
again links to magnesium's critical role in energy production.
Sources
Plant foods such as wholegrains, vegetables (such as spinach, potatoes) and
legumes (such as black beans), tofu and some types of seafood (such as
halibut, oysters, crab).
Deficiency of magnesium is rare but may occur as a result of:
 excessive loss during bouts of diarrhoea or vomiting
 unsuitable slimming habits
 chronically poor diet
 alcoholism – alcohol increases urinary excretion of magnesium but
alcoholics are also often malnourished
 malabsorption syndrome. We generally absorb about 50% of dietary
magnesium. Diets high in fibre, or high phosphorus or calcium levels
(usually in the form of supplements) can result in decreased absorption.
Symptoms include:
 loss of appetite, nausea and muscular weakness
 muscle cramps, irritability and confusion
 disturbed and quickened heart rhythm
 anxiety and insomnia.
Effects on health and development
 Magnesium is needed by all groups of people for the functions above.
 Magnesium is particularly important for children’s skeletal development.
Micronutrients – trace elements
1.
Iodine
Functions
 Iodine is required to make the hormone thyroxine, which is produced by
the thyroid gland in the neck.
Thyroxine, along with other hormones, is required for the following:
 Normal body growth and development of the central ner vous system.
 Helps to regulate body temperature.
 Energy production and oxygen consumption in cells, thereby maintaining
the body’s metabolic rate.
 If the thyroid hormone in insufficient, the basal metabolic rate is reduced ,
as is body activity. Normal growth and development are also impaired.
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Sources
Iodine is widely distributed in foods, but is found in good supply in:






seafoods
milk
egg
green vegetables, especially spinach
fresh water (depending on area)
iodised salt (added commercially).
Effect on health and development
A deficiency of iodine leads to a reduction in the amount of thyroxine
produced by the thyroid gland. As a result , the metabolism slows down and
the thyroid gland enlarges – called goitre. In foetal and infant development,
thyroid hormones, and therefore iodine, are essential for the normal
development of the brain. Insufficient levels can result in permanent brain
retardation of the foetus or newborn child.
In severe cases in children this can lead to cretinism which, in addition to
mental retardation, can cause stunted growth, and hearing and speech defects.
2.
Zinc
The mineral zinc is present in every part of the body and has a wide range of
functions. It helps with the healing of wounds and is a vital component of
many enzyme reactions. Zinc is vital for the healthy working of many of the
body’s systems. It is particularly important for healthy skin and is essential
for a healthy immune system and resistance to infection.
Functions
 Zinc has a range of functions. It plays a cruci al role in growth and cell
division, where it is required for protein and DNA synthesis, in insulin
activity, in the metabolism of the ovaries and testes, and in liver function.
 As a component of many enzymes, zinc is involved in the metabolism of
proteins, carbohydrates, lipids and energy.
 Zinc and copper are key components of superoxide dismutase, an enzyme
that speeds up antioxidant reactions and helps protect cells from free
radical damage.
 Zinc is vital for a quick-reacting immune system and is essential to the
proper development and maintenance of the immune system. Without zinc
the body could not fight off viruses, bacteria and fungi. A mild deficiency
of zinc may increase the risk of infection.
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 Zinc is a key component of the enzyme that activates vitamin A in the
retina. Zinc-deficient people may show signs of night blindness.
 In severe zinc deficiency, cells fail to replicate. This may be why zinc is
so important for the normal growth and development of children and the
sexual maturation of adolescents. Deficiency causes stunted growth and
delayed sexual maturing.
 There is some evidence that zinc is concerned with some of the processes
involved with foetal development.
 Zinc interacts with a number of hormones , including insulin.
 Some studies show that zinc plays a role in taste perception and appetite
regulation.
Sources
Zinc is present in a wide variety of foods, particularly protein foods. The
main sources are meat, milk, sardines, chicken, lentils, nuts, bread and other
cereals. A vegetarian diet often contains less zinc than a meat -based diet and
so it is important for vegetarians to eat plenty of foods that are rich in this
vital mineral. Good sources for vegetarians include dairy products, beans and
lentils, yeast, nuts, seeds and wholegrain cereals. Pumpkin seeds provide one
of the most concentrated vegetarian food sources of zinc.
Only 20% of the zinc present in the diet is actually absorbed by the body.
Dietary fibre and phytic acid, found in bran, wholegrain cereals, pulses and
nuts, inhibit zinc absorption. Phytic acid forms a highly insoluble complex
with zinc that the body cannot absorb. Cooking processes can reduce the
adverse effects of both phytic acid and dietary fibre on zinc absorption.
Effects on health and development
Zinc deficiency may exist in some groups, eg:




rapidly growing children
pregnant women
sufferers of anorexia nervosa
vegans.
Some other groups may also be at risk of a mild deficiency due to diet -related
problems, namely:
 pre-school children of low income families
 constant dieters
 the elderly who may make poor food choices.
Our body contains about 2–3 g of zinc. There are no specific storage sites
known for zinc and so a regular supply in the diet is required. Zinc is found
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in all parts of our body: 60% is found in muscle, 30% in bone and about 5%
in our skin. Particularly high concentrations are in the prostate gland and
semen. Men need more zinc than women because male semen contains 100
times more zinc than is found in the blood. The more sexually active a man is
the more zinc he will require. The recommended amounts of zinc for adult
men are a third higher than those for women.
The first signs of zinc deficiency are impairment of taste, a poor immune
response and skin problems. Other symptoms of zinc de ficiency can include
hair loss, diarrhoea, fatigue, delayed wound healing, and decreased growth
rate and mental development in infants. It is thought that zinc
supplementation can help skin conditions such as acne and eczema, prostate
problems, anorexia nervosa, alcoholics and those suffering from trauma or
post surgery. It is always better to seek the advice of an expert before using
supplements.
3.
Selenium
Selenium is an important mineral and antioxidant and has several functions in
the human body.
Functions
 It forms part of an enzyme system in the red blood cells.
 As an antioxidant, selenium is thought to be important in protecting
healthy cells against the damaging effects of metabolism, which may
contribute to cancer or other chronic conditions. Re search in this area is
ongoing.
 Selenium is best known as a component of glutathione peroxidases, a
family of antioxidant enzymes that reduce peroxides before they can attack
intracellular membranes. Selenium is an essential building block for these
antioxidant enzymes.
 Both selenium and vitamin E play a role in preventing lipid peroxidation
and membrane damage. Glutathione peroxidases promote the breakdown of
fatty acids that have undergone peroxidation, so eliminating highly
reactive free radicals. This reduction in free radicals spares vitamin E,
making it available to stop other chain reactions of free radicals. It could
therefore be said that selenium works in combination with vitamin E as an
antioxidant.
 Selenium interacts with iodine in thyroid hormo ne metabolism.
 It is also important in the immune system and for its response to infection.
 It is valuable to the health and development of all ages. Deficiency of this
trace element is unknown in the UK.
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Sources
Selenium is found in all foods in very low concentrations. Main sources
include fish, meats, eggs, shellfish, nuts and cereal products.
4.
Fluoride
Functions
 Fluoride may be an important factor in the strengthening of teeth against
decay by combining with calcium phosphate. It is thought that i t combines
with the protective enamel coating of the teeth, making them more
resistant to attack by the acid produced by bacteria in the mouth.
 It is involved in bone mineralisation.
Sources
Fluoride is found naturally in tea, sea fish, and in in water su pplies in some
parts of the country. Fluoride is also added to toothpaste.
Effects on health development
The strengthening affect that fluoride has on the teeth is only of value when
the teeth are developing in children. Only minute quantities are requir ed for
this.
An excess intake of fluoride can be harmful, as it causes the teeth to become
‘mottled’ with dark brown spots.
5.
Copper
Functions
 Component part of several enzymes – one of the most important one being
the enzyme that catalyses the oxidation of ferric to ferrous iron, so copper
helps the absorption of iron.
 Copper is an important component of superoxide dismutase, an enzyme
involved in antioxidant reactions.
 Copper participates in immune system function, red and white blood cell
maturation, blood clotting, bone strength, brain development and
cholesterol and glucose metabolism.
 Copper is part of an enzyme that forms cross -links in collagen and elastin
– connective tissue proteins.
Sources
Shellfish, liver, kidney, lean meat, cereals, nuts, bread, dried fruit.
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Effects on health and development
Several groups may also be at risk of a deficiency, namely:
 infants fed on a milk diet too long
 chronic malabsorption syndrome
 kidney dialysis patients.
Sufferers from Menke’s syndrome (a rare hereditary disorder that is
associated with reduced copper uptake) and Wilson’s disease (an inherited
disease where excess copper accumulates in the brain and causes neurological
damage) show low blood copper levels in spite of an adequate daily intake.
Micronutrients – vitamins
Fat-soluble vitamins
1.
Vitamin A
Sources
Found as vitamin A (retinol) in butter, milk, cheese, eggs and oily fish and
vitamin A (beta-carotene) in yellow, green and orange coloured fruit and
vegetables.
Effect on health and development
General use
 Vitamin A has antioxidant properties which act in body cells
removing free radicals – important for middle aged/elderly who may
be more at risk from cancer/disease. It is important to teenagers to
reduce the risk of cancers/CHD in the future.
 Necessary for formation of visual purple – a pigment found in the
retina that is necessary for vision in reduced light.
 Vitamin A is also essential for the maintenance of healthy skin and
surface tissues, particularly the most mucous membranes su ch as the
cornea at the front of the eye and lining of the respiratory and
digestive tract.
(a)
Children
 Lack of vitamin A in the diet of children reduces the rate of growth.
Retinol is essential for the growth and metabolism of all body cells.
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(b)
Pregnant women
 Vitamin A can be toxic for the foetus in high quantities. A
relationship has been suggested between high intakes of vitamin A
during pregnancy and defects in babies. Pregnant women should
avoid foods high in vitamin A, especially liver.
There is little evidence of a deficiency in the UK, although some groups
can be at risk due to a reduced absorption, namely:
 suffers of cystic fibrosis
 people with chronic liver disease
 people with coeliac disease.
A deficiency can cause:
 night blindness
 xerophthalmia
 the formation of plugs of keratin in the skin’s hair follicles.
Refer to Antioxidants – role in health.
2.
Vitamin D
Sources
Main sources are margarine, oily fish, eggs, fortified breakfast cereals and
sunlight.
Effects on health and development
General use
 Necessary for the growth and maintenance of bones and teeth in
teenagers and children.
 Required for the absorption of calcium from the intestines.
 Acts to maintain a constant level of calcium from the intestine.
 Needed for the uptake of calcium and phosphorous by the bones and
teeth.
(a)
Children
 Young babies and children who are protected from the sun must have
adequate dietary supplies to allow skeletal development.
 Children receiving an inadequate supply of vitamin D may develop
rickets (see calcium notes).
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(b)
Teenagers/adults
 Promotes quicker healing of fractures, which active teenagers may be
more prone to.
 Bone density formed during teenage years – vitamin D helps
absorption of calcium and so prevents osteoporosis in later yea rs.
 The elderly, who may be less mobile or house bound, must also
ensure adequate dietary supplies to keep bones strong and prevent
osteoporosis/osteomalacia.
An excess of vitamin D is toxic as it results in an excess absorption of
calcium into the blood. The extra calcium is deposited in the lungs and
kidneys and can cause death.
Recent research has indicated that vitamin D deficiency may be a
contributing factor to some cancers (breast, colon and prostate) and
multiple sclerosis.
3.
Vitamin E
Sources
Found in wheatgerm, vegetable oils (eg sunflower), nuts, wholegrains, green
vegetables, margarine and egg yolk.
Effects on health and development
General use
Vitamin E has an important role as an antioxidant. Free radicals, produced as
a result of normal chemical reactions in the body, can damage the lipids (fatty
compounds) found in cell membranes. The free radicals oxidi se the lipids,
forming peroxides. This lipid peroxidisation can cause damage to the cell
membrane and leaking of the cell contents, which in turn is thought to
increase the risk of inflammatory diseases such as rheumatoid arthritis.
Peroxides may also play a part in the information of ‘plaque’ in artery walls ,
which can lead to CHD. Vitamin E lipids, especially polyunsaturated fatty
acids (PUFA) protect against free radical damage.
Free radicals may also damage molecules inside the cell such as DNA and
proteins. Cells will damage DNA are more prone to cancer. Vitamin E is
therefore thought to give some protection against some forms of cancer.
Deficiency of vitamin E does not normally occur in humans although it has
occurred in premature babies fed on an infant formula deficient in vitamin E.
It has also occurred in some people unable to absorb and utilise vitamin E
adequately – these people developed nervous system problems.
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High doses may decrease the symptoms of neurological disorders, slow the
progress of Parkinson’s disease and improve mobility for arthritis sufferers.
Refer to Antioxidants – role in health.
4.
Vitamin K
Sources
Found in green vegetables, cereals.
Effects on health and development
General use
 Essential for the formation of clotting agents.
 Essential for the normal clotting of blood. Insufficient level results in
defective clotting of blood and so a tendency to bleed (important after an
accident).
 Babies, particularly if they are born premature, have low levels of vitamin
K and as a result, vitamin K is now given routinely to newborn babies in
the UK to prevent the haemorrhagic disease of the newborn.
 There is increasing evidence that vitamin K is also needed to maintain
proper bone density and so reduce the risk of osteoporosis
A deficiency of vitamin K is rarely seen because the vitamin is synthesi sed by
bacteria in the digestive tract.
Water-soluble vitamins
1.
Vitamin B1 (thiamin)
Sources
Cereals, added to white flour by law in the UK, meat, breakfast cereals,
potatoes, beans, nuts and milk.
Effects on health and development
General use
 Involved in the oxidation of nutrients and the release of energy in the
body.
 During the release of energy, each reaction requires a specific enzyme –
thiamine acts as a co-enzyme for two of the reactions.
 If thiamine is deficient in the diet, glucose is only partially oxidised. The
breakdown stops at a substance called pyruvic acid. A build-up of pyruvic
acid in the blood causes muscular weakness, palpitations of the heart and
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degeneration of the nerves. This disease is called beri -beri, which is rare in
the UK but common in parts of Asia.
 Beri-beri has been found in anorexics and alcoholics. A high intake of
alcohol increases the requirements for thiamine as thiamine is needed to
break down alcohol in the body.
(a)
Teenagers/active people
 An adequate supply of thiamin is especially important for very active
people, eg teenagers, to ensure release of energy from food to avoid
lethargy and tiredness.
(b)
Elderly people
 Although they may be less active, they must have adequate supplies
to obtain energy from food otherwise they will be lethargic.
2.
Vitamin B2 (riboflavin)
Sources
Cheese, liver, kidney and eggs, milk, meat, potatoes and green vegetables.
Effects on health and development
General use
 It is required by the body to use oxygen and for the metabolism of amino
acids, fatty acids and carbohydrates.
 Riboflavin is further needed to activate vitamin B6 (pyridoxine). It helps
to create niacin and assists the adrenal gland.
 It may be used for red blood cell formation, antibody production, cell
respiration and growth.
 Vitamin B2 is required for the health of the mu cus membranes in the
digestive tract and helps with the absorption of iron and vitamin B6.
 Deficiency affects the eyes, lips and tongue. Cracks appear at the corners
of the mouth, the tongue becomes red and swollen and in severe cases,
blood vessels invade the cornea of the eye. Poor growth has also been
reported.
 Active people/teenagers must have a good intake to ensure release of
energy from food and vitamin B2 is also important during periods of rapid
growth.
3.
Vitamin B3 (niacin)
Sources
Yeast, meat, fish, cheese, pulse vegetables and cereals.
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Effects on health and development
General use
 Forms part of an enzyme system concerned in the oxidation of glucose and
the release of energy in the body cells.
Although unknown in the UK, the deficiency disea se is pellagra. Its
symptoms are:
 dermatitis
 diarrhoea
 dementia.
Active people/teenagers must have a good intake to ensure release of energy
from food.
4.
Vitamin B6 (pyridoxine)
Sources
Meat, potatoes and vegetables
Effects on health and development
General use
 It is a co-enzyme involved in the conversion of one amino acid to another.
The need for vitamin B6 is directly related to protein intake. As the intake
of protein increases, the need for vitamin B6 increases as it allows the
body to break down the protein.
 Involved with the metabolism of carbohydrates for energy production
 Vitamin B6 helps the immune system produce antibodies. Antibodies are
needed to fight many diseases.
 Vitamin B6 is essential for the proper functioning of the nervous system
 It helps haemoglobin to form.
 Vitamin B6 is required for the production of serotonin, a brain
neurotransmitter that controls our moods, appetite, sleep patterns, and
sensitivity to pain. A deficiency of vitamin B6 can quickly lead to
insomnia and malfunctioning of the central nervous system.
 Common symptoms of vitamin B6 deficiency can include depression,
vomiting, anaemia, kidney stones, dermatitis, lethargy and increased
susceptibility to diseases due to a weakened immune system.
 Infants suffering from vitamin B6 deficiency can be anxious and irritable,
and in extreme cases may develop convulsions.
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5.
Vitamin B12 (cobalamin)
Sources
Offal, meat, liver, milk, yeast extract.
Effects on health and development
General use
 Works with folic acid for red blood cell information.
 Needed for the metabolism of amino acids as well as other enzyme systems
throughout the body.
 Involved in more than one enzyme system in the body.
 Vitamin B 12 is essential for the nervous system. A deficiency may cause
neurological symptoms due to inflammation of the nerves (neuritis).
Symptoms include altered or reduced sense of touch, less sensitivity to
vibrations, tingling in the hands and feet, muscle weakness and
psychological symptoms such as memory loss, confusion and depress ion.
 A deficiency of vitamin B12 causes pernicious anaemia. This is when the
normal division of red blood cells is disrupted so that they enter the
bloodstream at an early stage, when they are bigger and fewer than normal.
Prolonged deficiency in pregnancy is a risk factor for neural tube defects
in the newborn.
Vegans who eat no animal produce of any kind are the only people in whom a
dietary deficiency of vitamin B12 has been observed since this vitamin is
only found in foods of animal origin. For absorp tion of this vitamin a
substance secreted by the cells of the stomach, called the intrinsic factor,
must be present. Lack of the intrinsic factor is the common cause of
pernicious anaemia, which occurs in the elderly and in people who have
Crohn’s disease.
Folic acid
Sources
Folic acid, known as folate in its natural form, is one of the B group of
vitamins. Folate is found in small amounts in many foods. Sources include
liver, green leafy vegetables such as broccoli, potatoes, kidney, nuts, pulse
vegetables, breakfast cereals, flour and cereal foods.
Effects on health and development
General use
 A dietary deficiency causes a type of anaemia (megaloblastic anaemia) in
which the red blood cells become enlarged and cannot give up their
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oxygen properly to the cells. It works together with vitamin B12 to form
healthy red blood cells.
 Folic acid acts as a back up if iron is lacking in the diet and so prevents
anaemia.
 Required for the release of energy from food, particularly amino acids.
(a)
Children
 A deficiency may result in slow growth – needed for normal growth
in babies and young children.
(b)
Teenagers
 Required for normal growth in children – important during teenage
growth spurt.
 Maintains muscle tone – important for active, sporty teenagers.
(c)
Women/pregnancy
 All women likely to become pregnant should increase folic acid
intake – from the start of trying to conceive until at least the 12th
week of pregnancy.
 Increased folic acid during pregnancy may prevent neural tube
defects (spina bifida) in babies.
Normal cooking destroys 80% of the folate in vegetables and with longer
cooking and keeping hot there may be complete destruction. The increase in
take-away food consumption may mean that many people have low intakes.
Research is being undertaken into the possibility that low intake of folic acid
may increase the risk of heart disease and cancers.
Vitamin C (ascorbic acid)
Sources
Fruit, vegetables.
Effects on health and development
General use
 Necessary for the formation of collagen – the main protein of connective
tissue, which binds body cells together.
 Involved in healing of wound/sores, prevents scurvy.
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 Vitamin C has antioxidant properties – assists vitamin E in its role as an
antioxidant.
 Shown to reduce cancers of the digestive tract.
 Aids the absorption of non-haem iron from the intestine and so prevents
anaemia. Converts ferric iron to ferrous to assist absorption.
Less severe or mild deficiency symptoms may include:
 fatigue, irritability, general weakness
 greater susceptibility to infection
 walls of blood vessels weaken and break in places. Blood escapes and
appears as small red spots (haemorrhages) under the skin.
(a)
Babies
 Babies being weaned at 6 months must have adequate amounts of
vitamin C to assist with absorption of iron from food.
(b)
Teenagers
 Essential that teenagers, especially girls, have adequate vitamin C to
keep iron absorption and to prevent anaemia.
 Blood volume is expanding due to the rapid growth spurt in
teenagers.
 Necessary for healing cuts and wounds – teenagers with active
lifestyles may be more at risk from injury.
 Antioxidant properties are beneficial to teenagers to help prevent
cancers/CHD in later life.
 Required to make connective tissue which binds body cells together.
(c)
Adults
 Antioxidant properties beneficial to middle aged/elderly at risk from
CHD/cancer.
 Mild scurvy, delayed wound healing may occur in some long -stay
geriatric patients due to eating institutional food in which there is
little vitamin C left after cooking.
Refer to section on Antioxidants – role in health.
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Resource management
Content
Elaboration
Food science: the nature of food
constituents in relation to their
properties in food manufacture
In-depth study of nutrients, their
function and the effect on the health
and development of individuals.
 Antioxidants – role in health
The damage which can be caused to the body by free radicals and the
importance of vitamins and minerals in protecting against such damage has
recently aroused interest.
A daily diet high in antioxidants is good insurance. It is a way you can help
protect yourself against the two main killer diseases of Western countries –
cancer and coronary heart disease – as well as protecting eyes from macular
degeneration and it claims to hold back the age ing process.
Studies consistently show that people who have high intakes of
phytochemical-rich fruit and vegetables have lower levels of cancer and heart
disease.
What are antioxidants?
Antioxidants are substances that act as the body’s first line of defence against
unwanted damage. They are either produced in the body or obtained from the
food we eat. The three best known antioxidants are:
 vitamin C
 vitamin E
 carotenoids (vegetable source of vitamin A).
Other very important antioxidants include:
 minerals – selenium, zinc, copper, manganese (often key components of
enzymes)
 enzymes – superoxide dimutase (containing copper or manganese),
catalase, glutathione peroxides (containing selenium)
 flavonoids and a large amount of natural plant compounds
(phytochemicals).
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Compound(s)
Found in
Flavonoids*
Tea, wine, grapes, apples, onions, berries
Isoflavones
Soy beans, tofu, soy drink, other beans
Lignans
Flaxseed, oilseeds, brans, beans, vegetables, fruit
Carotenoids*
Orange and red fruit, yellow, orange and green
vegetables
Indoles and iso-thiocyanates
Cruciferous vegetables, such as broccoli
Sulphides
Cabbage, cauliflower and turnip
Phyates*
Garlic, onion, leeks, cruciferous vegetables
*Most common.
What do antioxidants do?
 Antioxidants neutralise or scavenge (‘gobble up’) substances called free
radicals that would otherwise damage cells, membranes and DNA.
What are free radicals?
Free radicals are electronically unstable molecules that can easily react with
and damage other molecules. They are formed both inside and outside the
body.
 In the body, they are formed as a by-product of metabolism whenever
oxygen is involved. The more oxygen we use, the higher the level of free
radicals produced in the body.
 During normal metabolism, a small proport ion of free radicals are formed
but they are immediately rendered harmless or ‘quenched’ by vitamins,
minerals and enzymes.
 Externally they are left behind in a variety of situations, eg by smog,
cigarette smoke, pollution, ozone, solvents, pesticides and the Sun’s
ionising radiation.
What do free radicals do?
Free radicals can damage cells, membranes, DNA genetic material and other
body structures in much the same way that air turns a cut apple brown or rusts
a nail or makes butter go rancid.
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Current nutritional thinking is that when the balance between free radicals
and antioxidants is skewed high, they ‘damage’ proteins, fatty acids and DNA
and so set the scene for tissue injury that eventually leads to chronic diseases
like cancer, heart disease, macular degeneration of the eye and cataracts.
They may also contribute to the ageing process and early senility.
Free radicals can damage cell membranes. Cell membranes contain lipids,
some of which are unsaturated, and these lipids react with free oxygen
radicals to become lipid peroxides, the same reaction as rancidity in fat. The
effect on the cell is to damage the barrier between its content and tissue fluid
– this results in mixing compounds which are usually separate and so normal
function is disturbed.
If free radicals are not quenched then a chain reaction can start which
produces extensive damage to tissue.
In some situations the production of free radicals increases and the protective
mechanism fails. Examples are smoking, ageing, inflammation (e g
rheumatoid arthritis), tissue injury following heart attacks and certain types
of chemical poisoning.
Nutritionists believe that free radicals cause LDL cholesterol to become
oxidised, causing it to be deposited in the walls of blood vessels and starting
the process of atherosclerosis. LDL cholesterol only becomes harmful when it
is oxidised.
Researchers at the University of Edinburgh have found large differences in
the incidences of heart disease in Britain, which have been closely liked to
differences in the intake of the antioxidant nutrients. Scotland, for example,
has the world’s highest level of heart disease, and the Scottish diet
traditionally lacks fresh fruit and vegetables, which are the best sources of
many antioxidants.
What about antioxidant supplements?
It is not enough to simply swallow a pill. Food is a complex mix of dozens of
phytochemicals, many of which exhibit antioxidant activity, like the
flavonoids in tea. This is why it is better to eat a healthy diet including lots of
fruit and vegetables, rather than a supplement.
However, some people, eg professional athletes, smokers and those living in
polluted areas, may benefit from a modest supplement programme. Because
antioxidants work best as a team, it is wise to choose one that off ers a broad
range, including vitamin C, vitamin E, zinc, selenium and carotenoids.
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Antioxidants – vitamins
Carotenoids (vegetable source of vitamin A)
Carotenoids or carotenes are coloured compounds found in yellow, green and
orange vegetables. Some carotenes, notably beta-carotenes, are converted into
vitamin A in the intestine. Carotenoids are important in their own right as
protective antioxidants.
Carotenoids
The carotenoids are a group of 500 to 600 compounds responsible for the
yellow and orange colours in fresh produce. Many have antioxidant properties
due to their highly-conjugated double bound structures. Epidemiological
evidence repeatedly links high intakes of fruit and vegetables (the major
source of carotenoids) with lower risk of cancers. One study found that
people who ate vegetables rich in carotenoids had a 43% lower risk of
macular degeneration of the eye than those who only ate small amounts.
1.
Beta-carotene is converted to vitamin A in the body and is the best
known and most abundant carotenoids. Its functions are:
 to inactivate free radicals
 to improve the immune capacity of the body
 to inhibit the early stages of tumour development .
2.
Alpha-carotene acts as an antioxidant and, like beta-carotene, is
converted to vitamin A in the body. High intakes are associated with
decreased risk of lung cancer. Best sources are carrots and pumpkin.
3.
Beta-cryptoxanthan acts as an antioxidant and, like beta-carotene, is
converted to vitamin A in the body. High intakes are associated with
decreased risk of cancer of the cervix. Best sources are oranges, orange
juice, paw-paw, peaches and other orange coloured fruit.
4.
Lutein and zeaxanthin protect the macula of the eye from
deterioration, which can be a leading cause of vision loss among old er
adults. Best sources are broccoli and dark green lettuce.
5.
Lycopene is the most powerful antioxidant of all the carotenoids.
Scientists have found that tomatoes are rich in a substance call
lycopene, one of several hundred carotenoids that are respon sible for
many of the red, orange and yellow colours of vegetables and fruit.
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Lycopene is responsible for the tomato’s rich red colour and functions
as a powerful antioxidant, even more potent than the much -publicised
beta-carotene.
Lycopene works to quench a highly-reactive free radical known as
‘singlet oxygen’. In fact, it has the greatest quenching ability and
highest antioxidant activity of all the activity of all the carotenoids.
This quenching protects cells and preserves genetic material from atta ck
by harmful free radicals generated by UV light, pollution and smoking.
Absorbing lycopene
Lycopene is better absorbed by the body when cooked. This is because
cooking and processing soften and disrupt the sturdy cell walls of the tomato,
releasing the lycopene.
In one study, volunteers were asked to consume meals containing the same
amount of lycopene from either 400 g of ripe tomatoes or 40 g of tomato
paste (heat-treated during manufacture), both served with bread and a little
oil. The scientists reported that lycopene was absorbed from both sources, but
significantly more from the tomato paste.
Health benefits of lycopene
Tomatoes and prostate cancer
High intakes of lycopene have been linked to a lower risk of prostate cancer
in men. Best sources are tomato-based products, including tomato sauce and
canned tomatoes.
A study from Harvard Medical School which looked at the diets of some
48,000 men found that those with high intakes of lycopene from a high
consumption of tomato-based foods had a much lower risk of prostate cancer.
Tomatoes, tomato sauce and pizza accounted for 82% of the lycopene in the
diets of the men surveyed.
The survey found that:
 eating more than 10 servings a week of tomato -based foods was associated
with a 35% reduction in prostate cancer risk
 eating 7 to 9 servings a week of tomato-based foods was associated with a
22% reduction in prostate cancer risk.
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Lycopene and heart disease
Lycopene is fat soluble and is carried in the bloodstream attached to the
‘dangerous’ LDL cholesterol, where it seems to work in conjunction with
vitamin E to protect LDL from oxidation. It may therefore have a positive
effect on heart disease prevention. This fits with numerous epidemiological
studies over the past 10 years showing that high intakes of fruit and
vegetables exert a protective effect against heart disease, as does vitamin E.
Lycopene’s role in fighting cancer of the lungs, cervix and digestive tract is
also being investigated.
Lycopene and sun protection
Lycopene protects the tomato from burning as it ripens in the sun, and it
appears humans can benefit in the same way. One of the early clues was that
UV rays leave beta-carotene unaffected, but significantly deplete lycopene
levels.
Some of the Sun’s damaging effects are thought to be mediated through
reactive oxygen species. Because lycopene is so good at quenching these,
nutritionists hope that lycopene may help to protect the skin against UV light
in the short term (sunburn) as well as over the long term (cumulative effects
of the sun exposure and skin cancer).
Vitamin C (ascorbic acid)
Vitamin C scavenges oxygen free radicals.
 It inhibits nitrosamine formation.
 It is an important antioxidant, especially in the regeneration of oxidised
vitamin E in membranes in the body. In this way it is important in
maintaining membrane structure.
 It has been shown to reduce cancers of the digestive tract (oesophagus,
stomach and pancreas).
 It aids the absorption of iron especially vegetable sources ( ie non-haem
iron).
Vitamin E
 Vitamin E is present in cell membranes, where it acts as an antioxidant and
quenches free oxygen radicals, protecting the lipids of cell membranes
from damage. In doing so it is rendered inactive but is restored by reacting
with vitamin C.
 Vitamin E protects LDL cholesterol from oxidation and helps prevent CHD
and certain forms of cancer.
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 Vitamin E is the major antioxidant in all cell membranes , where it
maintains the stability of fatty acids in the phospholipid layer. Vitamin E
protects bonds from polyunsaturated fat from breaking down.
Antioxidants – minerals
Selenium
 Selenium works in combination with vitamins C and E. It is a component
of the antioxidant enzymes glutathione peroxidase , which reduces
peroxides before they can attack intracellular membranes (glu tathione
peroxidase is involved in the quenching of free radicals).
 Selenium also enhances immune response.
 Best sources are seafood, liver, kidney, lean meat and whole grains,
although their content depends on the soils where they are grown.
Copper
 Copper is a component of several enzymes and as such it has an important
role in many reactions, including the quenching of free radicals.
 Copper is also involved in forming blood cells.
 Best sources are seafood, liver, kidney, lean meat, wheat bran, nuts, yea st,
cocoa powder and dried fruit.
Zinc
 Zinc is part of the enzyme superoxide dismutase . which prevents free
radicals from forming peroxides.
 Best sources are seafood (especially oysters), lean meat, chicken, milk,
whole grains, wholemeal, dried beans, lentils and nuts.
Antioxidants – enzymes
Superoxide dismutase containing copper and manganese prevents free
radicals from forming peroxides that can harm tissues.
Glutathione peroxidase containing selenium reduces peroxides therefore
preventing them from attacking cellular membranes.
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Antioxidants – flavonoids
The flavonoids found in tea are powerful antioxidants and free radical
scavengers. Flavonoids consist of a number of compounds . including
catechins. Catechins have been shown to be powerful antiox idants –
anywhere from two to six times more powerful than vitamins C and E. Diets
rich in fruit and vegetables, in tea and red wine are associated with good
cardiovascular health. Several studies have suggested that flavonoid -rich
foods are particularly cardioprotective. Tea and wine are of particular interest
as they are rich in flavonoids, particularly catechins.
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Resource management
Content
Elaboration
Nutrients and their effect on the health
and development of individuals
Inter-relationship of nutrients
Factors affecting absorption of
nutrients
Calcuim, phosphorous and vitamin D
 Calcium and phosphorous are both needed for the formation and
maintenance of strong bones and teeth. Together they form calcium
phosphate, which gives bones and teeth their hardness.
 Absorption of calcium is controlled by vitamin D. A diet lacking in
vitamin D results in poor calcium absorption and adversely affects the
formation and maintenance of strong bones and teeth.
 Without vitamin D we cannot make use of the calc ium in food.
 If blood levels of calcium and phosphorous fall too low then the hormone
produced by the parathyroid gland removes these nutrients from the bones
and teeth and puts them back into the blood.
Calcium absorption is also affected by the followin g:
 Lactose – this is a sugar present in milk and increases calcium absorption
on hydrolysis.
 Protein – the amino acids formed from protein as a result of digestion
combine with calcium to form soluble salts and these salts are very readily
absorbed.
 Phytic acid – this is found in wholegrain cereal foods and combines with
calcium in a form that prevents calcium being absorbed.
 NSP cannot be digested in the human digestive system as the NSP and
calcium bind together. Much of the calcium in fibrous foods is ma de
unavailable to the body.
 Fats, particularly saturated fatty acids, form insoluble soaps with calcium
that cannot be absorbed.
 Oxalic acid, which is particularly high in rhubarb and spinach, also
interferes with calcium absorption.
ACE vitamins
 The best-known antioxidants, which help to neutralise potentially
damaging free radicals in the body, are vitamins A, C and E.
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 A diet high in ACE vitamins is thought to reduce the risk of CHD.
 Vitamin E improves the activity of vitamin A in the body.
 Vitamin C helps the action of vitamin E in the body, eg after vitamin E has
been used by the body and is finished, vitamin C works on th e vitamin E to
recycle it.
Iron, vitamin C and folic acid
 Depending on the food source of iron, not all of the iron which is eaten is
actually absorbed by the body. Iron in our food is ferric iron and cannot be
absorbed until it is changed to ferrous iron.
 Vitamin C is required to change iron into its more easily absorbed form ,
ferrous iron, and also to ensure an adequate supply of red blood cells. If
vitamin C is lacking in the diet then the iron will not be changed into
ferrous iron.
 Folic acid also improves the red blood cell count – if iron is lacking then
folic acid can supplement the supply.
 Folic acid can also help prevent megaloblastic anaemia if the iron
absorption is poor.
Vitamin B complex and carbohydrate
 Vitamin B complex acts as a link in a complex chain of chemical reactions
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which release energy from carbohydrates so adequate supplies of B
complex vitamins must be present in the diet.
The B complex vitamins have a role in the release of energy from food so
that it can be used by the body.
The more energy is needed by the body, eg by a sports person, then the
more vitamin B complex is required to release the ener gy.
Vitamin B1 (thiamine) helps release energy from glucose.
Vitamin B2 (riboflavin) and vitamin B3 (niacin) help release energy from
food.
Iron, NSP and phytic acid
 Too much indigestible NSP in leafy vegetables and fresh fruit can bind
with iron and not allow it to be absorbed into the bloodstream.
 Phytates found in food containing NSP will remove iron from the body in
waste materials.
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 Phytates form insoluble complexes with iron in the small intestine , which
then inhibit iron absorption.
 Phytic acid in wholegrain cereals binds with iron to prevent absorption.
 Iron absorption is also affected by tannin found in tea.
Water and NSP
 NSP absorbs water in the gut. The bulk and softness of the waste matter is
affected by this absorption of the water.
 If there is no NSP in the waste matter, no water is absorbed into it and the
waste matter is then difficult to get rid of from the body (constipation).
 If there is plenty of NSP and the waste matter absorbs water, it becomes
bulkier, softer and much easier to pass out of the body.
 NSP is of great importance in the diet as it absorbs a lot of water and binds
the other food residues to itself. This ensures that the faeces are soft and
bulky and so can pass easily out of the body easily and quickly.
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Resource management
Content
Elaboration
Nutrients and their effect on the
health and development of
individuals
Health and dietary diseases
Bowel disorders
Cancer
Coronary heart disease
Dental decay
Diabetes
Hypertension
Iron deficiency anaemia
Obesity and weight reduction
Osteomalacia, osteoporosis
Reference should also be made to sections on Health of individuals, Main
nutrients, Micronutrients and Antioxidants
Bowel disorders
NSP is of great importance to health as it:
 aids the removal of waste products, which could be harmful or toxic, from
the body
 absorbs a lot of water ensuring that the faeces are soft and bulky, enabling
them to pass along the intestine by means of peristalsis
 helps prevent various bowel disorders, including constipation, diverticular
disease, bowel cancer and haemorrhoids (piles).
There are two types of NSP:
(i)
Soluble NSP
This type of NSP is thought to slow down the digestion and absorption
of carbohydrates and so help to control blood sugar levels . It is useful
for diabetics.
(ii)
Insoluble NSP
Insoluble NSP absorbs water and increases in bulk, helping the gut stay
in good working order.
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Constipation
Many people suffer from constipation. The faeces become very hard
and move slowly through the intestine, and a lot of effort is required
to remove them. Abdominal discomfort and a general feeling of ill health accompany this condition.
Diverticular disease
 If extra strain is put on the muscular walls of the small intestine because of
constipation, then diverticular disease may de velop.
 If the faeces are small and hard due to a lack of NSP and water, then the
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muscular walls of the intestine have to work harder to move the faeces
along.
This results in increased pressure in the intestine. Pouches of the bowel
lining are forced through weak spots in the intestinal walls to form small
pockets, called diverticula, and where they occur the subject is sa id to be
affected by diverticular disease.
Diverticula usually occur in the lower part of the large intestine. They may
start to harbour bacteria, which are usually excreted.
Symptoms are acute abdominal pain, flatulence and diarrhoea.
Diverticular disease usually only appears in people who have a diet low in
NSP and are less active.
An increase in consumption of refined and convenience foods also
contributes to this condition.
Irritable bowel syndrome
Irritable bowel syndrome (IBS) is a poorly understood disorder. It has been
estimated that IBS affects about 20% of adults in the UK and the condition
affects three times as many women as men. The symptoms are abdominal
pain and discomfort, and a change in bowel habit, which may be either
constipation or diarrhoea. The pain is usually related either to eating or going
to the toilet. These symptoms can also be features of other bowel disor ders
and so IBS is often diagnosed by a process of elimination.
 People with constipation-dominant IBS may benefit from an increase in
dietary fibre.
 People with diarrhoea-dominant IBS may benefit from a decrease in
insoluble fibre.
Some sufferers associate their symptoms with eating particular types of food
but there is not enough scientific evidence to suggest that specific exclusion
diets are routinely beneficial.
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Some evidence suggests a number of IBS sufferers may be sensitive to
excessive amounts of caffeine and to sorbitol (a sugar alcohol that is found
naturally in fruits such as plums, apricots, cherries and apples and is also
used in some products in place of sugar) and should try limiting intakes of
foods and beverages containing these compou nds.
There is some research into the effect probiotics may have on IBS. As the
evidence is currently limited, no clear guidance can be given although
anecdotal evidence suggests some individuals may find they benefit.
Haemorrhoids (piles)
These may be caused by the increased effort required to remove hard faeces
in constipation sufferers
Bowel cancer
It is suggested that people today do not eat enough NSP and this is the cause
of many bowel disorders and bowel cancer.
Many foods eaten today are refined. This means that they have much of their
NSP content removed, as in white flour and white rice. It is important to
ensure the bowel regularly gets rid of poisonous waste as this will help
prevent bowel cancer.
Cancer
Research figures have stated that more than one in three people in the UK
will develop cancer at some point during their lifetime. As result of rising
rates of obesity, it has been estimated that there could be 12,000 cases of
weight related cancer every year by 2010.
To reduce the risk of cancer it is advisable to avoid smoking, keep body
weight within the healthy range for height, maintain regular physical activity,
keep alcohol consumption to a moderate level, and eat a balanced diet with
plenty of fruit and vegetables and moderate amounts of red and processed
meats.
What is cancer?
The body is made up of small units called cells. New cells are constantly
produced to replace cells that have become worn out or damaged. New cells
are also made during growth, eg during infancy and child hood. Normally, the
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body regulates the growth of new cells but occasionally abnormal cells are
produced.
These abnormal cells do not function properly and if they are not destroyed
by the body’s surveillance system, they may develop (mutate) and also
rapidly increase in number, causing cancer. The abnormal cells may also
spread to other parts of the body and multiply there.
Cancer can occur in different parts of the body. In the UK, the most common
cancers in men are lung cancer, prostate cancer and co lon cancer. The most
common cancers in women are breast cancer, lung cancer and colon cancer.
Factors involved in cancer
The risk of cancer is affected by the following:
Genetic factors – people who have a family history of a particular cancer are
more likely to develop it themselves.
Hormonal factors – the risk of some cancers, eg some breast cancers, is
linked to levels of certain hormones in the body.
Environmental factors – a range of environmental factors affect the
development of a large proportion of cancers, to varying degrees. Examples
are tobacco smoke, diet, alcohol, some chemicals, and many other aspects of
lifestyle, eg physical activity and body weight.
Diet and cancer
Health experts agree that diet plays an important part in cancer ri sk.
Approximately 30% of cancers could be prevented by dietary means in
Western countries. Despite this, consumers continue to eat a diet high in fats,
sugars, salt, processed foods and red meats. Research has linked all these
foods with an increased risk of cancer.
Diet has a greater influence on some types of cancer than others. The
strongest links are with some cancers of the gastrointestinal tract, eg cancer
of the mouth, throat, stomach and large bowel (colon) , and some hormonerelated cancers, eg breast.
Large intakes of salt have been linked to stomach cancer. Research carried
out in the UK has indicated that a high intake of salt and preserved foods
increases the risk of stomach cancer. Some foods are obvious sources of salt ,
such as crisps, bacon, processed meats and junk/snack foods, but it is the salt
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content of supposedly ‘healthy’ food, eg cereals and yoghurts, that causes
concern as these are less obvious sources to consumers.
Experts agree that the main cause of stomach cancer is infectio n with
Helicobacter pylori. High salt intake appears to interact with this bacteria to
influence the risk of stomach cancer. Stomach cancer rates are highest in
where there are high salt intakes, such as Japan and China.
Several studies have suggested that a high consumption of red and/or
processed meat is associated with increased risk of colon cancer in both men
and women. High intakes of saturated fats may be linked to breast cancer.
A number of studies suggest that fruit and vegetables reduce the risk of
certain cancers, including mouth, throat, stomach and bowel cancers. In
developing countries, cancers of the mouth, throat and oesophagus are
thought to be related to a diet low in fruit and vegetables. Some studies
suggest a reduced risk of stomach cancer with higher intakes of fruit and
vegetables.
One of the mechanisms proposed to explain the beneficial effect of fruit and
vegetables is via the antioxidants they contain, such as vitamin C, carotenoids
and other plant phytochemicals.
Although dietary intakes and blood levels of antioxidant nutrients such as
vitamin E and beta-carotene have generally been associated with a lower risk
of cancer (eg lung cancer), some studies have not generally supported a
beneficial effect. Fruit and vegetables also c ontain other components that
might be of benefit in cancer prevention. For example, there is thought to be
a beneficial effect of dietary fibre on bowel cancer risk.
Body weight
Researchers have estimated that excess weight causes 3.8% of cancer s.
According to a Cancer Research UK survey, only 29% of overweight or obese
people were aware that being overweight increases the risk of developing
cancer despite the fact that it is now well established that being obese
increases the risk of developing several types of cancer.
Being overweight and obesity are established risk factors for cancers of the
oesophagus, bowel and kidney. Overweight women also have an increased
risk of womb cancer.
Obesity increases the risk of breast cancer in post -menopausal women by
50%, probably due to associated increases in hormones. There is also
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evidence to suggest that obesity and being overweight increase the risk of
gallbladder and pancreatic cancers.
The risk of colon cancer increases by approximately 60% in men and 30% in
women with a body mass index (BMI) greater than 28.5, compared with a
BMI under 22.3 (a healthy BMI is between 20 and 25). Obese men have a
90% increased risk of dying from colon cancer.
Weight is also a factor in cancer survival. Obese or overweight people are
less likely to survive than those of a healthy weight. This may be due to the
increased difficulty in being able to diagnose cancer in overweight people and
so the cancer may be more advanced before it can be treated.
Physical activity
Being physically active is important for weight control and may have other
benefits (eg increased bowel movement, enhanced immune function, raised
levels of various hormones and signalling molecules in the body that can
result in a sense of well-being). Research consistently shows that physical
activity reduces the risk of colon cancer, and there is some suggestion that
physical activity can reduce the risk of breast cancer initially and from
recurring.
Alcohol
In addition to smoking, alcohol is one of the mai n risk factors for cancers of
the mouth, throat and oesophagus. Alcohol is also the main diet -related risk
factor for liver cancer and this is thought to be through its effects on liver
cirrhosis. There is also a large amount of research to show that the r isk of
breast cancer increases with increasing amounts of alcohol consumption:
there is a 7% increase in risk for one alcoholic drink every day (compared to
none). The effects of alcohol on breast cancer risk may involve increasing
oestrogen levels. Some recent studies also show that alcohol might increase
the risk of colon cancer.
Coronary heart disease
Coronary heart disease is the term used to describe the gradual narrowing of
the coronary arteries. These arteries supply blood and oxygen to the heart
muscle.
The arteries usually narrow because of a build up of a fatty type substance
(cholesterol) within the inner lining of the coronary artery and this slows
down blood circulation and the amount of oxygen that reaches the heart. This
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build up is usually caused by an increased concentration of cholesterol in the
blood.
There are two degrees of coronary artery disease:
 In one, the blood flow is reduced to the point where the increased demand
of hard work cannot be met and this results in angina .
 In the other the coronary artery becomes completely blocked , usually by a
clot, and this is called coronary thrombosis.
Angina
The pain is usually linked to exertion and forces the patient to stop. It passes
within a few minutes. The pain is a result of no t enough oxygen and nutrients
being supplied to the heart muscle and so the muscle becomes starved.
Coronary thrombosis (heart attack)
Deposits of cholesterol are found in the lining of the arteries. These deposits
may be quite thick, roughen the interior of the arteries and make the risk of
blood clots more likely. If the clot formation blocks the coronary artery then
part of the heart muscle is deprived of blood and oxygen. This may lead to
heart failure and the patient dies. Some heart attacks only cau se a small
amount of damage to the heart muscle and people can recover quite quickly.
A heart attack is usually accompanied by severe pain. Obstruction of an
artery to the brain is one of the causes of a stroke, ie cerebral thrombosis.
Risk factors which may contribute to coronary heart disease include the
following:
Dietary factors
(a)
Obesity caused by over eating
 Too much food – this may lead to obesity. Being obese can make it
more difficult for blood to pump through the heart increasing the risk
of high blood pressure and CHD.
 Being overweight is a major risk factor and leads to problems such
as high blood pressure or diabetes, both of which are risk factor s that
can lead to heart disease.
(b)
Too much total fat intake
 Eating too much fat in total can cause obesity, which is a
contributory factor in heart disease.
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 Traditional cooking methods such as frying may increase fat intake .
Some people may find difficulty in changing to more healthy
methods.
(c)
Too much saturated fat intake
 Too much saturated fat mainly from animal origin increases the level
of cholesterol in the blood. Cholesterol is made in the liver in our
bodies using the fat we eat, especially saturated fats. High blood
cholesterol is thought to be one of the risk factors in the
development of heart disease.
 Cholesterol is ferried around the bloodstream by proteins called
lipoproteins. LDL is often branded bad cholesterol because high
levels of LDL increase the risk of heart disease. LDL carries
approximately 70% of the blood cholesterol.
 A high level of LDL cholesterol in the blood (especially if it is
oxidised) can lead to fatty deposits in the arteries known as plaque ,
which cause the artery to narrow, increasing the risk of blood clots
and blockage of the artery.
 Too many saturated fats may also make the blood more sticky and
likely to clot.
(d)
Too much trans fatty acids
 These increase blood levels of LDL cholesterol and may reduce
levels of good cholesterol and so increase the risk of heart disease .
(e)
Too few polyunsaturated fats
 Omega-3, a polyunsaturated fatty acid, is found mainly in oily fish
such as mackerel, sardines and pilchards. Omega -3 reduces the risk
of blood clots forming, so reducing the risk of a heart attack.
(f)
Too few monounsaturated fats
 Monounsaturated fats reduce LDL (high levels increase risk of
CHD), which tend to form fatty deposits on artery walls and increase
the risk of blood clotting and increase HDL (high levels reduce risk
of CHD), which help remove fats cholesterol to the liver where it i s
broken down into bile.
(g)
Too much salt
 Eating too much salt may cause high blood pressure. If blood
pressure is too high for too long, the arteries can be damaged. This
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 can make them brittle and liable to clog with cholesterol. If this
happens in one of the arteries that supplies the heart with blood, the
result could be a heart attack.
(h)
Too much sugar
 If too much sugar is eaten then this can result in obesity, high blood
pressure and heart disease.
 Dietary sucrose can also cause disturbances i n the body that are
characteristics of type 2 diabetes. CHD is a common cause of death
in people with diabetes.
(i)
Too little NSP
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(j)
Soluble NSP found in oats, fruit, lentils and peas have been shown to
reduce blood cholesterol levels.
Soluble fibre lowers the levels of cholesterol in the blood by binding
with bile salts, which are made from cholesterol, thus preventing reabsorption.
High intake of starchy carbohydrate foods promotes a feeling of
fullness, provides a steady supply of energy helping blood sugar
levels thus reducing the risk of snacking on high -fat foods, which
would increase fat intake and risk of obesity.
Too little fruit and vegetables/antioxidants
 Fruit and vegetables are good sources of antioxidant vitamins – the
ACE vitamins. The antioxidant vitamins neutralise the free radicals ,
which may damage cells and tissues within the body and this gives
us some protection against heart disease.
 ACE vitamins slow down the rate at which LDL cholesterol is
deposited on the artery walls, helping to prevent heart disease.
 ACE vitamins reduce the number of damaging free radicals in the
body. It is thought that free radicals cause some cholesterol to
become oxidised, causing them to be deposited on the walls of blood
cells and starting the process of atherosclerosis.
Lifestyle factors
(a)
Cigarette smoking
 This is the largest known contributory factor to CHD and increases
the chance of blood clots forming.
 Smoking causes the blood to thicken, increasing the tendency to clot.
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 Smoking constricts (narrows) the arteries, reducing the blood flow to
the heart.
 The nicotine in tobacco smoke increases the pulse rate and raises
blood pressure. The carbon monoxide content of cigarette smoke cuts
down the oxygen in the blood so the heart has to work harder .
 Smokers need a high intake of ACE vitamins as smoking increases
the number of free radicals in the body. Free radicals damage cells
and tissues, increasing the risk of heart disease.
 Smoking introduces harmful free radicals into the body and destroys
antioxidant vitamins, which could then lead to a build up of
cholesterol in the arteries.
(b)
Heredity
 Some families may inherit high risk factors such as a liking for fatty
foods and this increases the risk of heart disease. Poor eating habits
developed in childhood are often carried into adulthood.
 Genetic conditions may produce high blood cholesterol levels.
(c)
High alcohol intake
 Alcohol contains a high number of calories , which will cause
overweight and possibly high blood pressure and so increase th e risk
of heart disease.
(d)
Lack of physical exercise
 Regular exercise benefits the heart by increasing stamina and
strengthening the heart muscle, making it more efficient.
 Regular exercise reduces stress and lowers blood cholesterol levels –
both of which can contribute to heart disease.
 Exercise helps weight loss and maintenance.
 Exercise strengthens the vessels leading to heart muscle and so
reduces the likelihood of developing CHD.
 Lack of physical exercise may cause energy intake to exceed energy
output, thus increasing the risk of obesity and CHD.
 Regular exercise has a beneficial effect on blood cholesterol levels.
 A sedentary lifestyle from an early age contributes to overweight.
(e)
Emotional stress
 People who are tense, impatient and anxious may be more likely to
suffer from heart disease.
 Emotional stress – stress can increase blood pressure, which
increases the risk of CHD.
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 Blood pressure also tends to rise under stress and this could damage
the artery walls, particularly if they are clogge d with cholesterol.
The heart then has to pump harder to force blood round the body.
(f)
Gender
 More men than women tend to have heart disease but it is affecting
an increasing number of women.
 Women under 40 years may be protected from heart disease by the
hormone oestrogen. After the menopause, when oestrogen levels are
reduced, cholesterol levels rise and the risk of heart disease
increases.
(g)
Food choices linked to lifestyle
 Less food eaten within household environment therefore less control
and responsibility for its nutritional content. People tend to eat out
and purchase more fast foods.
 High consumption of convenience foods and takeaways due to
inability or unwillingness to cook and lack of time. Many of these
foods have a high fat content, which contributes to CHD.
 Children have much more choice in relation to food and often make
inappropriate choices that may lead to obesity and so increased risk
of CHD in later life.
Dental decay
Foods that contain a high proportion of sugar are reduced to a very sticky
mixture when they are chewed and mixed with saliva. Even after swallowing,
sugary particles are left sticking to the teeth. If the teeth are not thoroughly
cleaned afterwards, traces of very sticky foods, such as toffees, may be
detected clinging to the teeth as long as 24 hours later. Bacteria, which are
normally present in the mouth, attack the sugary residues and change them to
acids. The acids gradually dissolve small areas of teeth’s protective covering,
the enamel. This is the way tooth decay begins.
Theoretically, sugar in any form will cause tooth decay, but in practice sugars
contained naturally in foods, eg fruit, have less effect. Sucrose is the sugar
that contributes most to dental decay. It is the frequency and amount of Non
Milk Extrinsic Sugars (NMES) – mainly confectionary, soft drinks and table
sugar – that are the main causes of tooth decay.
Other carbohydrates, especially cooked starch ( eg present in crisps), which
can be broken down by enzymes in saliva to component su gars, may also
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damage teeth, although to a much lesser degree. This is because starch has to
be broken down before fermentation can occur.
Fresh fruit is not strongly associated with caries. This is thought to be due to
the fact that the sugars in fruit are held in the cells of the fruit and are not
released until chewing breaks down the cells. However, the acidity of some
fruits and fruit juices (eg oranges, lemons, limes) can cause dental erosion –
the progressive loss of enamel from the tooth – in certain circumstances, eg if
the juice is swished around the mouth or fed in a baby’s bottle.
In a fruit juice the sugars are no longer held in the cells of the fruit.
Consumption of fruit juice is therefore potentially associated with developing
caries, especially if the juice is in contact with the teeth for a long period of
time.
Another factor that affects the risk of developing caries is the retentiveness
(stickiness) of the carbohydrate. Foods such as dried fruit or toffees may stick
to the teeth and so reduce the pH in the mouth for a longer time than would
occur with less sticky food. It is important that teeth are brushed regularly
each day, preferably with a fluoride toothpaste, to remove any food sticking
to the teeth or trapped between the teeth. Regular tooth brushing and the use
of dental floss also removes the dental plaque coating the tooth surface and
gum margins, which constrains the bacteria responsible for dental decay.
Regular visits to the dentist are important to ensure that dental healt h is
maintained.
The most effective means of reducing dental caries that is available to the
individual is to control sugar intake. The most important factor is not the total
amount of sugar that is consumed but the number of times that sugar enters
the mouth. Sugar eaten at meals is not as damaging as sugar eaten between
meals as snacks. The main aim in sugar control for the prevention of decay is
to persuade people to limit their consumption of food and drinks containing
sugar to meal times.
Prevention of dental caries
Diet
 Foods rich in calcium, phosphorous and vitamin D must be eaten to give
teeth their hardness.
 Vitamin C must be included in the diet to keep the gums healthy.
 Crunchy foods, like apples and carrots, should be eaten regularly to
exercise the gums and prevent infection.
 Eating too much salt/sodium in the diet could lead to extraction of calcium
from the bone, thereby weakening the teeth.
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 Saliva plays an important part in that the flow of it over the teeth not only
helps cleaning but helps to neutralise the acid. This is why foods that
require a lot of chewing and are not sticky are better because they increase
saliva production.
 ‘Diet’ drinks lower the intake of sugar but are a major cause of tooth
erosion (tooth wear) due to the acidity of the drinks. Water should be the
preferred drink.
 Reduce NME sugars intake by:
– limiting consumption of sugar, sugary foods and drinks that cause a
build up of plaque, which attacks the enamel
– avoiding sugary and sticky snacks between meals as this p rolongs
exposure to the acid, which causes a build up of plaque
– becoming aware of the foods with ‘hidden’ sugar – read the labels on
food products
– increasing use of fresh or dried fruit as sweetening agents on breakfast
cereals, in baking and also as a snack food as they are intrinsic sugars
that do not produce the same amount of acid in the mouth
– avoiding grazing on biscuits and juice – continual contact with sugar
– avoiding sweet foods last thing at night
– not missing breakfast – more sweets may be eaten as snacks
– eating fresh fruit and vegetables as snacks
– not being influenced by adverts for sweet foods
– not giving children sweets when they have been upset or hurt
themselves or as a reward as this will encourage a sweet tooth in later
life.
Diabetes
What is diabetes?
Diabetes (or diabetes mellitus) is a condition in which the amount of glucose
in the blood is not controlled. The process of moving glucose from the blood
into the body’s cells relies on a hormone called insulin. When insulin levels
are too low or are not effective, blood glucose levels can rise and this may
result in diabetes.
Diabetes develops when the body cannot use glucose properly. Around 1.4
million people in the UK have diagnosed diabetes, of whom around 1 million
have type 2 diabetes. In addition, there are a large number of people who may
have unrecognised diabetes.
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Insulin
The hormone insulin is made by the pancreas, a gland lying just behind the
stomach. Insulin is one of the hormones that help to control the lev el of blood
sugar, glucose, which is a vital fuel for cells. Insulin clears glucose from the
blood and helps it to enter the cells, such as in muscles, liver and adipose
(fat) tissue. It is important that insulin works properly because both low and
high levels of blood sugar are harmful to the body. A low level of blood
glucose is called hypoglycaemia, while a high level is called hyperglycaemia.
The symptoms
The main symptoms of untreated diabetes are:





increased thirst
the need to pass urine much more often, especially at night
weight loss
tiredness
blurred vision.
Type 1 diabetes
What is type 1 diabetes?
Type 1 diabetes is also known as insulin-dependent diabetes. It is an autoimmune condition in which the immune system of the body ( which protects
the body against infection and disease) turns against itself. As a result most,
or all, of the insulin-producing cells of the pancreas are destroyed and the
pancreas is not able to produce enough insulin. How the insulin -producing
cells are damaged is not very well understood but it may be due to a viral or
other infection, coupled with a genetic predisposition. Without insulin, the
body is neither able to use glucose as a fuel for the cells (causing rapid
weight loss) nor control the level of blood glucose . As a result, the level of
blood glucose can become too high.
Treatment
It is important to maintain the body’s blood glucose level in order to
eliminate the symptoms and prevent the long-term consequences of high
blood glucose levels, particularly circulation problems and damage to nerves,
kidneys and eyes. Type 1 diabetes is managed by injections of insulin
coupled with a healthy diet. People with diabetes are given individual advice
on how to inject themselves with insulin, what type of diet to eat an d how to
check the level of glucose in their blood and urine.
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Insulin injections
Insulin injections are vital for survival. Insulin cannot be taken by mouth
because it would be destroyed in the stomach. There are different kinds of
insulin treatments available. Insulin is usually injected one to four times per
day depending on the type of insulin (quick-acting or slow-acting) and the
daily routine of the person. The amount and timing of insulin injections are
adjusted depending on the timing, amount and type of food eaten (mostly the
amount of carbohydrates, ie starches and sugars) and the frequency, timing
and quantity of exercise taken. The aim is to avoid wide swings in the blood
sugar level after and between meals, as these are associated with a great er
risk of complications later in life.
Type 2 diabetes
What is type 2 diabetes?
Type 2 diabetes (also sometimes referred to as non -insulin dependent
diabetes) occurs when the body does not produce enough insulin or the
insulin produced does not work properly (this is known as insulin resistance).
Type 2 diabetes usually develops in middle -aged people (over the age of 40)
and later life but also recently amongst teenagers in the UK. It can be
managed by diet and exercise alone or in combination with ta blets or insulin
injections.
If type 2 diabetes is treated properly from the early stages of the disease, the
risk of any long-term complications is reduced. These complications include
heart disease, stroke, high blood pressure, circulation problems and damage
to the nerves, kidneys and eyes. Regular medical check -ups are very
important for people with diabetes and also for those who are at high risk of
diabetes.
Eating a healthy balanced diet, taking regular physical exercise and
maintaining a healthy body weight can help to prevent or delay the onset of
type 2 diabetes.
Prevalence of type 2 diabetes
Type 2 diabetes is increasing rapidly both in the UK and in the world in
general. This is thought to be linked with the fact that obesity is increasing .
There are currently around 1.4 million people with diagnosed diabetes in the
UK, of which around 1 million have type 2 diabetes. In addition, there are a
large number of people who may have unrecognised diabetes.
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Who is at risk of type 2 diabetes?
There are several risk factors for type 2 diabetes of which inherited
predisposition, obesity and physical inactivity are the most important.
 Hereditary factors are more significant when diabetes is diagnosed at a
younger age. When diabetes is diagnosed at an older age, lifestyle factors
are more relevant.
 The rise in obesity rates in the UK is a main contributor to the rapid
increase in the prevalence of diabetes. Most people with newly diagnosed
type 2 diabetes are overweight or obese (BMI of 30 or over).
Dietary factors can contribute to the development of type 2 diabetes. The
most significant factors are a diet high in energy and fat (especially
saturates), and low in dietary fibre. This kind of diet is harmful because it
causes weight gain and also impairs insulin action.
Lack of exercise is harmful because it can promote weight gain and impair
insulin action. Regular exercise has many benefits. Apart from improving the
ability of insulin to act, it also helps overweight people to lose weight.
Everyday activities, like cycling or walking to work, or walking up the stairs
instead of taking the lift, can be helpful.
Treatment
Changes to diet and physical activity are the two main approaches in the
treatment of type 2 diabetes. The aim of the treatment i s to help the people to
control their blood glucose level and also to help weight loss. Usually it is
possible to control diabetes by diet and activity but some people may also
need tablets or insulin injections; about 30% of cases are managed by diet and
insulin injections. The recommended diet for patients with type 2 diabetes is
the same as the healthy diet recommended for all people.
The dietary advice for people with diabetes has changed considerably over
the last century. People with diabetes used to be told to eliminate all sugar
and sugary foods from their diet. This resulted in people with diabetes buying
special diabetic foods to replace everyday sugar -containing foods. Today,
however, the most important message for people with diabetes is to eat
healthily, in exactly the same way that is recommended for the whole
population, ie a balanced diet based on starchy foods and plenty of fruit and
vegetables, and low in fat, salt and sugar. This means that a small amount of
sugar and sugar-containing foods can be eaten, preferably as part of a healthy
meal. Special diabetic cakes, biscuits or pastries are of no particular benefit
and as well as them being more expensive, they may contain a lot of fat.
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People with diabetes should try to maintain a heal thy weight and eat a diet
that is low in fat (particularly saturates) and salt but contains plenty of fruit
and vegetables (at least five portions a day) and starchy carbohydrate foods
such as bread, rice and pasta (particularly wholegrain versions).
People with type 2 diabetes are at greater risk of cardiovascular disease than
the general population. Dietary advice should therefore focus on reducing
cardiovascular disease risk.
Alcoholic drinks
Advice on alcoholic drinks is the same as for the general population (up to 3
units a day for women and up to 4 for men). Alcohol can have both hypo - and
hyperglycaemic effects, depending on the amount consumed, the type of drink
and whether it is consumed with a meal. In studies in people with diabetes,
alcohol had no acute effect on blood glucose or insulin levels, indicating that
such beverages should be regarded as additional items rather than
substitutions for foods.
Hypertension (high blood pressure)
Everyone has blood pressure. The pressure is created b y the heart’s constant
pumping of blood around the body.
Exercise, excitement, anger or anxiety all make the heart beat faster and
increase blood pressure temporarily.
High blood pressure is often called hypertension.
High blood pressure is usually caused by narrowed or damaged blood arteries
– this means that the heart has to work harder to pump blood around the body.
When blood is forced through arteries at high pressure, it is more likely to
damage artery walls.
There are many factors which contribute to high blood pressure.
Being overweight
Excess body fat increases the risk of high blood pressure. Maintaining a
healthy body weight (for adults this means a BMI of 20 –25) by eating a
balanced diet and being physically active can protect against hyp ertension.
For those who are overweight, losing as little as 5 –10% of body weight may
lower blood pressure. Weight-reducing diets may also reduce the dose of
antihypertensive medications required to control blood pressure levels.
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Poor diet
A diet that is low in fat and includes low-fat dairy foods and fruit and
vegetables has been shown to lower blood pressure in people with or without
high blood pressure. This diet reduces the amount of fat, saturates and
cholesterol and increases the amount of potassium, magnesium and calcium.
Reducing the amount of salt in the diet also ha s a beneficial effect. The best
effect is achieved when both approaches are combined. This highlights the
importance of improving the overall diet rather than focusing on single
nutrients. Eating a healthy balanced diet will also help to maintain a healthy
body weight.
Salt
Reports conclude that sodium intake is an important determinant of blood
pressure, in part influencing the rise of blood pressure with age. As the main
source of sodium in the diet is salt (sodium chloride), it has been
recommended that people in the UK try to reduce their salt intake to 100
mmol per day.
Potassium, calcium and magnesium
An inadequate dietary intake of potassium may increase blood pressure. A
high potassium intake may therefore protect against developing hypertension
and improve blood pressure control in patients with hypertension. There is
also evidence to suggest that the effect of sodium on blood pressure may be
related to the amount of potassium in the diet and that the ratio of sodium to
potassium in the diet might be more important than the absolute amount of
either. Potassium is found in meat, milk, vegetables, potatoes, fruit
(especially bananas) and juices, bread, fish, nuts and seeds.
Studies have also suggested that ensuring an adequate amount of calcium and
magnesium in the diet is important to protect against high blood pressure, as
well as for general health. Sources of calcium include milk and dairy
products, soft bones in canned fish, bread, pulses, green vegetables, dried
fruit, nuts and seeds. Foods containing magnesium include cereals and cereal
products, meat, green vegetables, milk, potatoes, nuts and seeds.
The amount and type of fat in the diet
The amount and type of fat in the diet affects blood cholesterol levels. A high
blood cholesterol level increases the risk of heart disease and stroke and is
therefore an important consideration in people with high blood pressure.
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Omega-3 fatty acids appear to have beneficial effec ts on heart health. Studies
in which very high doses of fish oil supplements have been given to people
with high blood pressure have found reductions in blood pressure. However,
these levels of intake would not be obtained from a normal diet. More
research is needed in this area but current advice is to eat at least one portion
of oil-rich fish per week.
Lack of exercise
Regular physical activity can help to lower blood pressure and enhance
weight loss. It can also reduce the risk of heart disease : people who exercise
regularly have a 50% lower risk of dying of a heart attack. The ‘feel good
factor’ that regular physical activity brings is also beneficial and many people
use exercise as a way to reduce stress.
Excessive alcohol
Drinking too much alcohol not only directly puts up blood pressure, it can
also lead to weight gain. Excess alcohol consumption can cause resistance to
antihypertensive therapy and is a risk factor for several diseases, including
stroke, heart disease and liver disease.
Stress
Although the evidence is fairly limited, stress is often cited as a contributor
to high blood pressure.
Smoking
The avoidance of tobacco in any form is particularly important for people
with high blood pressure. Smoking damages the heart and circulation , and
increases the risk of heart disease and stroke.
Age
As people get older blood pressure rises a little as the artery walls become
less elastic.
Family history
High blood pressure is more likely if it is common within families.
High blood pressure does not usually have any symptoms, but it is important
– especially if it goes unnoticed over a long period of time. It is one of
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several risk factors which can increase the chance of having a stroke, heart
attack or kidney failure.
The risk of high blood pressure can be reduced by doing the following:
 Avoid obesity – keeping weight down helps keep blood pressure down.
 Reduce alcohol intake, if necessary, to no more than 21 units per week for






a man or no more than 14 units for a woman (one unit equa ls a half pint of
ordinary beer, a small glass of wine or a single measure of spirits).
Alcohol is high in calories and can increase blood pressure.
Add less salt to food and cut down on salty foods. This will not help
everyone with hypertension but those who take a lot of salt may well
benefit from cutting down. Research has shown that there is a link between
sodium intake and high blood pressure.
Regular physical exercise helps control stress and helps to keep blood
pressure normal.
Stop smoking. Smoking temporarily raises blood pressure. It also adds to
the damage that high blood pressure may cause to the heart and blood
vessels.
People who suffer from hypertension should avoid stressful situations
which are likely to raise the blood pressure because this may lead to a
heart attack or a stroke.
It should also be noted that reducing fat intake, particularly saturated fat,
is recommended because the cholesterol found in saturated fats can narrow
arteries and so restrict blood flow.
Potassium tends to reduce blood pressure, so a diet which is high in, for
example, cereals, fruit and vegetables, ie is high in potassium, will have a
beneficial effect on blood pressure.
Iron deficiency anaemia
 The human body contains about 4 g of iron.
 Iron is a vital part of haemoglobin, the pigment in red blood cells that is
responsible for transporting oxygen from the lungs to the cells of all body
tissues.
 Oxygen is needed by all body cells to break down nutrients and obtain
energy.
 If you become too short of iron you start making red blood cells containing
less haemoglobin. That means your body has to work harder to supply you
with enough oxygen. This extra work can leave you feeling weak,
constantly tired and short of breath – all of these things are symptoms of
iron-deficiency anaemia. Resistance to infection is reduced and there may
be poor regulation of body heat.
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 Extra iron that is not needed for haemoglobin is stored in the liver, spleen
or bone marrow, ready to be used if there is a shortage in the diet.
Prevention of iron-deficiency anaemia
 The daily food intake must include sufficient iron to maintain the normal
level of haemoglobin in the blood. Eggs, red meat, especially liver and
kidney, fortified bread and breakfast cereals, dried fruit, beans, lentils and
leafy green vegetables all contain iron.
 Foods rich in vitamin C should be eaten alongside these iron-rich foods to
help absorption.
 Iron from food sources not linked with NSP or phytates (eg meat) is more
easily absorbed by the body.
 A course of iron tablets may also be taken to make up a shortage of iron.
Reasons why iron may be lacking in the diet
 Snacking and grazing throughout the day rather than traditional meals
could reduce iron intake.
 If people are not aware of nutrition or are lacking in the s kills to prepare
iron-rich foods then sufficient iron may not be included in their diet.
 Less red meat may be eaten for health reasons – to reduce saturated fats or
for moral or religious reasons.
 Dark green vegetables can be unpopular, particularly with younger age
groups.
 If a good supply of fruit and vegetables supplying vitamin C is not eaten
then absorption of iron will be affected.
How much iron is needed?
Most people lose about 1 or 2 mg of iron a day from their bodies, but to
replace that you need to eat foods containing a greater amount – about 8 to 15
mg – because only a small proportion of the iron in food is absorbed by our
bodies.
Certain groups of people may be more likely to suffer from iron deficiency
anaemia:
(a)
Adolescent girls and women who are menstruating – it is estimated
that 30 mg of iron is lost during menstruation and this will be more if
periods are heavy and prolonged.
(b)
Pregnant women – During pregnancy, a total of about 400 mg of iron
is supplied to the unborn child and the actual birth causes the loss of a
further 250 mg. However, the increased needs of pregnancy for iron
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should be met without a further increase in iron as menstruation has
stopped and the mother’s store of iron can be used. Dietary supplements
may be needed by mothers with low iron stores, eg teenage mothers.
(c)
Babies are born with an iron store, which is needed because milk has a
low iron content. This store will only last about 4 months so it is
important to introduce iron-rich foods quite soon (about 4 months) to
prevent anaemia. This can be done by giving enriched cereals, pureed
vegetables, minced meat, etc.
It is particularly important to ensure that babies and young children get
enough iron. There seems to be a critical period – between 6 months
and 5 years – when a shortage of iron in the diet can cause a small but
permanent reduction in a child’s learning ability.
(d)
Teenage boys require plenty of iron because during growth the volume
of blood increases. There has been quite an increase in the number of
teenage boys suffering from anaemia, particularly during the ‘growth
spurt’ period. As their bodies grow so does the volume of blood
required. They may also require extra iron for muscle growth and also
to supply oxygen to the muscles during sporting activities.
(e)
Older people – The main reasons for anaemia in the elderly are either
that they cannot afford iron-rich foods or because they are often living
alone and cannot be bothered or do not have the strength to prepare
adequate meals. Also the high consumption of tea can be factor, as the
tannin in tea prevents absorption of iron.
(f)
Vegetarians may have difficulty in obtaining enough iron as the main
food sources are those not consumed by them, eg red meat, liver,
kidney, eggs. The other good sources are perhaps those that are slightly
less popular, eg green leafy vegetables, dried fruits, etc, and more of
these are required to give the same quantity of iron and this can make
diets bulky.
Vegans may absorb less iron due to the high phytic acid content of NSP
foods such as cereals.
(g)
People living on low incomes – Low income may mean that this group
of people cannot afford iron-rich food, they may not be sufficiently
motivated to prepare adequate iron-rich meals and they may have poor
facilities for storage, preparation and cooking of foods.
(h)
Athletes may have a higher loss of iron from the body due to muscular
activity.
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Too much iron
Too much iron can be more harmful than too little. Our bodies regulate the
amount of iron so for the great majority of people there is no risk of
poisoning from even the largest amounts of iron that you are ever likely to
get from food. The larger amounts concentrated in iron tablets , however, are
not so safe.
Iron tablets are a common cause of poisoning in young children. The tablets
can often look like sweets, and the amount of iron in just a few can be
harmful for children. If you are taking an iron supplement it would be wise to
treat it as a medicine and lock it away safely.
Obesity
A major dietary problem in the UK today is obesity. Obesity caused by excess
body fat is a hazard to health. There are no exact figures to tell us what an
individual of a given height, with a certain bone structure, should weigh.
Tables which have recommended weights give a good guide, and it is always
clear when a person is so grossly overweight that they become obese. Usually
obesity is caused by long-term overeating. Your energy requirement dictates
what you can eat and this varies from person to person and becom es less as
you grow older.
A way of measuring body fatness is to use the BMI, which is a measure of a
person’s body weight in kilograms divided by the square of their height in
metres. The BMI classification is used internationally and the World Health
Organization defines obesity as being a BMI of over 30. A BMI of 25 –30 is
classed as overweight.
Reasons for the rise in obesity:
1.
Dietary reasons
High sugar and/or fat diet
 Sweets and chocolates contain large quantities of fat or sugar which
can contribute to weight gain, especially if eaten daily between
meals or instead of meals.
 Drinks with added sugar, eg sweetened fruit drinks/fizzy drinks can
contribute to weight gain.
 Fast food and snack consumption are both high. These are popular ,
especially with teenagers, and have a high fat and energy content.
 If energy intake from food is more than energy output over a period
of time then this leads to obesity.
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Reluctance to eat fresh fruit and vegetables
 Prefer to snack on high fat and sugar foods rather than fruit and
vegetables.
 There may be limited availability in the home due to cost or lack of
knowledge about how to prepare these foods.
Increased consumption of pre–prepared convenience meals in the
home
 Increasing tendency for these meals to be use d in the home as an
alternative to home-made meals. These foods can be high in fat and
sugar.
Huge increase in range of convenience food and fast -food eating
outlets
 More takeaway meals are eaten by families, especially teenagers.
These can have a high energy value.
Diet low in NSP and total complex carbohydrates
 Both these foods are filling, so if there is insufficient consumption
then people may be more likely to snack on high-fat and high-sugar
foods due to feelings of hunger. If this snacking continued then
obesity may result.
Lack of sensible eating habits
 Eating habits and food fads are developed in childhood and are
difficult to change. Overweight parents often have overweight
children and although it could be argued that body type could be
hereditary, the cause is probably due to family eating habits.
 A high–fat, high-sugar diet in childhood leads to problems like
obesity in later life.
 People tend to adopt eating habits when young and as they get older
they continue to eat the same amount, but th eir physical and energy
output are reduced.
 Erosion of family mealtimes means ‘grazing’ is more common, often
on high-fat and high-sugar snacks.
2.
Consumer attitudes
 Poor diet in Scotland is now a historical fact; fried and high -fat
foods are traditional. In the past they were required for warmth but
this is less true now so they contribute to obesity.
 Some consumers are anxious about adaptations made to food
products to make them healthier, eg fat replacers and sugar
substitutes, so they continue to buy higher fat and sugar varieties.
 Some consumers just do not want to change.
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3.
Lack of exercise and physical activity
 Increased use of cars by all members of the family, eg teenagers do
not walk to school. Fewer journeys made on foot or by bicycle.
 Lack of sports facilities locally or the cost may be too high.
 Sedentary lifestyle, particularly of young people – increasing number
of teenagers just watch TV or play computer games.
 Obesity is less likely to found in people that have jobs involving
hard physical work and who lead active lives.
 Parents may be inactive and do not encourage teenagers to take part
in sports outside school.
 Parents may be concerned about the safety of children outdoors so
physical activity, such as playing in the park or street, is not
allowed.
 Poor weather in Scotland is not always conducive to outdoor
excercise so the population generally may be less active. Poor
weather also encourages the use of cars.
4.
Advertising and media
 The majority of advertising of food products is for those which can
contribute to obesity; very little for healthier options.
 Special offers, eg buy one get one free, can encourage overpurchasing of foods, which if unhealthy can promote overeating.
 Use of cartoon/TV characters on foods can encourage pest er power
to prevail and foods that appeal to children may well be high in
fat/sugar.
5.
Access to shops
 Larger supermarkets, which have a better range of lower fat/sugar,
higher NSP foods, are usually out of town; not all people have access
to transport.
 The rural nature of Scotland means that access to larger
supermarkets is not always easy, therefore the availability of
products that may help reduce obesity is limited.
6.
Manufacturers
 Some manufacturers are making slow progress at adapting foods to
make them lower in fat/sugar.
 New labelling schemes are not always understood fully by consumers
so may be ignored.
7.
Family income
 Where income is limited, cheaper, poorer quality foods , often highfat, high-sugar foods, may be bought in preference to more expensive
protein foods or fruit and vegetables.
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8.
 Lack of money discourages experimentation with new foods that
could be wasted so poor diet continues.
 Lower fat/sugar foods often more expensive.
 Fresh foods have a limited shelf life and are more prone to waste.
 Fresh fruit and vegetables are expensive.
 Higher income may mean more disposable income being given to
teenagers, providing more opportunity for them to buy snacks and
fizzy drinks.
 Higher income – more convenience-type foods may be bought to
accommodate a busy lifestyle. These foods can be high in fat/sugar.

Skills/knowledge
 Lack of preparation and cooking skills means a reluctance to prepare
fresh foods such as fruit and vegetables, so convenience/takeaway
foods, which can be higher in calories, are consumed.
 Children learn poor eating habits from parents so problem continues
down the generations.
 Messages often confusing and contradictory – as a result people stick
to what is familiar, which leads to obesity.
 General lack of nutrition education may mean people do not actually
know what to do to reduce their risk of obesity.
9.
Cooking facilities
 Poor housing and limitied finances often equal poor cooking
facilities. Improving them to facilitate home cooking is not always
seen as a priority so higher fat convenince foods and takeaways may
be consumed more regularly.
 Poor facilities reduce the ability and willingness to prepare fresh
foods, which exacerbates the obesity problem.
10.
Lifestyle
 Lack of time for shopping and food preparation – quick-to-prepare
meals that require little food preparation and cooking are preferred.
Convenience foods are often high in fat and sugar.
 Increased ownership of microwaves and freezers makes convenience type foods very useful for busy families.
 The huge increase in convenience foods and eating outlets can lead
to people eating too many convenience or takeaway foods, which
again often have a high energy value.
11.
Psychological factors
 If a person is anxious, depressed, bored or lonely, then she/he may
find eating a great comfort and overeat.
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12.
Taste
 Both fat and sugar add flavour to food so by reducing them foods
become less appealing and consumers revert to varieties that are
higher in fat and sugar.
Childhood obesity
Obesity in children is rising rapidly and is a major concern. Figures show
that:
 about one in 10 children aged under 10 is obese
 one in four 11–15 year olds is obese
 by 2050 half of the UK’s young boys and one in five young girls will be
very overweight.
Children are now less active and are more likely to spend their spare time
watching television and playing computer games. A healthy diet and lifestyle
would help towards reducing obesity levels in children.
Parents must play a role in preventing children becoming overweight at an
early age by ensuring that sensible eating habits are encouraged.
How can parents help?
Helping the development of sensible eating habits
 Parents’ eating habits are passed on to their children and children learn to
like foods made by their parents; there is an opportunity to make the
foods eaten lower in fat.
 Lifelong eating habits are established in childhood so it is vital that good
habits are established in childhood.
 Encouraging the eating of a variety of foods at an early age is likely to
promote good eating habits throughout life.
 Eating the correct balance of foods/nutrients contributes to the
maintenance of a healthy weight/reduces the risk of obesity.
 Eating proper meals will reduce the need to snack on fatty sugary foods
that are high in calories.
 Children may be unwilling to try new, healthy options if they have not
seen and tried them at home, so parents should offer a wide range of
foods to children.
 Lack of food preparation skills leads to a reliance on convenience foods,
which may be high in fat or sugar and low in fruit, vegetables or NSP.
 The financial situation of the family may mean that foods consumed at
home are limited. These limited choices may be a cause for similar
unhealthy choices at school.
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
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Sensible eating habits during pregnancy reduce the risk of childhood
obesity.
Educating children by encouraging them to work with food and help cook
their own meals can lead to an informed attitude towards food and its
function in the body.
Education from parents – teaching children about nutrition and teaching
about foods and food choices.
Promoting positive attitudes towards food
 If food is used as a comfort or as a treat, it can lead to eating for the
wrong reasons and may lead to obesity.
 Encouraging meals to be a social occasion means more time is spent
eating so there is a greater feeling of fullness, which lead to less
snacking/grazing.
 If meals are seen as social occasions then there is less eating on one’s
own, which is often when overeating takes place.
 Family meals encourage children to try new foods so this could reinforce
good eating habits.
Ensuring regular exercise patterns
 Parents can encourage children to exercise more by setting a good
example and exercising themselves.
 Parents can walk children to school instead of taking the car.
 Parents can take children to the park, swimming lessons , etc and make
exercise part of their life.
Health problems associated with obesity
Heart and circulatory systems
 Overweight people are more likely to develop high blood pressure.
 High blood pressure can lead to CHD as the heart has to work harder to
supply extra the oxygen and nutrients needed by tissues.
 Strokes.
 Angina.
 More likely to suffer from varicose veins, haemorrhoids, swollen ankles.
 A tendency towards high blood cholesterol levels.
Joints
 Problems with hip, knee and back joints and arthritis as extra weight is
placed on muscles and skeleton if overweight.
 More likely to develop osteoarthritis in the knee joints.
Metabolic
 Type 2 diabetes.
 Stones in the gall bladder.
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 More chance of digestive glands being overworked or ceasing to function.
Cancer
 In women, increased risk of cancer of the ovaries, cervix and breast
cancer.
 In men increased risk of prostate and bowel cancers.
Other
 Breathless during exertion as heart and lungs have to work harder to
maintain oxygen supply. Likely to tire more easily.
 Reduced mobility and agility.
 Psychological problems, such as low self-esteem and lack of confidence
can result from obesity. Unwilling to take part in exercise due to body
size, which then makes the problem of obesity worse.
 Overweight people often suffer from psychological disorders such as
depression and anxiety. Obese people may be laughed at by their peer
group.
 Dental caries if obesity is caused by eating a high sugar diet.
 Complications can occur during surgery with obesity.
 People who are overweight can experience difficulties during pregnancy
and childbirth.
 Reduced fertility.
 Menstrual irregularities.
Weight reduction
The only way to reduce weight is to use up excess fat. This m eans that daily
food intake must be reduced so that the excess body fat is used to meet the
body’s needs for energy. While on a reducing diet meals still must be well
balanced: although the energy intake is reduced the essential nutrients must
be provided.
The following help to reduce weight:
 Decrease kilojoule intake without decreasing bodily activity.
 Cut down on fat and sugar intake.
 Use complex carbohydrates as a filling energy source. They contain fewer
calories, gram for gram, than foods with a high fat content, and give a
feeling of fullness and satiety.
 Do not cut down on essential body-building foods such as protein but
watch that excess protein is not eaten, as this will contribute to weight
gain if it is not used up as energy.
 Eat plenty of fresh fruit and vegetables to provide bulk in the diet without
providing excessively high calorie intake.
 Establish a good eating pattern of three meals per day.
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 Try not to miss a meal as hunger may increase the likelihood of unhealthy
snacking.
 Avoid eating between meals – if hungry have fruit.
 Avoid frying as a method of cooking – choose to grill foods instead of




frying.
Do not go on a crash diet as a steady weight loss is much healthier.
Avoid ‘gimmick’ diets – these do not establish good eating habits.
Adopt a new pattern of sensible eating and keep to this after weight loss,
rather than reverting to bad eating habits.
Establish a regular pattern of exercise.
Osteomalacia
If absorption of calcium and phosphorus from the small intestine is reduced
due to a lack of vitamin D, too much phytic acid or too much NSP, there will
be insufficient to maintain the strength of bones. Bones become weak, fragile
and may break easily. Strength of teeth is also not maintained.
This is an adult form of rickets, more common in the elderly, which can
result in serious fractures, after even a minor fall.
The reasons for osteomalacia in the elderly are not exercising enough, not
getting out in the sunshine, particularly in winter, not being able to get out ,
not being able to afford some of the required foods and often being on drugs
for a medical condition.
Osteoporosis
Osteoporosis – brittle bone disease – is on the increase, affecting men as well
as women.
Osteoporosis develops gradually and unnoticeably over many years; diet and
lifestyle now can affect the chances of getting it later on.
What is osteoporosis?
 Osteoporosis means porous bones.
 Bones are made up of collagen for flexibility and calcium for strength. In
osteoporosis bones lose some of their internal collagen and calcium,
making them weak and liable to break – hence the disease can also known
be known as ‘brittle bone disease’.
 Osteoporosis is not a problem of too little calcium but of the way we use
and keep that calcium in our bones.
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 Most people do not know they have osteoporosis until they have a minor
fall or make an awkward movement and end up fracturing a bone.
 Some people with osteoporosis experience chronic backache or notice they
are getting shorter and developing a stoop as the bones of t heir spine
become weakened and compacted. Losing 5–10 cm in height is common,
and the spinal curve may develop into a ‘ dowager’s hump’.
 This shortening of the body means there is less room for internal organs –
the stomach can be forced up into the chest and the abdomen pushed
forward. This can cause chest pain and a feeling that food is stuck behind
the breast bone.
The bone cycle
 Bone tissue is constantly turning over, being broken down and rebuilt.
 Bones stop growing in length around late teens and e arly 20s or early 30s.
 At this age bones reach their peak bone mass (PMB) – their maximum size
and density. Potential PBM is determined by heredity, but whether or not
this potential is achieved depends on diet and lifestyle factors. After the
mid 30s bone density declines – loss of bone occurs at the rate of 0.3% of
PMB per year.
 Teenagers with low calcium intakes may not reach their potential PBM. At
risk are those who avoid dairy foods, are slimming or rely heavily on junk
food containing little calcium.
 In women during the 5 years following the menopause the loss is greater
due to the lack of the hormone oestrogen. Hormone replacement treatment
assists in the prevention of loss of calcium from bones and stimulates the
production of new bone, therefore helping to ensure that bones do not
become brittle and helping to prevent osteoporosis.
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Factors that may help to reduce the risk of osteoporosis
Factor
Explanation
Calcium-rich
diet
A high intake of calcium in childhood and
teenage years, which are the main stage of
bone development, helps to raise PBM and
prevent osteoporosis in later life
Calcium is necessary for the formation and
maintenance of bones
Vitamin D helps the absorption of calcium
in the body, which helps achieve PBM and
prevent osteoporosis
Phosphorus combines with calcium to
produce calcium phosphate, which is the
main substance necessary for bone
hardness/strength and helps to prevent
osteoporosis
Exposure is essential for the syntheses of
vitamin D
Vitamin D is essential for calcium
absorption in the intestine, helping bone
formation and preventing osteoporosis
A high intake of fat/saturated fat may lead to
poor calcium absorption, which could
contribute to osteoporosis
This will slow down the loss of calcium
from the bones and help prevent
osteoporosis
Regular exercise will increase bone
density/stimulate bone formation and reduce
the risk of osteoporosis
In young people, exercise may raise PBM,
reducing the onset of the osteoporosis in
later life
In adults, exercise protects against bone
loss, reducing the risk of/delaying the onset
of osteoporosis
The nicotine in cigarettes can cause actual
bone loss so stopping smoking can reduce
bone loss and prevent osteoporosis
As alcohol is a toxin to bone cells, increased
alcohol consumption may start to decrease
bone mass, which may lead to osteoporosis
Vitamin D- rich
diet
Phosphorousrich diet
Exposure to
sunlight/ultravi
olet light
Lowfat/saturated fat
intake
Low
salt/sodium
intake
Regular
exercise
Not smoking
Low alcohol
intake
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A balanced diet
Low intake of
junk foods
A healthy body
weight
Low NSP
intake
Low phytic acid
intake
Include lactose
in the diet
Include protein
in the diet
An unbalanced diet may result in a diet low
in calcium/vitamin D/phosphorus and bone
density may be affected, increasing the risk
of osteoporosis
Junk foods tend to be lacking in calcium and
so do not allow PBM to develop
This increases the risk of osteoporosis
Junk foods tend to be high in fat/saturated
fat, which may hinder calcium absorption,
leading to an increased risk of osteoporosis
Obesity puts an extra strain on the bones and
indicates an unbalanced diet that may be
short in calcium, leading to an increased risk
of osteoporosis
High intake of NSP in the diet hinders the
absorption of calcium and contribute to
osteoporosis
High intake of phytic acid in the diet hinders
the absorption of calcium and contribute to
osteoporosis
Lactose in the diet assists the absorption of
calcium and help achieve PBM and help
reduce the risk of osteoporosis
Protein in the diet assists the absorption of
calcium and helps achieve PBM, helping to
reduce the risk of osteoporosis
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