Learning Objective: Nutritional Biochemistry
1. Outline the basic food groups and understand the proportions that constitute a
balanced diet
The five basic food groups are as follows;
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Breads, cereals and grain products
Fruit and vegetables
Milk and milk products
Butter and table margarine and oils
Meat, fish, nuts, poultry, eggs, lentils and legumes
The recommended daily intakes of each of the group will depend upon the individual’s
age and/or sex. The following are recommendations taken from the State of Victoria’s
‘Better Health Channel’ website;
How many serves children and adolescents need each day
Bread, Cereals,
rice, pasta,
noodles
Vegetables,
legumes
Fruit
Milk,
yoghurt,
cheese
Children 4-7
years
3-4
4
2
3
1/2 -1
1-2
Children 8-11
years
4-6
4-5
1-2
3
1-1 1/2
1-2
Adolescents 1218 years
4-7
5-9
3-4
3-5
1-2
1-3
Children and
adolescents
Meat, fish,
Extra
poultry,
foods
eggs, nuts,legumes
Sample serves from the Australian Guide to Healthy Eating.
How many serves women need each day
Bread, cereals,
rice, pasta,
noodles
Vegetables,
legumes
Fruit
Milk,
yoghurt,
cheese
Meat, fish, poultry,
eggs, nuts,legumes
Extra
foods
Women 19-60
years
4-6
4-7
2-3
2-3
1-1 1/2
0-21/2
Pregnant
4-6
5-6
4
2
1 1/2
0-21/2
Breastfeeding
5-7
7
5
2
2
0-21/2
60+ years
3-5
4-6
2-3
2-3
1-1 1/2
0-2
Women
Sample serves from the Australian Guide to Healthy Eating.
How many serves men need each day
Men
Bread, cereals, rice,
Vegetables,
Fruit
Milk,
Meat, fish, poultry,
Extra
pasta, noodles
legumes
19-60
years
5-7
6-8
60+ years
4-6
4-7
yoghurt,
cheese
eggs, nuts,legumes
foods
3-4
2-4
1 1/2-2
0-3
2-3
2-3
1-1 1/2
0-2 1/2
Sample serves from the Australian Guide to Healthy Eating.
Extra Foods are classified as foods that do not contain significant amounts of nutrients
and are not ‘core’ to the diet.
Another common way to see the recommended intakes of the food groups is in the
Health Eating Pyramid;
Sources:
 http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Food_variety_
and_a_healthy_diet?open
 http://www.google.com.au/imgres?imgurl=http://www.diabetesdiabeticdiet.co
m/images/food_pyramid.JPG&imgrefurl=http://www.diabetesdiabeticdiet.com/f
ood_pyramid.htm&h=392&w=493&sz=43&tbnid=GM435a7b2g1a_M::&tbnh=10
3&tbnw=130&prev=/images%3Fq%3Dfood%2Bpyramid&usg=__ML2RLqgIaJIQC
GIHYd75ZHY15bY=&ei=ViWlSevWJoTO6gOcnITWAg&sa=X&oi=image_result&res
num=4&ct=image&cd=1
2. Understand the terms macronutrients, micronutrients and essential nutrients
and their purpose
Macronutrient
A macronutrient is any of the nutritional components of the diet that are required in
relatively large amounts. For example, proteins, carbohydrates, fats, water and
macrominerals. Macrominerals are those required in amounts of 100 milligrams or more
per day. Examples of these are calcium, phosphorus, sodium and chloride.
These macronutrients are required in order to ensure the normal growth and
development of an individual.
In question 3, the specific functions of some of these macronutrients are described.
Micronutrient
A micronutrient is an organic compound that is essential only in minute amounts for the
normal functioning of the body. Examples of a micronutrient include zinc or iodine.
Essential Nutrients
Essential nutrients are basically those nutrients that must be gained from a dietary
source. The body is not capable of synthesizing essential nutrients. They are also
essential for the normal functioning of the body.
Essential nutrients include the following;
 Water
 Carbohydrates
 Proteins (essential amino acids: isoleucine, leucine, lysine, methionine,
phenylalanine, threonine, tryptophan, valine, histidine (in infants only))
 Fats (essential fatty acids: linoleic acid and linolenic)
 Vitamins
 Minerals
3. Describe Carbohydrates, Lipids and proteins and understand their role and
function
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Carbohydrates
Carbohydrates are also known as Sugars and Starches, and are the fundamental energy
source for our bodies. They can be simple molecules (glucose, sucrose and fructose) or
complex conglomerations of these two basic units.
Breads, cereals and leafy green vegetables are the major sources of Carbohydrates.
Carbohydrates yield the most amount of energy when metabolised by the body, and
travel in the blood as a ready source of energy for cells.
Monosaccharides
 Monosaccharides (simple sugars)/ Basic Units/ building blocks of
carbohydrates (3-7 carbon atoms)
 Every carbon in a monosaccharides (except for those with an
aldehyde or ketone group) will have a hydroxyl group
 Examples of Monosaccharides include Glucose (the most
common and most important), Fructose or Galactose
 Monosaccharides form the basis for all other sugars
 They share the general formula of C6H12O6
Glucose Molecule
Disaccharides
 Formed through the combination of any 2
monosaccharides. In the process of combining the 2
monosaccharides to make the disaccharide, a water
molecule is released
 Sucrose (glucose + fructose), lactose (glucose +
galactose) and maltose (glucose + glucose) are all
examples of disaccharides
 Also called sugars
Polysaccharides
 Polymers with more than 6 monosaccharides
 The most important polysaccharides are; starch,
glycogen, pectin and cellulose (dietary fibre)
 The human body is incapable of digesting cellulose as it
lacks the necessary enzymes, however other
polysaccharides can be important sources of glucose for
the body
Glucose for energy can be obtained 3 ways;
a) Digestion and absorbtion of sugars and starches
b) Glycogen stores
c) Amino acids (when other sources fail)

Verbascose
Lipids
Lipids, like carbohydrates, contain the elements of carbon, hydrogen and oxygen and is
the general name to describe fats, oils, fatty acids, phospholipids, steols, glycolipids and
waxes.
The most common lipid is the triglyceride, which is comprised of a glycerole molecule
and three fatty acids.
Lipids are important energy sources in the body. They provide
almost double the energy of proteins or carbohydrates and are
generally stored for times of need. They are stored in the adipose
tissues of the body.
Other functions of lipids include;
 Act as an insulating layer to the body to retain body heat
 Protection of vital organs
Triglyceride
 Lipids act as a carrier of fat-soluble vitamins such as A, D, E and K
 Preventing hair and skin from becoming too dry
 Provide the essential fatty acids of linoleic and linolenic acids which are needed for
the health of nerve coverings
 Lipids act as a precursor of prostaglandins, which work to regulate body processes
such as smooth muscle action, blood flow and secretions of various substances (such
as stomach and nasal secretions)
 Phospholipids can form organized structures when suspended in water solution (ie.
Cell membrane)

Proteins
Proteins are large carbon chains which contain carbon,
hydrogen, oxygen, nitrogen and sulfur. These elements
form together to make amino acids, which are the basic
building blocks for all proteins. They are second only to
water in the concentration of the body and can be found
in many forms.
Amino Acid
There are 22 amino acid groups, but all have at least one amino group (NH2) and at least
one carboxyl acid group (COOH).
Proteins are made up of strings of amino acids and are known as polypeptides, as they
are linked by peptide bonds. These bonds form between the –NH2 from one amino acid
and the –COOH group from the adjacent amino acid.
Polypeptide chains can take on one of two forms;
a) Globular proteins will have a 3D shape. Examples will include haemoglobin
and myoglobin
b) Fibrous proteins are straighter and more elongated than globular proteins.
Gluten (found in wheat) is an example
The functions of the protein are quite extensive;
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They have a growth and repair role within the body. The body breaks down
dietary proteins into amino acids and then uses these to synthesize new proteins
Proteins contribute to the structure of the body in terms of cell membranes,
connective tissues such as elastin and collagen, muscles, hair and nails
Many enzymes and hormones (both proteins) are involved in metabolism.
Thyroxine, insulin, and adrenalin are examples of hormones involved in the
regulation of fundamental body processes. Enzymes are needed for the digestion
and metabolism of carbohydrates, lipids and proteins. Enzymes also catalyse
many processes in the body, whilst antigens aid the body in fighting infection
Proteins can act as a secondary energy source. During starvation, the body will
break down muscle protein into amino acids and use them in metabolism. When
this is occurring, proteins cannot be used for other essential functions, such as
growth and repair
4. Outline the dietary goals and targets and recommended daily allowances for
Australia
The National Australian Guidelines were developed by the National Health and Medical
Research Council (NHMRC) as a result of an increased number of diet related disorders
that Australians suffer. They were first developed in 1979 and have undergone a
number of iterations.
They include recommendations such as the following;
 Enjoy a wide variety of nutritious foods
 Eat a diet low in fat and, in particular, low in saturated fat
 Maintain a healthy body weight by balancing physical activity and food intake
 Limit intake of alcohol
 Eat of moderate amounts of sugars
 Choose low salt foods and use salt sparingly
 Encourage and support breast feeding
 Eat food containing calcium (particularly important for girls and women)
 Eat food containing iron (particularly important for girls, women, vegetarians
and athletes)
For the full text; http://www.nhmrc.gov.au/publications/synopses/_files/n33.pdf