PHYSIOLOGY OF NUTRITION
AND VITAMINS
MUDr. Romana Šlamberová, Ph.D.
Nutrition
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Food is any substance that can be consumed.
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Food is the main source of energy and of nutrition, and
is usually of animal or plant origin.
Food is a source of substances that are not energy and
nutrient supply, but are esencial for our life (vitamins,
salts, trace elements).
Metabolism (change) = is the biochemical
modification of chemical compounds in living
organisms and cells.
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This includes the biosynthesis of complex organic
molecules (anabolism) and their breakdown
(catabolism).
Calorie

A calorie is a unit of measurement for energy.
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The small calorie or gram calorie approximates the energy
needed to increase the temperature of 1 g of water by 1 °C. This
is about 4.185 J.
The large calorie or kilogram calorie approximate the energy
needed to increase the temperature of 1 kg of water by 1 °C.
This is about 4.185 kJ, and exactly 1000 small calories.
The amount of food energy in a particular food could be
measured by calorimetry.
Recommended daily energy intake values for young adults
are: 2500 kcal/d (10 MJ/d, 120 W) for men and 2000 kcal/d
(8 MJ/d, 100 W) for women. Children, sedentary and older
people require less energy, physically active people more.
Calorimetry
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Calorimetry is the science of measuring the heat of
chemical reactions or physical changes.
Energy moving from one place to another is called heat
and calorimetry uses the measurement of temperature
changes to track the movement of heat.
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Direct calorimetry = oxidation of substances in calorimeter or
change of water temperature induced by a body
Indirect calorimetry = measuring products of biological
oxidations (CO2, H2O, final products of protein catabolism) or
consumption of O2 (4,82 kcal freed energy / 1 litre of O2).
Indirect calorimetry
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The Respiratory Quotient is used in BMR calculations (basal
metabolic rate) and is a form of indirect calorimetry.
RQ = CO2produced / O2consumed
 RQ carbohydrates = 1
 RQ lipids = 0,7
 RQ proteins = 0,8
Basal metabolic rate (BMR), is the rate of metabolism that occurs
when an individual is at rest in a warm environment and is in the post
absorptive state, and has not eaten for at least 12 hours.

BMR = 2000 kcal/day (during sleep even lower)
The release of energy in this state is only sufficient for the vital
organs.
BMR decreases with age and with the loss of body mass. Regular
cardiovascular exercise can increase BMR. Other factors can also
affect BMR, such as illness, previous food, environmental
temperature, and stress levels.
Body Mass Index

Energy balance = balance between intake and dispensation of
energy
 Negative = consumption of inner supplies
 Positive = storage to inner supplies

BMI = body mass index = weight (kg) / height squared (m)2
 < 20 underweight
 20 - 25 normal weight
 25 - 30 overweight – 1st degree (light) obesity
 30 - 40 2nd degree (significant) obesity
 > 40 3rd degree (malignant) obesity
Intake control
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Two areas in the hypothalamus:
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Centre of fullness (ventromedial nucleus) = if it is activated, no
need of food intake
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Centre of hunger (lateral nucleus) = if it is activated, need of
food intake
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Hormones:
Leptin is protein hormone that plays a key role in regulating
energy intake. Leptin is released by fat cells in amounts body
fat stores. Thus, circulating leptin levels give the brain
(hypothalamic centers) information about energy storage for the
purposes of regulating appetite and metabolism.

Orexin (hypocretin) is hormone that was suggested to be
primarily involved in the stimulation of food intake. Now it is
know that it is also responsible for sleep (its dysregulation
causes narcolepsy).
Disorders = obesity or cachexia
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Factors affecting food intake
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Activation or inhibition of hypothalamic food intake centers
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Information from the stomach = few hours after emptying stomach
spontaneous “hungry” contractions appear
Surrounding temperature = cold stimulates feeling of hunger, warm
inhibits it
Body temperature = after meal body temperature increases and
decreases appetite and induce feeling of fullness.
Glycostatic cells in the hypothalamus = register level of glycemia.
Decrease of glycemia stimulates centre of hunger, increase of
glycemia inhibits it.
Other regions of the CNS = cortex – conditioned reflex (perception
of aroma, form), tradition, time schedule
Total energy situation of organism = decrease of supplies and
increase of appetite after sport, hard work
Obesity
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Obesity is a condition where the natural energy reserve,
stored in the fatty tissue is increased to a point where it is
thought to be a significant risk factor for certain health
conditions as well as increased mortality.
Excessive body weight has been shown to correlate with
various important diseases, particularly cardiovascular
disease, Diabetes mellitus type 2, sleep apnea and
osteoarthritis.
Not only percentage of fat in the body but also the WHR =
waist hip ratio is important
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Abdominal (men’s) type of obesity (like apple) = high risk for most of the
diseases
 WHR men > 0.95
 WHR women > 0.85
Gynoid (women’s) type of obesity (like pear) = lower risk
BMI > 30
Anorexia
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Anorexia nervosa is an eating disorder characterized by
voluntary starvation involving psychological and
sociological components.
Symptoms:
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Refusal to maintain body weight at or above a minimally
normal weight for age and height (less than 85% of that
expected, BMI < 17.5).
Intense fear of gaining weight or becoming fat.
Amenorrhea (the absence of at least three consecutive
menstrual cycles).
Treatment: hospitalization, psychotherapy, collaboration
with family
Bulimia
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Bulimia nervosa is an eating disorder. It is a
psychological condition in which the subject
engages in recurrent binge eating followed by the
following activities in order to compensate for the
food intake and prevent weight gain:
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vomiting
inappropriate use of laxatives, enemas, diuretics or
other medication
excessive exercising
fasting
Water intake control
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Centers in the hypothalamus near to the
paraventricular nucleus
 Centre of thirst
Regulation: osmoreceptors = activated based on
the osmotic changes in the body
 hypertonic environment induces feeling of
thirst
hypotonic the opposite
Role of ADH, Aldosterone and others
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Monitoring of food intake
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Quantitative point of view = energy from food intake
should be the same as energy consumption
Qualitative point of view = ratio of food components has
to correspond to demand of the body (with respect of the
age, work, climatic conditions, etc.)
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Carbohydrates - 50 – 80 %
Lipids - 20-30 %
Proteins - 10-15 %
During starvation 70-80% of glucose needed for the
brain, the rest erythrocytes. Muscles use fatty acids.
Carbohydrates
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Function: important storage and transport form of
energy.
Low carbohydrates intake: Very low carbohydrate
diets can slow down brain and neural function (the
nervous system especially relies on glucose).
High carbohydrates intake: Diabetes mellitus
Lipids
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Function:
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Low lipid intake:
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Cell membrane structure
Energy storage
Important for some vitamins (absorption and metabolism of vitamins soluble
in fat; butter important source of vitamin A)
Essential lipids: Arachidonic acid, Linoleic acid and Linolenic acid (mostly
in vegetal oils = include important fosfolipids)
missing essential lipids
hypovitaminosis
High lipid intake: Hyperlipidemia – risk of cardiovascular diseases

Normal: cholesterol < 5.2 mmol/l
triacylglycerols < 1.7 mmol/l
LDL < 3.9 mm/l
HDL > 0.9 mmol/l
Proteins (1)
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Function: proteins are involved in functions controling
almost all the molecular processes of the body (enzymes,
hormones, structural proteins, antibodies etc.).
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Essential aminoacids: leucine, isoleucine, valine, methionine,
phenylalanine, lysine, threonine, tryptophan.
Semiessential aminoacis: histidine, arginine (during growing),
tyrosine (during kidney failure – not formation from
phenylalanine).
Nitrogen balance: protein intake and excretion
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Positive nitrogen balance: Higher intake (kidney load)
Optimal protein intake: 0.8 g / kg (in children and pregnant
women 1.3-2.0 g/kg)
Proteins (2)
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Low protein intake:
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Marasmus = insufficient amount of food with balanced
composition
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Kwashiorkor = type of childhood malnutrition caused by
inadequate protein intake in the presence of fairly good total
calorie intake.
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Extremely decreased lipid storage in the body, muscle atrophy
("autocannibalism") and body weight less than 80% of normal
Low oncotic pressure – ascites
Secundar hypoproteinemia: Insufficient carbohydrate intake
(gluconeogenesis), cirrhosis (albumin insufficiency), kidney
failure (lost of proteins), malabsorption (absorption disorder)
High protein intake: (more than 1.5 – 2.0 g/kg/day)

Kidney overload, increased blood pressure (salty sausages)
Vitamins (1)
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The word vitamine was coined by the Polish
biochemist Casimir Funk in 1912.
Vita in Latin is life and the -amine suffix is for
amine; at the time it was thought that all vitamins
were amines.
A vitamin is an organic molecule required by a
living organism in small amounts for proper health.
An organism deprived of all sources of a particular
vitamin will eventually suffer from disease
symptoms specific to that vitamin – Avitaminosis.
Vitamins (2)
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Avitaminosis is any disease caused by chronic or longterm vitamin deficiency or caused by a defect in metabolic
conversion.
Hypervitaminosis is the syndrome of symptoms caused by
over-retention (mostly of fat-soluble vitamins) in the body,
which can lead to toxic symptoms.
In humans, there are thirteen vitamins, divided into two
groups, the four fat soluble vitamins (A, D, E and K) and
the nine water soluble vitamins (eight B vitamins and
vitamin C).
Water soluble vitamins
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Vitamin C - Ascorbic acid
Vitamins B
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Vitamin B-1 (Thiamine)
Vitamin B-2, also Vitamin G (Riboflavin)
Vitamin B-3, also Vitamin P or Vitamin PP (Niacin)
Vitamin B-5 (Pantothenic acid)
Vitamin B-6 (Pyridoxine and Pyridoxamine)
Vitamin B-7, also Vitamin H and Vitamin B-w (Biotin)
Vitamin B-9, also Vitamin M and Vitamin B-c (Folic acid) important for pregnancies
Vitamin B-12 (Cyanocobalamin)
Fat soluble vitamins
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Vitamin A – Retinol
Vitamin D
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Vitamin D2 - Ergocalciferol
Vitamin D3 - Cholecalciferol
Vitamin E - Tocopherol
Vitamin K
Attention!
Risk of hypervitaminosis!
Vitamin A
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Chemical Name: Retinol
Solubility: Fat
Daily dose: 620μg
Source:
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Plants: green vegetable, darkly colored fruits
Animals: milk, liver, eggs, fish oil
Function: Antioxidant. Production of rhodopsin (visual pigment),
essential for the correct functioning of epithelial cells, glycoprotein
synthesis, involved in maintaining healthy lymphocytes and T-cells,
needed for normal haemopoiesis, production of human growth
hormone.
Deficiency disease:Night blindness, blindness by making the cornea
very dry and damaging the retina, immunodeficiency, abnormalities
in iron metabolism.
Hypervitaminosis: 7.5 mg or higher dose. High levels of carotene
are not toxic.
Vitamin A toxicity
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Livers of certain animals, especially those adapted
to polar environments (polar bears) contain toxic
dose of vitamin A.
Xavier Mertz, a Swiss scientist who died in January
1913 on an Antarctic expedition that had lost its
food supplies and fell to eating its sled dogs.
Vitamin A supply:
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Osteoporosis
Lung cancer
Teratological effects
Vitamin E
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Chemical Name: Tocopherol
Solubility: Fat
Daily dose: 12 mg
Source:
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Function: Antioxidant. Vitamin E is often used in skin creams and lotions because
it is believed to play a role in encouraging skin healing and reducing scarring after
injuries such as burns.
Deficiency disease:
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Plants: Vegetable oils, nuts, green leafy vegetables
Animals: milk, eggs, meat
Persons who cannot absorb dietary fat, has been found in premature, very low birth
weight infants
Individuals who cannot absorb fat may require a vitamin E supplement because some
dietary fat is needed for the absorption of vitamin E from the gastrointestinal tract.
Muscle dystrophy, sterility.
Hypervitaminosis: 4,000 mg or higher dose, not clear yet. May have anticoagulant
effect and increase the risk of bleeding problems?
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Vitamin D
Chemical Name: D3 = cholecalciferol
Solubility: Fat
Daily dose: 2 µg for all Vitamin D
Source: fish oil, fish liver
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Function: The most active form of the vitamin is calcitriol, a potent
steroid hormone. Calcitriol is synthesized from calcidiol in the
kidneys to perform its endocrine function of maintaining the calcium
metabolism.
Deficiency disease:
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It is made in the skin when cholesterol reacts with ultraviolet light in the skin.
Rickets (kids) = bone pain, slowed growth, dental problems, muscle loss and
increased risk of fractures.
Osteomalacia (adults) = lack of calcium results in bone fragility
In certain parts of the world, particularly at higher latitudes, total vitamin D
input is usually not sufficient, especially in the winter (milk with D2 or D3)
Hypervitaminosis: 1,250 mg or higher dose, hypercalcemia,
atherosclerosis
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Vitamin K
Chemical Name: Naphthoquinone
Solubility: Fat
Daily dose: 75 µg
Source: vegetables
Function:
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Deficiency disease: Bleeding.
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Involved in the carboxylation of certain glutamate residues in proteins to form
gamma-carboxyglutamate residues.
blood coagulation (prothrombin-factor II, factors VII, IX, X)
bone metabolism
vascular biology
Normally it is produced by bacteria in the intestines, and dietary deficiency is
extremely rare unless the intestines are heavily damaged.
Vitamin K-deficiency may occur by disturbed intestinal uptake (such as
would occur in a bile duct obstruction), by therapeutic or accidental intake of
vitamin K-antagonists
Hypervitaminosis: GIT disorders, increased coagulation - anemia
Vitamin C (1)
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Chemical Name: Ascorbic acid
Solubility: Water
Daily dose: 75 mg
Source:
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Plants: Citrus fruits (orange, lemon, grapefruit, lime), tomatoes, potatoes,
cabbage, wild roses
Function:
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Participation in hydroxylation, vitamin C is needed for the production of
collagen in the connective tissue.
Strong antioxidant.
Required for synthesis of dopamine, noradrenaline and adrenaline in the
nervous system or in the adrenal glands.
Vitamin C is also needed to synthesize carnitine, important in the transfer of
energy to the cell mitochondria.
Vitamin C (2)
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Deficiency disease: Scurvy
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loose teeth
superficial bleeding
fragility of blood vessels
poor healing
compromised immunity
mild anemia
Hypervitaminosis: Not known
Vitamin B-1
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Chemical Name: Thiamine or thiamin
Solubility: Water
Daily dose: 1 mg
Source:
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Plants: yeast, pulse, cereal
Animals: liver
Function: Cofactor in decarboxylation processes.
Deficiency disease: Beri-beri, GIT disorders (anorexia, nausea,
vomiting), tiredness, weakness, PNS disorders (paresthesia,
coordination disorders), psychic disorders (depression, irritation,
disorders in memory and coordination).
Hypervitaminosis: Not known.
Beri-Beri
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In people whose staple diet consists mainly of polished
white rice, which contains little or no thiamine.
Disease of nervous system
Symptoms
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weight loss, emotional disturbances, impaired sensory
perception (Wernicke's encephalopathy), weakness and pain
in the limbs, and periods of irregular heartbeat.
Swelling of bodily tissues (edema) is common.
may cause heart failure and death.
Vitamin B-2 (1)
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Chemical Name: Riboflavin or Vitamin G
Solubility: Water
Daily dose: 1.1 mg
Source:
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Plants: leafy green vegetables, yeast, almonds, soybeans
Animals: milk, cheese, liver
Function:
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supports energy production by aiding in the metabolising of fats,
carbohydrates, and proteins.
required for red blood cell formation and respiration, antibody production,
and for regulating human growth and reproduction.
essential for healthy skin, nails, hair growth and general good health,
including regulating thyroid activity.
helps in the prevention or treatment of many types of eye disorders, including
some cases of cataracts.
Vitamin B-2 (2)
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Deficiency disease:
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leasion of GIT mucous (glossitis, stomatitis, corner of
mouth, cheilitis)
skin diseases (dermatitis)
Hypervitaminosis: Not known
Vitamin B-3
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Chemical Name: Niacin or Vitamin P, resp.PP or nicotinic acid
Solubility: Water
Daily dose: 12mg
Source:
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Function: its derivatives such as NADH play essential role in energy
metabolism in cell and DNA repair.
Deficiency disease:
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Plants: yeast, corn
Animals: eggs, liver
mild deficiency slows down the metabolism, which in turn decreases cold
tolerance and is a potential contributing factor towards obesity.
Pelagra: caused by dietary lack of niacin and protein, especially the essential
amino acid tryptophan. Symptoms: red skin lesions, diarrhea, dermatitis,
weakness, mental confusion, and eventually dementia.
Hypervitaminosis: 2,500 mg or higher dose. Symptoms: High
blood pressure, low blood cholesterol levels
Vitamin B-5
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Chemical Name: Pantothenic acid
Solubility: Water
Daily dose: 10 mg
Source:
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Plants: yeast, whole grain cereals
Animals: eggs, liver
Function:Part of CoA. Necessary for breaking down
carbohydrates, proteins, and fats.
Deficiency disease: allergies (e.g. stuffed or runny nose),
adrenal insuffiency (Addison's disease) and rheumatoid
arthritis. Dermatitis, enteritis, alopecia.
Hypervitaminosis: Not known
Vitamin B-6
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Chemical Name: Pyridoxine
Solubility: Water
Daily dose: 1.1 mg
Source:
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Plants: yeast, whole grain cereals
Animals: liver
Function: Balancing of Na+ and K+, promoting red blood cell
production. It is linked to cancer immunity and helps fight the
formation of homocysteine. Helps children with learning difficulties,
may prevent dandruff, eczema, and psoriasis. Helps balance
hormonal changes in women.
Deficiency disease: Anemia, nerve damage, seizures, skin problems,
and sores in the mouth. Pyroluria.
Hypervitaminosis: 400 mg or higher dose. Causes temporary
deadening of certain nerves (proprioceptory nerves) and feeling of
disembodiment common with the loss of proprioception.
Vitamin B-7
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Chemical Name: Biotin or Vitamin H
Solubility: Water
Daily dose: 30 µg
Source:
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Plants: yeast
Animals: seafood, liver, kidneys, milk, eggs
Function: Important in the catalysis of essential metabolic reactions
to synthesize fatty acids, in gluconeogenesis, and to metabolize
leucine.
Deficiency disease: Hair loss which progresses in loss of eye lashes
and eye brows. Dry skin, seborrheic dermatitis, fungal infections.
Changes in mental status, depression, generalized muscular pains
(myalgias), hyperesthesias and paresthesias
Hypervitaminosis: Not known
Vitamin B-9
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Chemical Name: Folic acid or Vitamin M
Solubility: Water
Daily dose: 320 μg
Source: Green vegetable, fruits, cereals
Function: Production and maintenance of new cells (especially
during infancy and pregnancy), necessary for replicating DNA and
synthesizing RNA. Both adults and children need folate to make
normal red blood cells and prevent anemia.
Deficiency disease:
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Diarrhea, loss of appetite, weight loss, weakness, sore tongue, headaches,
heart palpitations, irritability, and behavioral disorders.
Hypervitaminosis: 1,000 µg or higher dose. Low risk - may shade
the B12 deficiency.
Vitamin B-12
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Chemical Name: Cyanocobalamin
Solubility: Water
Daily dose: 2 µg
Source:
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Function: coenzyme in metabolism of aminoacids, stimulates
erytropoesis
Deficiency disease:
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Plants: breakfast cereals (only source for vegetarians)
Animals: Liver, shellfish, eggs, milk
Megaloblastic anemia = inadequate intake of B12
Pernicious anemia = autoimmune anemia (antibodies are directed against
intrinsic factor). Intrinsic factor is required for vitamin B12 absorption, so
impaired absorption of vitamin B12 can result. The term pernicious anemia is
sometimes used more loosely to include non-autoimmune causes of vitamin
B12 deficiency.
Malabsorption in terminal ileum, demyelination of periferal nerves.
Hypervitaminosis: Now known