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  • Created on: 02-05-13 20:36

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MICRONUTRIENTS- needed in small amounts yet essential for good health (30
needed by body)
Vitamins are not synthesised (produced) by body- obtained from food (otherwise
deficiencies occur)
Amount of vitamins/minerals in food vary with:
Growing conditions
Storage conditions
Processing- enriched or fortified
Most people meet requirements with a varied diet (eat well plate) however to reach
optimum levels it may be necessary to take supplements (although advised to eat vit.
rich foods instead of sup.)
Some people have higher than normal requirements due to:
Pregnancy- higher requirements of folic acid (prevent NTD- spine bifida)
Older people- higher requirement for Vitamin D (As they may be housebound)
Vegans- Require B12 (Don't eat animal products)
Iron required by adolescent girls
Supplements are also useful for those with: poor appetites/illnesses/inadequate intake of
Harm in Supplements:
Users of Supplements need to be careful not to take any overdoses of the tablets-
especially fat soluble Vitamins. This is because the body stores fat soluble vitamins
(Vitamins A, D, E and K) therefore excessive amounts will be stored and can
cause harm.
Pregnant women shouldn't take Vitamin A supplements unless prescribed- can
cause defects in child
Also supplements can encourage poor eating habits and can be expensive
People who may require supplements:
People on medication Elderly people
People with disease Vegetarians
People with poor appetites

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Why take Vitamins?
Not synthesized by body
Essential in diet
Vitamins are not chemically similar to each other
Each vitamin has a specific function (or set of functions)
Fat Soluble Vitamins: A,D,E&K Water Soluble Vitamins: C&B group
Dissolve in fats and oils (not water) Dissolves in water (not fat)
Stored by body, in liver Not stored in body (excess excreted)
Excess amounts lead to Measured in milligrams
Measure in micrograms
How much do we need?
The body requires different amounts of each vitamin because…read more

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Food preparation
Several biochemical mechanisms can either enhance or diminish nutrient absorption,
Iron, Copper and manganese hinder absorption of Vitamin A,D and E
Vitamin B12 is assisted by adequate folate
Cereals and pulses contain iron and phytate and phytate inhibits iron from being
The amount you absorb will depend on your needs, on your ability to absorb nutrients
and on amount available to you. Good diet management can affect bio-availability e.g.…read more

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Fat Soluble Vitamins:
Vitamin A
Retinol: animal foods such as milk, cheese, egg yolk, oily fish (herring)
Beta carotene: in plant foods such as: carrots, mangoes, melon. (darker the
green the more beta carotene it contains)
NB Vitamin A is added to margarine to make it nutritionally equivalent to butter
Required to make substance called RHODPSIN (visual purple).…read more

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Factors affecting absorption: Low protein or fat intake will adversely affect metabolism
and absorption. Acute infections lower Vitamin A concentrations in the blood.
Effects of cooking and storage: Vitamin A is usually not affected by cooking methods.
During storage retinol in fatty foods may be lost due to oxidation (however this is
prevented through use of antioxidants, by refrigeration and by exclusion of lights e.g.…read more

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Sunlight: Vitamin D is formed in skin on exposure to sunlight. Amount varies
according to latitude, time spent in the sun and degree of pigmentation of skin
Requirements: Normal sunlight meets requirements.…read more

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Most foods contain at least a small amount of Vitamin E (wheat germ, vegetable oils,
nuts, egg yolk and pulses (especially soya beans) are particularly good sources) Fruit and
veg. contain little
Natural antioxidant in cell membranes.
The antioxidant is also used commercially (e.g. in vegetable oils) as it helps to
reduce rancidity by preventing oxidation of unsaturated fatty acids.…read more

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Processing and refining flour
Cooking in fats- 70%-90% loss
Boiling- 30% loss
Canning 80% loss
Vitamin K
Properties: -heat stable ­affected by irradiation
Obtained in large amounts from leafy green vegetables (broccoli and spinach) also
from eggs, milk, wheat bran and fish oils
Can be synthesised by bacterial action in the intestine
There is a small store of Vitamin K in the liver
Requirements: Normal diet provides adequate amounts.
Deficiency: Rarely seen in the first few months of life.…read more

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Requirements: Since thiamin is needed for the oxidation of the glucose the amount
required by the body is related to the amount of carbohydrate in the
diet. Requirement for women is less due to less body mass resulting
in a low energy requirement.
Deficiency: Retarded growth
Fatigue, depression and irritability
Beriberi: nervous disease associated with loss of appetite, leading
to reduced food intake and enlargement of heart may occur (over
time).…read more

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Excess: Body excretes it
Factors affecting Absorbed in the intestine
absorption and
Effects of cooking Slightly soluble in water
and storing(in this Less stable in alkaline conditions
case sunlight, as Overall loss during cooking is small
well): Riboflavin is sensitive to light (e.g.…read more


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