Biology of Disease

Vitamins

Vitamins are organic substances that the body cannot synthesize or can make
only from chemically closely related compounds. They are needed in the diet
but only in relatively small amounts (Table 10.3).

Vitamins may be classified as water soluble, such as the B group and vitamin C
(Figure 10.9) and fat soluble, such as the vitamins A, D, E and K. Some of the B
vitamins and, in general, each fat soluble vitamin comprise a group of closely
related compounds called vitamers. In such cases, the name of the vitamin is
used as a collective descriptor. Vitamins have specific biochemical roles and
are essential for normal metabolism, growth and good health.

DIET AND NUTRITION

CZhhVg6]bZY!BVjgZZc9Vlhdc!8]g^hHb^i]:YLddY ')*

Figure 10.9 Computer generated models of the

water soluble vitamins (A) B 2 and (B) C. Oxygen

atoms are shown in red, carbon in black, nitrogen

in gray and hydrogen are colorless.

Vitamin or related

compounds

Recommended

intake / mg day–1

Sources

Vitamin B 1

Thiamin

1.0 in males

0.8 in females

yeast, eggs, milk, cheese and cereals

Vitamin B 2

Riboflavin

1.3 in males

1.1 in females

liver, milk, cereals, mushrooms and eggs

Niacin or nicotinic acid

Nicotinamide

17 in males

13 in females

meat, fish, pulses, cereals and synthesized

endogenously from tryptophan

Vitamin B 5

Pantothenic acid

3–7 is normally

provided in diet and

appears more than

adequate

meats, offal, eggs, green vegetables,

whole grains

Vitamin B 6

Pyridoxine

Pyridoxal

Pyridoxamine

1.4 in males

1.2 in female

vegetables, fruit, cereals, eggs, milk and nuts

Vitamin H

Biotin

0.01–0.2 in adults eggs, pulses, liver, yeast, milk, dried fruit and

can be synthesized by intestinal bacteria in

the GIT

Folic acid 0.2 in adults

0.4 in pregnancy

liver, spinach, cabbage, peas, bananas and

oranges

Vitamin B 12

Cobalamin

0.0015 in adults liver, egg and milk

Vitamin C

Ascorbic acid

40 in adults green vegetables and citrus fruits

Vitamin A Retinol

Retinal

Acarotene

0.7 in males

0.6 in females

liver, fish oils, eggs, cheese and can be

synthesized from carotene in the diet

Vitamin D

Cholecalciferol

Ergocalciferol

0.01 in pregnancy liver and dairy products and endogenous

synthesis in the skin if there is adequate

exposure to sunlight.

Vitamin E

Tocopherol

Tocotrienols

4 in males

3 in females

vegetable oils, nuts and wheat germ

Vitamin K

Phylloquinone,

Menaquinones

0.001 in adults leafy vegetables, cheese or synthesized by

colon bacteria

Table 10.3Recommended intakes of vitamins and some of their sources