Vitamins

A or Retinol (Fat soluble).

Source; green vegetables, dairy produce, liver, fish oils.

Needed for; the manufacture of rhodopsin - a pigment needed by the rod cells of the eye for night vision. Also for the maintenance of the skin and tissues.

Deficiency; night blindness and possible total blindness.

B complex including Thiamin, Riboflavin, Nicotinic acid, Pantothenic acid, Biotin, Folic acid, B₆, Pyroxidine, B₁₂ (cyanocobalamin), Lipoic acid. (Water soluble - Thiamin)

Source; green vegetables, dairy produce, cereal, grains, eggs, liver, meat, nuts, potatoes, fish.

Needed for; the manufacture of red blood cells, for the enzyme activity and for amino acid production. Also for maintaining the fatty sheath (myelin) around nerves.

Deficiency; Beri beri (B₁ deficiency) anaemia and deterioration of the nervous system
(B₁₂ deficiency)

C (Ascorbic acid) (Water soluble).

Source; citrus fruit, green vegetables.

Needed for; maintaining cell walls and connective tissue. Aiding the absorption of iron by the body.

Deficiency; scurvy - affects skin, blood vessels and tendons

D (Fat soluble)

Source; red meat, fish oils, eggs, dairy produce (also exposure of skin to the Sun)

Needed for; control of calcium levels required for bone growth and repair

Deficiency; Rickets in children - deformation of the bones. Osteomalacia in adults - softening of the bones.
Was very common amongst Vegetarians/Vegans emigrating from hot, sunny climates to ones similar to that of Britain.

E (Fat soluble)

Source; cereal, grains, eggs, green vegetables

Needed for; maintenance of cell membranes

Deficiency; unusual as common in diet

K (Fat soluble)

Source; leafy green vegetables, especially spinach, liver

Needed for; clotting of the blood

Deficiency; rare as it is also manufactured by bacteria in the gut

Vitamins; Vitamins are chemical substances present naturally in most foods and, in synthetic form, in vitamin pills. Both forms are equally nutritious since the vitamins in each case are chemically identical. The body needs only tiny quatities of them - ranging from about 30 mg ( 30 thousanths of a gram ) a day of vitamin C, for instance, down to 1 microgram ( one millionth of a gram ) of vitamin B₁₂. They play no direct part on producing body tissues or energy, but they are essential for the body to function efficiently, just as oil is essential for the running of a car ( automobile ).
  Vitamin deficiencies can lead to illness and, in extreme cases, death. The killer diseases scurvy and beri-beri are caused by deficiencies of the vitamin C and B₁ respectively. Deficiency of vitamin A can cause night blindness, and rickets ( a childhood disease of the bones ) is due to a deficiency of vitamin D. Anyone who eats a variety of foods, however, is unlikely to run into problems.