Vitamins : Vitamins are organic compounds which are required in small, quantities in our diet for the maintenance of normal health. Their deficiency causes specific diseases. Plants can synthesise almost all vitamins. Vitamins are designated by alphabets A, B, C, D, E, K. Some of them are further named as subgroups e.g. `B_1 , B_2, B_6, B_12` etc. Excess of vitamins is also harmful.
Vitamins are classified into two groups depending upon their solubility in water or fat.
1) Fat soluble vitamins : These are soluble in fat and oils but insoluble in water. Vitamins A, D, E and Ķ are fat soluble vitamins.
2) Water soluble vitamins : B group vitamins and vitamin C are soluble in water.
Some vitamins, their sources and deficiency diseases :
Vitamin A : (Retinol) is found in fish oils, carrots, butter and milk. its deficiency causes xerophthalmia (hardening of cornea of eye) and night blindness.
Vitamin `B_1` (Thiamine) : Occurs in yeast, milk, cereals, green vegetables etc. Its deficiency causes beri beri.
Vitamin `B_2` (Riboflavin) : Occurs in yeast, vegetables, milk, egg white etc. Its deficiency causes cheilosis, digestive disorders and burning sensation of the skin.
Vitamin `B_^` (Pyridoxin) : It is found in yeast, milk, cereals and grams. Its deficiency causes convulsions.
Vitamin `B_(12)` (Cyanocobalamine) : It is available in meat, fish, egg and curd. Its deficiency causes pernicious anaemia.
Vitamin K : it is found in green leafy vegetables. Its deficiency leads to increased blood clotting time.
Vitamin D (Calciferol) : Exposure to sun light, fish and egg yolk serve as sources of vitamin D. Its deficiency causes rickets.
