Vitamins may be defined as potent organic compounds which is found in food in variable and minute quantity, and must be supplied to the animal organisms from external source , so that specific physiological functions, vital to life , may go on normally.
The general characteristics of the vitamins are given belows :-
1. Distribution. The vitamins are widely distributed in nature_both in the animal and vegetable kingdoms. All vitamins are manufactured in plants. The animals can manufacture a few only but can store all to some extent. Almost all common articles of food contain more than one vitamin.
2. Daily requirement. Vitamins can perform their work in very low concentration. Hence , the total daily requirement is usually very small. The daily need of any vitamin for any individual is not a fixed quantity. It varies according to the rate of metabolism.
3. Store. Vitamins can be stored in the body to some extent, for example, the fat -soluble vitamins are stored in the liver and the subcutaneous tissue, vitamin C in adrenal cortex,etc.
4. Vitamins are not destroyed in the digestive process and are, therefore, absorbed as such . Hence , all vitamins are effective when administered orally.
5. Solubility. Some of them are soluble in water and others in fats and fat – solvents.
6. Artificial synthesis. Most of the vitamins have been artificially synthesized.
Vitamins & there function :-
Vitamins are Classifed into :-
i) Fat Soluble Vitamins
ii) Water Souble Vitamins
Fat Soluble Vitamins :- Vitamins which are soluble in fat & insoluble in water,are termed as fatsoluble vitamins. These include :-
Water Souble Vitamins :- Vitamins which are souble in water.
Vitamin B Complex :- Vit. B, Vit. B2
Sources/Distribution . Vitamin A is present only in lipid of animal sources and carotenoid, in vegetable ones .
Animal Sources :- Cod liver oil, Milk, Butter, Egg, Fishes are also rich sources.
Vegetable Sources :- Carrots, Spinach, Green leaves, Tomatoes
Functions :- 1) Essential for growth. 2) It is a component of rhodopsin, hence essential for night vision. 3) Prevents infection ( secondary to normal epithelial tissues). 4) It plays some part in protein synthesis. 5) Help in keeping normal fertility. 6) Prevents the condition known as urolithiasis where urinary calculi in the form of calcium phosphate is present.