VITAMINS

Vitamin

Vitamins are organic substances that constitute a range of many different types of organic molecule which are essential to the proper functioning of the human organism. They are formerly known as ‘accessory food factors.

For example- vitamin A, vitamin B2 etc.
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. A compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on the circumstances and the particular organism. Ascorbic acid functions as vitamin C for some animals but not others, and vitamins D and K are required in the human diet only in certain circumstances.

Vitamins have diverse biochemical functions, including function as hormones (e.g. vitamin D), antioxidants (e.g. vitamin E), and mediators of cell signaling and regulators of cell and tissue growth and differentiation (e.g. vitamin A). The largest number of vitamins (e.g. B complex vitamins) function as precursors for enzyme cofactor bio-molecules (coenzymes), that help act as catalysts and substrates in metabolism. When acting as part of a catalyst, vitamins are bound to enzymes and are called prosthetic groups. For example, biotin is part of enzymes involved in making fatty acids. Vitamins also act as coenzymes to carry chemical groups between enzymes. For example, folic acid carries various forms of carbon group – methyl, formyl and methylene - in the cell. Although these roles in assisting enzyme reactions are vitamins' best-known function, the other vitamin functions are equally important.

Classification:
According to the solubility they can be classified in two brought types –
1) Fat Soluble Vitamins
2) Water Soluble Vitamins

Fat soluble vitamins are further of four types-
a) Vitamin A (A1, A2). Example- Retinol
b) Vitamin D (D2-D6). Example- Cholecaloferol
c) Vitamin E. Example- α-Tocopherol
d) Vitamin K (K1, K2). Example- Phytonadione

Water soluble vitamins are dominated by the vitamin B complex. It also included vitamin C, biotin-
a) Vitamin B (B1-B3,B5, B6, B9, B12). Example- Thiamine, Riboflavine, Miacin etc.
b) Vitamin C. Example- Ascorbic acid
c) Vitamin H. Example- Biotin