Vitamins

VITAMINS

Vitamins are non-energy producing organic compounds, essential for normal human metabolism, that must be supplied in small quantities in the diet. This definition excludes the inorganic essential trace minerals and essential amino acids and fatty acids which are required in much larger quantities. Other substances needed for proper growth of microorganisms or cells in culture are called ‘growth factors’. The different chemical forms and precursors of a vitamin can be called its Vitamers (analogy—isomers).

The importance of vitamins as drugs is primarily in the prevention and treatment of deficiency diseases. Some vitamins do have other empirical uses in pharmacological doses. Vitamin deficiencies occur due to inadequate intake, mal-absorption, increased tissue needs, increased excretion, certain genetic abnormalities and drugvitamin interactions.

Vitamins, as a class, are over-promoted, over-prescribed and overused. Myths like ‘they energise the body’, ‘any physical illness is accompanied by vitamin deficiency’, ‘vitamin intake in normal diet is precariously marginal’, ‘they are harmless’ are rampant.

Vitamins are traditionally divided into two groups:

Fatsoluble (A, D, E, K):

These (except vit K) are stored in the body for prolonged periods and are liable to cause cumulative toxicity after regular ingestion of large amounts. Some interact with specific cellular receptors analogous to hormones.

Watersoluble (B complex, C):

These are meagerly stored: excess is excreted with little chance of toxicity. They act as cofactors for specific enzymes of intermediary metabolism.

Vitamin D (Ch. No. 24), K (Ch. No. 44), folic acid and B12 (Ch. No. 43) have already been considered.