Vitamins are nonenergy 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.
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.
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