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Dictionary definition: vitamin
- Article from:
- A Dictionary of Biology
Copyright© A Dictionary of Biology 2004, originally published by Oxford University Press 2004. (Hide copyright information)
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vitamin
One of a number of organic compounds required by living organisms in relatively small amounts to maintain normal health. There are some 14 generally recognized major vitamins: the water-soluble
vitamin B complex
(containing 9) and
vitamin C
and the fat-soluble
vitamin A
,
vitamin D
,
vitamin E
, and
vitamin K
. Most B vitamins and vitamin C occur in plants, animals, and microorganisms; they function typically as
coenzymes
. Vitamins A, D, E, and K occur only in animals, especially vertebrates, and perform a variety of metabolic roles. Animals are unable to manufacture many vitamins themselves and must have adequate amounts in the diet. Foods may contain vitamin precursors (called
...