n. any of several organic chemical substances not synthesized by an animal and required in small quantities for normal metabolism, present in and obtained from the natural foods eaten by the animal. Human vitamins are also produced synthetically, and taken in pure form or in mixtures, as dietary supplements. Deficiencies of specific vitamins lead to certain specific disorders, such as scurvy, caused by an insufficiency of vitamin C (ascorbic acid). Most vitamins act as coenzymes or precursors to coenzymes, and are not consumed for energy production or incorporated into structural units of the cell. [ PJC ]

n. any of several related fat-soluble vitamins (such as retinol) essential for normal vision; it also prevents night blindness or inflammation or dryness of the eyes.
Syn. -- antiophthalmic factor, axerophthol. [ WordNet 1.5 ]

n. retinol (C20H30O), one of the substances also called vitamin A. It is also called more specifically vitamin A alcohol. It is a required factor for human nutrition. The USP unit of activity is equal to 0.30 micrograms of retinol.
Syn. -- retinol. [ WordNet 1.5 +PJC ]

n. dehydroretinol (C20H28O), one of the substances also called vitamin A. It has about 40% of the bioactivity of vitamin A1.
Syn. -- dehydroretinol. [ WordNet 1.5 +PJC ]

n. a group of water-soluble vitamins originally thought to be a single vitamin but now separated into several B vitamins.
Syn. -- B-complex vitamin, B complex, vitamin B complex, B vitamin. [ WordNet 1.5 ]

n. a B vitamin (C12H17N4OS)Cl that prevents beriberi and maintains appetite and growth. Same as thiamine.
Syn. -- thiamin, aneurin, antiberiberi factor. [ WordNet 1.5 ]

n. a B vitamin that is used to treat pernicious anemia.
Syn. -- cobalamin, cyanocobalamin. [ WordNet 1.5 ]

n. a B vitamin that prevents skin lesions and weight loss.
Syn. -- vitamin G, riboflavin, lactoflavin, ovoflavin, hepatoflavin. [ WordNet 1.5 ]

n. See nicotinamide.
Syn. -- nicotinamide. [ PJC ]

n. See nicotinic acid.
Syn. -- nicotinic acid. [ PJC ]