vitamin /vī″təmin/ [L, vita + amine, ammonia] , an organic compound essential in small quantities for normal physiological and metabolic functioning of the body. With few exceptions, vitamins cannot be synthesized by the body and must be obtained from the diet or dietary supplements. No one food contains all the vitamins. Vitamin deficiency diseases produce specific symptoms, usually alleviated by the administration of the appropriate vitamin. Vitamins are classified according to their fat or water solubility, their physiological effects, or their chemical structures. They are designated by alphabetic letters and chemical or other specific names. The fat-soluble vitamins are A, D, E, and K. The B complex and C vitamins are water soluble. See also avitaminosis, hypervitaminosis, oleovitamin, provitamin.
