Water-soluble organic compounds with loosely similar properties, distribution in natural sources, and physiological functions.
Most are coenzyme s, and all appear essential to the metabolic processes of all animal life. They include thiamin (B 1 ), riboflavin (B 2 ), niacin , vitamin B 6 , pantothenic acid , folic acid , biotin , and vitamin B 12 (cobalamin); some authorities also include choline , carnitine, lipoic acid, inositol, and para -aminobenzoic acid. Vitamin B 6 is needed for metabolism of amino acids and prevention of skin and nerve disorders. Vitamin B 12 prevents pernicious anemia and is involved in nucleic-acid synthesis, fat metabolism, and conversion of carbohydrate to fat. The B complex vitamins are particularly abundant in cereal grains, meats, nuts, and some fruits and vegetables.