definition of vitamins
Vitamins are conventionally divided into the fat-soluble group A, D, E and K, and the water-soluble group, vitamin C (ascorbic acid) and the B vitamins-B 1 (thiamine), B 2 (riboflavine, riboflavin), nicotinic acid, B6 (pyridoxine), pantothenic acid, biotin, folic acid and B12.