<P> A vitamin is an organic molecule ( or related set of molecules ) which is an essential micronutrient -- that is , a substance which an organism needs in small quantities for the proper functioning of its metabolism but can not synthesize , either at all or in sufficient quantities , and therefore must obtain through its diet . The term vitamin does not include the three other essential nutrients : essential mineral ( nutrient ) s , essential fatty acids , and essential amino acids . Some substances can be synthesized by a certain organism , but not by another : that substance is not a vitamin in the first instance , but it is in the second . Most vitamins are not single molecules , but groups of related molecules called vitamers . Vitamins are classified by their biological / chemical activity , not their structure . The thirteen vitamins required by human metabolism are : vitamin A ( retinols and carotenoids ) , vitamin B ( thiamine ) , vitamin B ( riboflavin ) , vitamin B ( niacin ) , vitamin B ( pantothenic acid ) , vitamin B ( pyridoxine ) , vitamin B ( biotin ) , vitamin B ( folic acid or folate ) , vitamin B ( cobalamins ) , vitamin C ( ascorbic acid ) , vitamin D ( calciferols ) , vitamin E ( tocopherols and tocotrienols ) , and vitamin K ( quinones ) . </P>
<P> A vitamin is an organic molecule ( or related set of molecules ) which is an essential micronutrient -- that is , a substance which an organism needs in small quantities for the proper functioning of its metabolism but can not synthesize , either at all or in sufficient quantities , and therefore must obtain through its diet . The term vitamin does not include the three other essential nutrients : essential mineral ( nutrient ) s , essential fatty acids , and essential amino acids . Some substances can be synthesized by a certain organism , but not by another : that substance is not a vitamin in the first instance , but it is in the second . Most vitamins are not single molecules , but groups of related molecules called vitamers . Vitamins are classified by their biological / chemical activity , not their structure . The thirteen vitamins required by human metabolism are : vitamin A ( retinols and carotenoids ) , vitamin B ( thiamine ) , vitamin B ( riboflavin ) , vitamin B ( niacin ) , vitamin B ( pantothenic acid ) , vitamin B ( pyridoxine ) , vitamin B ( biotin ) , vitamin B ( folic acid or folate ) , vitamin B ( cobalamins ) , vitamin C ( ascorbic acid ) , vitamin D ( calciferols ) , vitamin E ( tocopherols and tocotrienols ) , and vitamin K ( quinones ) . </P>
what is the scientific name of vitamin b3
what is the scientific name of vitamin b3
niacin
niacin