In addition to what’s already been mentioned, there actually are numbers assigned to other families of vitamins. For example, there’s vitamin D2 (ergocalciferol) and D3 (cholecalciferol), as well as K1 (phylloquinone) and K2 (menaquinone). However, in those cases, they’re very closely related chemically and serve similar biological functions, whereas the B vitamins are very different.
Latest Answers