Most potent form of vitamin D is:

Vitamin D Ergocalciferol (Vitamin D2) =Formed from ergosterol and cholecalciferol (vitamin D3) and are known as Pro-vitamins =Vitamins D2and D3 are not biologically active. 25-OH- cholecalciferol =Major storage and circulating form of vitamin D 1, 25 dihydroxycholecalciferol =aka Calcitriol =most biologically active form of vitamin D Vitamin D encompasses a group of sterols, which have a hormone-like function. Bioactive vitamin D or calcitriol is a steroid hormone that has long been known for its impoant role in regulating body levels of calcium and phosphorus, and in mineralization of bone.