Vitamin D Metabolism

Vitamin D plays an important role in bone metabolism. Vitamin D is a group of biologically inactive, fat-soluble prohormones that exist in two major forms: ergocalciferol (vitamin D2) produced by plants in response to ultraviolet irradiation and cholecalciferol (vitamin D3) derived from animal tissues or 7-dehydrocholesterol in human skin by the action of ultraviolet rays present in sunlight. Vitamin D, which is biologically inactive, needs two-step hydroxylation for activation. All of these steps are of crucial for Vitamin D to show its effect properly. In this section, we will present vitamin D synthesis and its action steps in detail.