Vitamin D is more than just one vitamin. It’s a family of nutrients that shares similarities in chemical structure. In your diet, the most commonly found members are vitamin D2 and D3.

4 Diagram showing biosynthesis of active form of vitamin D - Calcitriol - via the kidneys and the liver - schematic molecular structure chemical illustration. Image Credit: Bass stock/Shutterstock ...

vitamin D, was unambiguously identified in the 1930s, thanks to the work of researchers studying the chemical structures of members of the cholesterol family.