The Sunshine Vitamin
Vitamin D is otherwise known as “sunshine vitamin” as it can be synthesized from sunlight by our body.

Chemistry
The term vitamin D refers to a family of compounds that are derived from cholesterol. There are two major forms of vitamin D: vitamin D2, found in plants and better known as ergocalciferol (or calciferol). And vitamin D3, found in animal tissues and often referred to as cholecalciferol.

Among these vitamin D2 or calciferol and vitamin D3 or cholecalciferol are biologically important. Ergosterol and 7dehydrocholesterol act as provitamin of vitamin D.



When ergosterol of vegetable origin is exposed to ultraviolet light calciferol is formed.



Vitamin D3 is formed by the action of ultraviolet rays of sunlight on 7dehydrocholesterol. Which is present in our skin. If the body is kept in “Purdah” or covered for a prolong time cholecalciferol is not produced by the body.

source:https://bnethub.com/vitamin-d-sources-deficiency-overall-benefits/