Vitamin D

Vitamin D, calciferol, is a fat-soluble vitamin. It is made in your body after it is exposed to ultraviolet rays from the sun. It is also found in certain foods. Vitamin D serves many functions and comes in many forms. Some forms are relatively inactive in the body, but others play crucial roles.

Major Functions:

Fortified foods are the major dietary sources of vitamin D because of its scarcity in foods naturally.

Main Sources:

Source:
New York State Department of Health
http://www.health.state.ny.us/diseases/conditions/osteoporosis/vitd.htm