Vitamin D plays an important role in several bodily processes including building and maintaining strong bones.
The 3 main sources are sun exposure, diet and supplementation.
The skin, through solar radiation, provides 90% of the body's vitamin D needs. Low levels can be caused by lack of sun exposure or type of diet.
It is possible to obtain sufficient amounts of vitamin D with 15 minutes in the sun for lighter skin and 30 minutes to 1 hour/day for dark or brown skin. The darker the skin, the harder it is to produce vitamin D.