Known as the sunshine vitamin, Vitamin D is a key regulatory hormone for calcium and bone formation. Adequate vitamin D intake is important for ensuring normal calcium absorption and maintaining proper calcium plasma levels. People living in Canada and the northern states have to rely more on foods and supplements for adequate vitamin D status, whereas people living in southern regions of the U.S. can derive significant amounts of vitamin D from sunlight-dependent synthesis in the skin. It is not always practical to get your vitamin D from sunshine, and quite difficult to get adequate amounts from your diet so for many people, a vitamin D supplement is a practical way to ensure adequate levels of this important protector are always available in your bloodstream.