Vitamin D, also known as the “sunshine vitamin,” is an essential vitamin that plays many important roles in the proper functioning of the body. Though classified as a vitamin, vitamin D is actually a key regulatory hormone for calcium and bone metabolism. Adequate vitamin D status is essential for ensuring normal calcium absorption and maintenance of healthy plasma calcium levels. Besides bone support, vitamin D has many other roles in the body, including modulation of cell growth, neuromuscular function, immune function and inflammatory support.