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 calciumplasma levels. It is estimated that at least 40% of the U.S. population is Vitamin D deficient, therefore supplementing the diet with extra Vitamin D can be essential for optimal health. Vitamin D has also been recognized as being important for normal, healthy cell growth and function, normal, healthy insulin secretion, and healthy immune function.