Douglas Laboratories Vitamin D 5000 IU contains 5000 IU of vitamin D3 per tablet. 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. Numerous scientists now feel that supplementation with vitamin D at levels greater than previously thought necessary is critical to helping maintain healthy bone remodeling as we age. Vitamin D 5000 IU may be a useful dietary supplement for those individuals wishing to support bone health or whose requirements for vitamin D cannot be met by lower potency products.