Andrew Lessman's VITAMIN D3-1000 contains 1,000 IU of Vitamin D3 in its most active and beneficial form - Cholecalciferol. Overwhelming scientific research has validated Vitamin D3 as the single most important vitamin to supplement. We also combine our Vitamin D with Calcium and Magnesium, because of their shared role in bone health. In fact, Calcium cannot be absorbed without adequate Vitamin D, thus making Vitamin D just as important as Calcium for bone health. That should be enough to encourage everyone to consume extra Vitamin D, but it is Vitamin D's other exciting benefits that are making headlines and have experts urgently seeking to raise the recommended intake of Vitamin D. The body can only produce small amounts of Vitamin D when exposed to sunlight (UV radiation), but reduced sun exposure and increased use of sunscreens, as well as the normal aging process, makes our own internal production of Vitamin D extremely limited and unreliable. Moreover, Vitamin D is not readily available in food - only present in small amounts in some fish and eggs. As a result, for over 30 years, ProCaps has always provided extra Vitamin D in all of our multivitamins and Calcium products. An enormous amount of recent research has confirmed the wisdom and necessity of consuming extra Vitamin D, and with our Vitamin D3-1000 you receive the benefits of the most active form of Vitamin D, plus a bonus of essential Calcium and Magnesium. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.