The role of Vitamin D is helping to maintain bone density and strength is clear. It is required for the process of moving calcium through the intestinal wall into the bloodstream.
Even though the human body can manufacture Vitamin D under ideal circumstances, there is strong evidence that much of the American population suffers from a deficiency of the nutrient. This means that supplementation may be important.
Vitamin D has emerged as the "star supplement". It plays a key role in the proper absorption of calcium for strong bones and teeth and has been shown to support colon, breast, prostate, ovarian, heart and colorectal health. It also supports a health immune system in adults.
Not all forms of Vitamin D work equally well in humans. Vitamin D3 (cholecalciferol) should be used in preference to Vitamin D2 (ergocalciferol), researchers said in a study published in the October, 2006, issue of the American Journal of Clinical Nutrition. Vitamin D2 has been predominately used in North America for vitamin D supplements, but Houghton, LA and Vieth, R, authors of the study from Acadia University said that an increasing body of evidence suggests that vitamin D3 has a greater bio-efficacy. In this study the authors also claimed vitamin D2 is inferior to vitamin D3 because vitamin D2 in synthetic form is less stable and has more impurities, which could potentially lead to a high risk of toxicity.
Reference: Houghton LA, Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement, Am J Clin Nutr 2006;84:694-7 (PubMed) abstract