You may think you're getting enough vitamin D (either through sunlight exposure or supplementation), but how do you really know? It's all about the serum levels; you can in take a lot of vitamin D but not assimilate it. Vitamin D inadequacy or deficiency increases your risk of chronic and debilitating disease, leads to reduced longevity and substantially elevates your cancer risk. Most Americans are vitamin D deficient. Find out the minimum levels you need to avoid disease – and how you can test for them.

41 -min. DVD