More than 1,000 medical studies have been conducted on Vitamin D and they have found that Vitamin D has a wide ranging impact on our health, from reducing our risk of heart disease, colon cancer, breast cancer to lowering our risk of diabetes. About 1/2 of all Americans do not get enough Vitamin D. Vitamin D comes from direct sunlight, fish, fortified dairy and cereal products and supplements. The recommended guideline is 400 I.U. daily ALTHOUGH more and more experts believe we should be getting 1000 I.U. of D daily. You can boost your Vitamin D levels by increasing your sun exposure to 10-15 minutes a day, eating fish and Vitamin D fortified foods and taking supplements.