For many years, vitamin D was boring—even to doctors. Because it was considered good for bones and not much else, multitaskers like vitamin A, B vitamins and vitamin E hogged all the press. But recent studies have thrust this long-neglected nutrient into the spotlight… Studies link low blood levels of vitamin D to type 1 diabetes, multiple sclerosis, tuberculosis, colon cancer and even the flu. High levels of the vitamin may help fight HIV infection…Levels higher than the RDA offer older adults protection against fractures, through strengthening muscles as well as bone…We have only three ways of boosting our blood levels of the nutrient: increasing sun exposure, increasing our intake of vitamin D-rich foods or taking vitamin D supplements. Because of the risk of skin cancer, getting a lot more sun exposure is not a healthy way to raise blood levels of vitamin D. The only foods with high levels of vitamin D are fatty fish and certain kinds of mushrooms. The other main dietary source is fortified foods: dairy foods (milk has 100 IU per cup), some brands of orange juice and fortified breakfast cereals.

That’s why there’s growing agreement among experts that a daily vitamin D supplement makes good sense. Among nutritionists working on vitamin D, there is general agreement that the current recommended intake of 400 IU per day (600 for those over the age of 70) is too low, and should be re-evaluated. Most believe that 1,000 IU per day would be a reasonable dose for a typical adult in the United States, and I agree. Certain people might benefit from taking even more, such as those who avoid the sun or live in northern regions. The elderly and African-Americans are especially vulnerable to vitamin D deficiency, and I think supplementation…should be routine for these groups.

—Meir Stampfer, MD, DR, PH, MSNBC.com, 12/5/06