"There have been a number of very intriguing population findings, but we still don't know if supplementation will affect the risk of cardiovascular disease," Wang said. "A clinical trial would be needed to see if supplementation could avert risk. We know that the things to prevent vitamin D deficiency include sunlight and proper diet."
But Dr. Denise Teves, an endocrinologist who is an assistant professor of medicine at the Medical College of Wisconsin, said a case could be made for vitamin D supplements for some people.
"I recommend supplements for some patients who come to me with metabolic bone disease," she said. "Most have insufficient vitamin D."
Existing guidelines might fall short of what is needed for some people, Teves said.
"The current guidelines do call for 400 units a day," she said. "But in the last two or three years, many endocrinologists have been recommending at least 800 units a day. I have seen many students in Wisconsin in the wintertime with low vitamin D levels."
It's best to consult a doctor about taking large amounts of a vitamin D supplement, Teves said.
A fact sheet on vitamin D is available from the U.S. Office of Dietary Supplements.
SOURCES: Michal Melamed, M.D., assistant professor, medicine and epidemiology and population health, Albert Einstein College of Medicine, New York City; Thomas J. Wang, M.D., assistant professor, medicine, Harvard Medical School and Massachusetts General Hospital, Boston; Denise Teves, assistant professor, medicine, Medical College of Wisconsin, Milwaukee; April 16, 2008, presentation, American Heart Association Arteriosclerosis, Thr
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