MS Risk and Racial Groups

Because dark-skinned people do not make vitamin D through the skin as easily as light-skinned people, separate analyses were conducted among whites, blacks, and Hispanics. UV rays from the sun allow vitamin D to be made in the skin.

The investigation revealed that among whites, people with the highest circulating vitamin D levels had the lowest MS risk. Compared with whites with the lowest levels, those with the highest were found to have a 62% lower risk for developing the disease.

The strongest association was seen among the youngest study participants.

Vitamin D and the Immune System

Ascherio says the findings add to the mounting evidence supporting a role for vitamin D in regulating the immune system and suppressing autoimmune reactions.

Earlier research from the Harvard team suggested a protective role for vitamin D against rheumatoid arthritisrheumatoid arthritis, another autoimmune disease.

Other researchers have reported that vitamin D deficiency may increase the risk of a wide range of medical maladies, including heart diseaseheart disease, diabetesdiabetes, unexplained muscle and joint pain, and certain cancers.

William F. Finn, MD, who has been studying vitamin D for many years, agrees that large, randomized trials are needed to confirm the vitamin’s role in protecting against MS or any of these diseases.

But he says it is not too soon to recommend that people take vitamin D in supplement form.

Most multivitamins contain 400 IU of vitamin D, which has been thought to be a sufficient daily dosage. But Finn argues that most people need between 800 and 1,000 IU a day, especially in the winter when they are getting less of the vitamin from sun exposure.

He says blacks and other dark-skinned people may need even more than that.

Finn is a professor of medicine at the University of North Carolina at Chapel Hill.

"It is important to discuss this with your doctor, but I believe that most people could benefit from getting more vitamin D," he says. "Vitamin D deficiency or insufficiency is a very common problem in the United States."

SOURCES: Munger, K.L. The Journal of the American Medical Association, Dec. 20, 2006; vol 296: pp. 2832-2838. Alberto Ascherio, MD, DrPH, associate professor of nutrition and epidemiology, department of nutrition, Harvard School of Public Health, Boston. William F. Finn, MD, professor of medicine, University of North Carolina, Chapel Hill.