Vitamin D might help protect people from developing multiple sclerosis, an incurable disease of the central nervous system, a study reports today.

If the link between vitamin D and MS pans out, people might be able to ward off the potentially crippling disease by taking vitamin D supplements, says lead researcher Alberto Ascherio of the Harvard School of Public Health.

“The idea that we could prevent many cases of MS with vitamin D is extremely appealing,” Ascherio says.

But the findings don’t prove the case for vitamin D just yet. A large, tightly controlled study is needed before public health officials can recommend high doses, which have risks of their own, such as kidney stones, Ascherio says.

Ascherio and his colleagues studied U.S. Army and Navy personnel who had blood samples stored in the Department of Defense Serum Repository. The team zeroed in on 257 men and women who had at least two serum samples that had been collected before they developed MS, a disease that causes vision loss, difficulty walking and other symptoms. They compared the MS patients with a control group of more than 500 healthy people in the Army or Navy.

Among whites, those with the highest blood levels of vitamin D had a 62% reduced risk of developing the disease. The protection was the strongest for people who were younger than 20 — a finding that suggests that to be effective, a protective agent might need to kick in very early in life, Ascherio says.

The team found no association between blood levels of vitamin D and MS in blacks or Hispanics, possibly because the researchers didn’t have very many black or Hispanic participants in the study.

MS afflicts 400,000 people in the USA and often strikes people in the prime of life — in their late 20s or 30s. But Ascherio and others say the disease might get started in the brain in the teen years. MS is thought to be the result of an autoimmune attack on a protective sheath (myelin) that covers the axons of nerve cells. When the immune system attacks myelin, nerve cells can’t transmit messages effectively and people develop symptoms, says Nicholas LaRocca, an associate vice president at the National MS Society in New York.

The study appears in today’s Journal of the American Medical Association.

The findings fit with previous studies in which vitamin D prevented an MS-like disease in mice, LaRocca says. But there’s no proof yet that vitamin D will protect humans from this disease, he says.

People need adequate levels of vitamin D to build strong bones so experts including Ascherio recommend eating foods rich in it, such as salmon or low-fat dairy products. And Ascherio says it can’t hurt to get very brief exposure to the sun — enough to get pink but not burned. The skin makes vitamin D after exposure to sunlight, he says. (c) Copyright 2005 USA TODAY, a division of Gannett Co. Inc.