Although a new national study says that an abundance of vitamin D seems to help prevent multiple sclerosis, an Everett neurologist says people shouldn’t rush out to buy the vitamin.

“It’s not like taking vitamin D will prevent MS,” said Dr. Nancy Lellelid, who works at The Everett Clinic and treats about 200 MS patients.

In Snohomish County, about 1,100 people have MS. In Western Washington, about 8,000 people have the disease.

“MS is such an intricate disease with many different causes and factors that can lead to it,” Lellelid said. “Obviously, it’s not just as simple as having lack of vitamin D exposure.”

The MS study, which appears in today’s Journal of the American Medical Association, involved more than 7 million people. It is said to offer some of the strongest evidence yet of the power of the “sunshine vitamin” against the disease.

The research found that white members of the U.S. military with the highest blood levels of vitamin D were 62 percent less likely to develop multiple sclerosis than people with low levels.

There was no such connection in blacks or Hispanics, possibly because there were so few in the group studied. Also, the body makes vitamin D from sunlight, and the pigmented skin of blacks and other dark-skinned ethnic groups doesn’t absorb sunlight as easily as pale skin.

The study was funded in part by the National Multiple Sclerosis Society.

Lellelid said that studies on possible links between vitamin D and MS have been known for a while.

Because of this, some patients have asked if they should go to tanning booths, since the body can process vitamin D from sunlight.

“I said no,” Lellelid said. She said heat can increase the symptoms of MS, such as numbness, tingling and vision problems. “You feel like a limp noodle from weakness,” she said.

Low-fat diets seem to have the best promise of doing something to help the disease, she said.

The new research echoes findings in smaller studies that examined why the nerve-damaging disease historically has been more common in people who live in regions farther from the equator, where there is less intense year-round sunlight.

“This is the first large prospective study where blood levels are measured in young adults and compared with their future risk. It’s definitely different and much stronger evidence,” said Dr. Alberto Ascherio, the senior author and an associate professor of nutrition at Harvard’s School of Public Health.

“If confirmed, this finding suggests that many cases of MS could be prevented by increasing vitamin D levels,” Ascherio said.

Still, he said the findings don’t prove that a lack of vitamin D can cause MS, so it’s too preliminary to recommend that people take vitamin D pills to avoid the disease.

Washington has a high incidence of MS, affecting about 180 of every 100,000 people, said Erin Poznanski, program director for the National Multiple Sclerosis Society’s Greater Washington Chapter in Seattle.

The links between vitamin D and MS are discussed in the current issue of the organization’s magazine, Inside MS, she said.

No one knows exactly what causes the disease, she said, although researchers are trying to find out.

“Certainly one of those factors is they think there may be a genetic predisposition,” she said.

But scientists are still trying to determine whether something in the environment or even a virus may be the trigger, she said.

Vitamin D is found in fortified milk and oily fish, but it’s hard to get enough just from diet. Sunlight is the biggest source of vitamin D, which is needed for strong bones. Other studies have linked high levels of vitamin D in the blood to lower risks of a variety of cancers.

The MS researchers worked with the Army and the Navy in analyzing blood samples of military personnel stored by the Department of Defense.

Military databases showed that 257 service men and women were diagnosed with MS between 1992 and 2004. The increased MS risk was especially strong in people who were younger than 20 when they entered the study. The researchers said that finding suggests that vitamin D exposure before adulthood could be particularly important.

Using blood samples to measure vitamin D levels “tends to nail it down in a much more reliable way” than studies that have relied on people’s memories of vitamin D exposure, said Dr. Nicholas LaRocca of the National Multiple Sclerosis Society.

MS is among the most common nerve disorders affecting young adults, mostly females. About 350,000 people in the United States and 2 million worldwide have MS, a chronic autoimmune disease in which the body attacks the fatty insulation that surrounds nerve fibers.

Ascherio said there’s some evidence that its incidence is increasing in sunny regions, including the South and the West, possibly because people are avoiding the sun or using sunscreen to protect against skin cancer.

Some doctors think those practices also have contributed to vitamin D deficiencies in adolescents and young adults.

“There’s no question that vitamin D deficiency is an epidemic in the United States,” said Dr. William Finn, a vitamin D expert at the University of North Carolina at Chapel Hill. The MS study “is just one more reason to pay attention to it.”

The Associated Press contributed to this report.

In search of Vitamin D

Sunlight is the biggest source of vitamin D, which is needed for strong bones. Vitamin D also is found in fortified milk and oily fish, but it’s hard to get enough of the vitamin just from your diet.