WASHINGTON, Jan 12: Vitamin D - which the body makes when exposed to sunlight - may help prevent multiple sclerosis and rheumatoid arthritis, two studies suggest.

The findings may help explain why the two autoimmune diseases are more common in northern climes, where sunlight is often scarce, the researchers said.

In a study released on Monday for the latest issue of Neurology, the researchers found women who take multivitamins containing vitamin D are 40 percent less likely to develop multiple sclerosis than women who do not take supplements.

"Because the number of cases of MS increases the farther you get from the equator, one hypothesis has been that sunlight exposure and high levels of vitamin D may reduce the risk of MS," said Kassandra Munger of the Harvard School of Public Health in Boston, who led the study.

"These results need to be confirmed with additional research, but it's exciting to think that something as simple as taking a multivitamin could reduce your risk of developing MS."

Multiple sclerosis is a crippling disease caused when the immune system mistakenly damages the myelin, the protective fatty sheath around nerves.-Reuters