U.S. researchers have suggested that the ultraviolet portion of sunlight may play a bigger role than vitamin D in controlling multiple sclerosis.

MS is much more common in higher latitudes than in the tropics and researchers have wondered if the high levels of vitamin D engendered by sunlight could explain this unusual pattern of prevalence, said Hector DeLuca and Bryan Becklund of the University of Wisconsin-Madison.

DeLuca says in a statement, "It's true that large doses of the active form of vitamin D can block the disease in the animal model. That causes an unacceptably high level of calcium in the blood, but we know that people at the equator don't have this high blood calcium, even though they have a low incidence of MS."

Using mice that are genetically susceptible to MS-like disease, the researchers triggered the disease by injecting a protein from nerve fibers. The researchers then exposed the mice to moderate levels of ultraviolet radiation for a week.

It is further said by the study that ultraviolet exposure did not change how many mice got the MS-like disease, but it did reduce the symptoms of MS, especially in the animals that were treated every other day.

Although the ultraviolet exposure did increase the level of vitamin D, that effect, by itself, could not explain the reduced MS symptoms, the researchers have found. (With Inputs from Agencies)