So say researchers who were expected to present the findings Friday at the World Congress on Treatment and Research in Multiple Sclerosis, in Montreal.

The idea fits nicely with previous research indicating that multiple sclerosis is more common the farther away you get from the equator, in other words, in areas where there is less sunlight.

Vitamin D synthesis is triggered when ultraviolet rays from the sun hit the skin. In addition, studies have also linked vitamin D with immune system function.

"In MS, the immune system is misregulated, and we do know that there's a susceptibility in the genes we inherit from our parents. We know that something triggers the disease," explained Patricia O'Looney, vice president of biomedical research at the National Multiple Sclerosis Society. "We know from epidemiological studies that there's a higher prevalence of MS the farther away you live from the equator and, more recently, we've learned that vitamin D does regulate the immune system."

"This is an interesting study of how environmental triggers and the immune system can be involved with MS, provided that one has these susceptibility genes," she added.

"Many studies have given us a good link between vitamin D status and immune function in MS," added study author Heather E. Hanwell, a doctoral candidate in nutritional sciences at the University of Toronto. "We wanted to see whether vitamin D status was lower in children who had their first demyelinating event and were subsequently diagnosed with MS."

A first demyelinating event is essentially an attack of symptoms that could indicate trouble with the central nervous system. One quarter of children who have such an attack go on to be diagnosed with MS.

The researchers measured levels of a vitamin D biomarker in children who had had a first event.

"The biomarker of vitamin D status was significantly lower in children diagnosed with MS to date," Hanwell said. "Children diagnosed with MS had lower vitamin D levels than those not diagnosed. Another way of looking at it, as vitamin D status increased, children had a lower risk of being diagnosed."

At this point, however, Hanwell believes the findings have more research than clinical implications.

"This type of work provides impetus for further research in this area, although, for a doctor, it would be important to look at vitamin D status in patients, particularly because 75 percent of our overall study group had vitamin D levels below what we considered to be optimal."

A second study also being presented at the World Congress found that the incidence of first demyelinating events increased by 9.2 percent for each higher degree of latitude up the eastern coast of Australia. The study was partially funded by the National Multiple Sclerosis Society, in the United States.