People who spend more time in the sun, and those with higher vitamin D levels, may be less likely to develop multiple sclerosis (MS), according to new Australian research.
MS is a chronic disease of the brain and spinal cord and has long baffled researchers, who continue to search for its cause and cure.
Associate Professor Robyn Lucas from the College of Medicine, Biology and Environment at the Australian National University, who co-ordinated the research said that many people who experience preliminary symptoms of the sort that occur in MS - known as a 'first event' - go on to develop the disease. His Ausimmune Study found that the risk of having a first event was lower in people with higher sun exposure - over the whole of their lives as well as in the months preceding the event, compared with unaffected people of the same age and sex and living in the same region of Australia.
"People with the highest levels of vitamin D were also less likely to have a diagnosed first event than people with the lowest levels," she said.
The study is the first to look at sun exposure and vitamin D status in people who had experienced a first event with the type of symptoms found in MS.
"Previous studies have looked at people who already have MS," said Dr Lucas. "This has made it difficult to know whether having the disease led them to change their habits in the sun or their diet. That is, it has not been possible to work out if low sun exposure or vitamin D cause the disease or were caused by having the disease."
Associate Professor Lucas said that the study showed, for the first time in a human population, that the effects of sun exposure and vitamin D act independently of each other, with each having a beneficial effect in decreasing the risk of a first event.
"Further research should evaluate both sun exposure and vitamin D for the prevention of MS," she said.
The findings have been published in the February 8, 2011, issue of Neurology, the medical journal of the American Academy of Neurology.