The February 8, 2011 issue of the journal Neurology® reports a protective effect for high vitamin D levels and sun exposure against the risk of developing multiple sclerosis (MS). Multiple sclerosis is an autoimmune disorder characterized by progressive damage to the nerves’ myelin sheathes. Symptoms include weakness, numbness, dizziness and other disturbances that can come and go for decades. The disease is diagnosed after an initial demyelinating event during which symptoms are experienced. Research has found a greater incidence of the disease in higher latitudes that are exposed to less sunlight, which reduces the body’s production of vitamin D.
Robyn Lucas, PhD, of Australian National University in Canberra and colleagues compared 216 men and women aged 18 to 59 who had experienced their first event to 395 individuals who had no symptoms of the disease. The subjects were matched for age, gender and region of residence.
Dr Lucas’ team discovered that the risk of having a first demyelinating event, which was estimated to be between two to nine cases per 100,000 people per year, was reduced by 30 percent for every 1,000 kilojoule increase in ultraviolet light exposure. Additionally, those with the most sun damage to their skin were 60 percent less likely to have a first event compared to participants with the least damage. Having a high level of serum vitamin D also proved to be protective.
“Previous studies have found similar results, but this is the first study to look at people who have just had the first symptoms of MS and haven’t even been diagnosed with the disease yet,” Dr Lucas remarked. “Other studies have looked at people who already have MS—then it’s hard to know whether having the disease led them to change their habits in the sun or in their diet.”
“Added together, the differences in sun exposure, vitamin D levels and skin type accounted for a 32-percent increase in a diagnosed first event from the low to the high latitude regions of Australia,” she noted.
Despite the study’s finding concerning the protective benefit of sun exposure, Dr Lucas cautioned that sunbathing and tanning beds have risks that outweigh their benefits, and sun exposure has not been shown to help people who already have multiple sclerosis. “Further research should evaluate both sun exposure and vitamin D for the prevention of MS,” she said.
From LEF.org http://www.lef.org/newsletter/2011/0208_Higher-Vitamin-D-Levels-Equal-Lower-Risk-of-Multiple-Sclerosis.htm?source=eNewsLetter2011Wk6-1&key=Article&l=0#article