Fri Aug 8, 5:26 PM ET
By Karla Gale
SOURCE: British Medical Journal, August 9, 2003
While sitting in the sun may carry health dangers, new research suggests it could lower the chances of getting multiple sclerosis (MS). The strongest benefit seems to occur with sun exposure during childhood.
This is the first evidence of an association between sun exposure and MS in studies involving people with or without MS, Dr. Terry Dwyer, from University of Tasmania in Hobart, Australia, told Reuters Health.
He stressed, however, that "this finding needs to be confirmed by other studies before recommendations should be given to people about how they might prevent MS through sun exposure."
More than one million people worldwide suffer from MS, which causes muscle weakness, paralysis, slurred speech and vision problems. MS is thought to occur when a person's own body attacks myelin, a fatty sheath that surrounds nerves and helps them to transmit signals fast and efficiently.
Dwyer and colleagues interviewed residents of Tasmania, including 132 patients diagnosed with MS and 272 healthy people. They asked all subjects to estimate the number of hours they were exposed to sun during weekends and on holidays.
Those with the least sun exposure were most likely to have MS, the authors found. After accounting for smoking and the amount of melanin pigment in skin, they found that people who spent at least 2 to 3 hours per day in the sun were about a third as likely as others to have MS.
Sun-damaged skin was also linked to a lower risk of MS, the report published in the British Medical Journal indicates.
"This finding is consistent with observations that MS prevalence is lower in countries with higher levels of sunlight," Dwyer told Reuters Health.
It appears that "winter sun exposure might be more important in prevention than summer sun exposure, and that only moderate levels of exposure might be necessary," he added. So, people who are told to avoid the sun during the summer because of the well-known skin cancer risk should probably heed this advice.
If sunlight does, in fact, prevent MS, it could be that the ultraviolet
radiation in sunlight prevents the body from attacking its own myelin,
Copyright © 2003, Reuters Limited