Sun exposure and multiple sclerosis

Higher exposure to sunlight during childhood and adolescence may protect and lower the chances of getting multiple sclerosis. The strongest benefit seemed to occur with sun exposure during childhood. More than one million people worldwide suffer from multiple sclerosis, which causes muscle weakness, paralysis, slurred speech and vision problems. Multiple sclerosis is thought to occur when a person's own immune system attacks myelin, which is a fatty sheath surrounding nerves and helping them to transmit neural signals fast and efficiently. Researchers from the University of Tasmania in Hobart, Australia, interviewed residents of Tasmania, including 132 patients diagnosed with multiple sclerosis and 272 healthy people. They asked all subjects to estimate the number of hours they were exposed to sun during weekends and on holidays. It was found that those with the least sun exposure were most likely to have multiple sclerosis. After accounting for smoking and the amount of melanin pigment in skin, the researchers 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 multiple sclerosis. Sun-damaged skin was also linked to a lower risk of multiple sclerosis. It was believed that winter sun exposure might be more important in prevention than summer sun exposure, and that only moderate levels of exposure might be necessary. If sunlight does, in fact, prevent multiple sclerosis, it could be that the ultraviolet radiation in sunlight prevents the body from attacking its own myelin. Although this is the first evidence of an association between sun exposure and multiple sclerosis in studies involving people with or without multiple sclerosis, it needs to be confirmed by other studies before recommendations should be given to people about how they might prevent multiple sclerosis through sun exposure.