A half century ago, doctors from Europe and North America who spent time in central Africa were struck by the absence of multiple sclerosis there. Indeed, the farther from the equator people lived, the more prevalent multiple sclerosis (MS) seemed to become thus arose the “latitude hypothesis” of MS, suggesting that a lack of direct sunshine somehow contributed to the nerve-damaging immune malfunction underlying the disease.
A recent study from southern California now lends new credence to the sunshine theory of MS protection. They studied 179 sets of identical twins in which one had MS and the other didn’t. Estimating these individuals’ childhood sun exposures, the scientists found that the twins with MS on average had gotten less sun. This study is further supported by a 2003 report from Australia that associated greater sun exposure and a history of sunburns in childhood with reduced risk of MS. One additional study found that people with MS were only half as likely as the general population to develop skin cancer.
“There’s clear evidence from multiple publications to suggest this is something that’s ral,” say Avery August of Pennsylvania State University, an immunologist not part of these studies. “There’s a genetic component to MS but also an environmental component,” he says. Science News July 28th 2007