While it seems we are frequently warned of the supposed skin-related hazards of sunshine, there is abundant evidence that sunlight exposure is associated with general benefits for health. For instance, sunlight helps protect against low mood and depression, as well as several forms of cancer.
There is also evidence that it might help prevent multiple sclerosis, a degenerative neurological condition, which can lead to a range of symptoms, including abnormal sensations, visual problems, and disability.
Last week, a study published in the journal Neurology assessed the relationship between sunlight exposure in childhood and risk of multiple sclerosis (MS) in identical twins. In each pair of twins, one of them had a diagnosis of MS. Identical twins were chosen in this study, as they are genetically identical. That means that the fact that one twin had MS and the other didn't must have been due to environmental factors.
Each of the nine sun-exposure related activities during childhood were assessed in each pair of twins. Increased sun exposure was strongly related to a reduced risk of MS. The degree of apparent protection ranged from 43 to 75 percent, depending on the activity. For instance, the twin who spent more time sunbathing was found to be at about a 60 percent reduced risk of MS compared to the other twin.
Sunlight exposure on the skin is known to increase the manufacture of vitamin D. This vitamin is known to have effects on the immune system, which could have relevance to MS, as the condition is essentially caused by immune activity in the nervous system. There is some thought that sunlight might act directly on the immune system, and that this might be a factor too.
While it's obviously possible to overdo sunlight exposure, this research adds yet more evidence to the existing evidence linking sunlight exposure to broad benefits for health.
References:
Islam T, et al. Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins. Neurology 2007; 69:381-388.
Dr. John Briffa is a London-based doctor, author, and health writer with an interest in nutrition and natural medicine.
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