Many studies have shown that sun exposure and vitamin D levels have a protective effect against multiple sclerosis (MS).
A study published in Neurology (online, 7 October 2015)
, which included 1,161 Danish patients, found that sun exposure in the summer during teenage years influences the timing of the onset of MS. The 88% of patients who said they had spent time in the sun every day as a teenager developed MS at an average age of 32.9 compared with 31.0 (P=0.02) among patients who spent less time outdoors.
Study author Julie Laursen, from Copenhagen University Hospital, says the results support the protective role of sun exposure in MS. This could be an outcome of increased vitamin D levels, but could also be explained by independent effects of sun exposure on the development of a healthy immune system, she suggests.
 Laursen JH, SÃ¸ndergaard HB, SÃ¸rensen PS et al. Association between age at onset of multiple sclerosis and vitamin D level–related factors. Neurology 2015. doi:10.1212/WNL.0000000000002075