Daily exposure to sun and being thin as teens delayed the onset of multiple sclerosis (MS) than who limited their sun exposure and are overweight, revealed a new study. The study was published in the Journal Neurology.
"The factors that lead to developing MS are complex and we are still working to understand them all, but several studies have shown that vitamin D and sun exposure may have a protective effect on developing the disease. This study suggests that sun exposure during the teenage years may even affect the age at onset of the disease," said Dr. Julie Hejgaard Laursen, of Copenhagen University Hospital in Denmark.
Researchers analyzed 1,161 people with MS in Denmark. They were categorized into two groups based on their exposure to sunlight during their teenage. Consumption of Vitamin D supplements and fatty fish during their teenage was also taken into account.
It was found that the onset of MS in people who were exposed to sun was 1.9 years later than those who were not exposed to sun every day. They developed MS at an average age of 32.9 compared to 31 for those who were not in the sun every day. 88% of participants were exposed to sun daily.
People who were obese at 20 years of age developed the disease at an average of 1.6 years earlier than those who were average weight and 3.1 years earlier than those who were underweight. 18% of participants were overweight and they developed the disease at an average age of 31.2.
"It appears that both UVB rays from sunlight and vitamin D could be associated with a delayed onset of MS. However, it's possible that other outdoor factors play a role, and these still have to be identified. The relationship between weight and MS might be explained by a vitamin D deficiency, but there's not enough direct evidence to establish this yet," said Laursen.
"A limitation of the study is the risk of recall bias because participants were asked to remember their sun, eating and supplement habits from years before. In particular, someone with a long history of MS and onset of the disease at an early age, may wrongly recall a poor sun exposure. Additionally, only Danish patients were included into the study, so there should be caution when extending the results to different ethnic groups living in different geographic locations," she added.