MS is a complex disease which results from the interplay between nature (genetic factors) and nurture (environmental conditions). Vitamin D deficiency is a risk factor for developing MS. Exposure to sunlight (ultraviolet radiation) can help the body to make active vitamin D.
People who live in higher geographical latitudes may receive lower levels of sunlight, and therefore have lower vitamin D levels which could explain why there is a higher incidence of MS in countries with higher latitudes.
In this multi-centre study, led by University of Tasmania in Australia, the authors looked at the records of more than 20,000 people with MS from 21 countries in the MSBase registry. They found that people with MS who came from countries with higher latitudes had an earlier onset of MS (approximately 2 years earlier).
The authors supported these results by looking at sunshine exposure (ultraviolet B radiation) in those countries. The researchers found that those living in the lowest category of ambient ultraviolet radiation had nearly a 2-year earlier age at onset than those in the highest.
These results underline the effects of environment, and exposure to sunlight in changing the risk of developing MS.
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