UV-B Exposure, MS Risk Linked

High ambient ultraviolet-B (UV-B) exposure reduces the risk for multiple sclerosis (MS) by 45% vs low exposure, according to results of a new study.

Using data from the Nurses’ Health Study cohort, the researchers examined 151 individuals with MS who had completed summer, winter, and lifetime sun exposure history questionnaires; participants were age-matched to a control group (n = 235).

____________________________________________________________________

RELATED CONTENT
The Role of Gut Microbiome in Multiple Sclerosis
Could Smoking Accelerate the Progression of MS?
____________________________________________________________________

The researchers categorized low UV-B exposure during the summer as up to 9 h/wk and high exposure as more than 10 h/wk. During the winter, low exposure was defined as up to 3 h/wk, and high exposure was more than 4 h/wk.

Results of the analysis showed that individuals who lived in areas with high exposure to UV-B had a 45% lower risk for MS than those who lived in areas with low exposure.

Lower risks were also found for medium or high exposure (51%-52%) at ages 5 to 15 years and at 5 to 15 years before MS onset.

In addition, at ages 5 to 15 years, living in a high UV-B area and having high summer sun exposure were associated with a lower MS risk (Relative risk, 0.45).

“Living in high ambient UV-B areas during childhood and the years leading up to MS onset was associated with a lower MS risk,” the researchers conclude. “High summer sun exposure in high ambient UV-B areas was also associated with a reduced risk.”

—Amanda Balbi

Reference:

Tremlett H, Zhu F, Ascherio A, Munger KL. Sun exposure over the life course and associations with multiple sclerosis [published online March 7, 2018]. Neurology. https://doi.org/10.1212/WNL.0000000000005257.