Stronger effect of frequent sun protection
Previous studies have shown a link between sun exposure and MS. A study published in 2018 compared 2,251 patients with MS with 4,028 control persons who did not have MS. The participants were in Canada, Italy, and Norway.
In that study, for most of the patients with MS, the age of onset was older than 18 years. In that study, there was a nearly 50% increased risk among those with the lowest degree of summer sun exposure in comparison with those who had the highest level of exposure (risk ratio, 1.47).
Contrary to the current study, that study did show an effect of the use of sun protection – those with the lowest degree of sun exposure during summer and winter and the highest use of sun protection had the highest risk for MS. They had a 76% increased risk, compared with those who had the highest degree of sun exposure and the least use of sun protection (RR, 1.76).
Sandra Magalhaes, PhD, of the University of New Brunswick, Fredericton, Canada, who was first author on that study, noted that the new study of pediatric MS adds valuable evidence on the issue.
“This study is important, as it adds to the etiological literature on MS implicating relevance of sun exposure,” Dr. Magalhaes said.
“We have a number of studies that have demonstrated an important effect of reduced levels of sun exposure and increased risk of MS. However, these studies focus on adult-onset MS populations; rather, the new study adds to the existing literature, as it also implicates sun exposure in etiology of pediatric-onset MS,” she said.
Notably, their previous work, unlike the current study, showed that, among those who experienced low levels of sun exposure, the risk for MS was higher for those who used sunscreen frequently.
“Overall, in their limited time outdoors, use of sunscreen may further increase risk of MS, which makes sense, since limited time outdoors in less sun, adding sun protection means [exposure to] even less sun.”
The findings of both studies support the bulk of research indicating that sun exposure is beneficial with regard to MS.
“There is a need for promoting balanced safe sun practices to reduce disease burden, especially in countries and cultures where children spend a lot of time indoors,” Dr. Magalhaes said. “Sun exposure has a number of important physiological roles, including vitamin D synthesis but also immune system functioning.”
Mr. Sebastian and Dr. Magalhaes have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.