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Childhood
Sun Exposure Lowers MS Risk
People who spent more time in the sun as children may have a
lower risk of developing multiple sclerosis (MS) than people who
had less sun exposure during childhood, according to a recent
study published in the latest issue of Neurology, the medical
journal of the American Academy of Neurology.
For the study, researchers surveyed 79 pairs of identical twins
with the same genetic risk for MS in which only one twin had MS.
The twins were asked to specify whether they or their twin spent
more time outdoors during hot days, cold days, and summer, and
which one spent more time sun tanning, going to the beach and
playing team sports as a child.
The study found the twin with MS spent less time in the sun as
a child than the twin who did not have MS. Depending on the activity,
the twin who spent more hours outdoors had a 25 to 57 percent
reduced risk of developing MS. For example, the risk of developing
MS was 49 percent lower for twins who spent more time sun tanning
than their siblings.
“Sun exposure appears to have a protective effect against MS,”
said study authors Talat Islam, MBBS, PhD, and Thomas Mack, MD,
MPH, with the Keck School of Medicine of the University of Southern
California in Los Angeles. “Exposure to ultra violet rays may
induce protection against MS by alternative mechanisms, either
directly by altering the cellular immune response or indirectly
by producing immunoactive vitamin D.”
The study also found the protective effect of sun exposure was
seen only among female twin pairs, but Mack says this novel finding
must be viewed with caution since only a few male twins were involved
in the study.
“Our findings note the importance of sun exposure among people
with identical genetic risk for MS,” said Mack. “High priority
should be given to research into how sun exposure reduces MS risk
if we are to unravel the mystery of what causes MS.”
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