- People who are
more exposed to the sun's rays are less likely to develop a neurological
condition called multiple sclerosis (MS).
- People who lived
in sunnier climates with the highest exposure to UV-B rays had 45% reduced
risk of developing MS.
- The UV-B rays
from the sun stimulate the production of vitamin D in the body which is
important in reducing the risk of MS.
Where a person lives and the ages at which they are exposed to the sun's
rays may play an important role in reducing the risk of multiple sclerosis
(MS), according to a new study. People who live in sunnier climates and are
more exposed to the sun's rays are less likely to develop MS later in life,
shows study. The study found that
exposure to the sun's rays during childhood and young adulthood reduced the
risk of MS.
The study is published
in the journal Neurology
Multiple Sclerosis and the Sun
is a disease that affects the
central nervous system that includes the brain and the spinal cord. In MS, the
protective layer of the neurons called the myelin is attacked by the immune system, thereby disabling neuronal
communication between the brain and the rest of the body.
Previous studies have linked low levels of vitamin D
an increased risk of MS. But exposure to the sun's rays, specifically the UV-B
rays help the body produce vitamin D and thereby plays an important role in
reducing the risk for MS.
‘Living in climates with high exposure to the sun's UV-B rays and getting that exposure during the ages of 5 to 15 lowers the risk of developing multiple sclerosis.’
"While previous studies have shown that more
sun exposure may contribute to a lower risk of MS, our study went further,
looking at exposure over a person's lifespan," said study author Helen
Tremlett, PhD, of the University of British Columbia in Vancouver, Canada.
The study included 151 women with MS and 235 women
of similar age without MS who were identified from the larger Nurses' Health
Study. About 98% of the participants were white
and 94% had fair to medium skin. The participants lived across the US in a
variety of climates. Among those with MS, the average age at onset was 40.
The participants were given questionnaires about
lifetime summer and winter sun exposure. Based on the answers to the
questionnaire, the women were divided into three groups: low, moderate and high
UV-B ray exposure.
- Based on place of living: Women
who lived in sunnier climates with the highest exposure to UV-B rays had
45% reduced risk of developing MS compared to women who lived in areas
with the lowest UV-B ray exposure.
- Based on age: Women
who lived in areas with the highest levels of UV-B rays between ages 5 to
15 had a 51% reduced risk of MS.
- Also, women who
spent more time outdoors in the summer during the ages 5 to 15 in
locations with high exposure to UV-B rays had a 55% reduced risk of
developing MS during adulthood compared to those with the lowest exposure.
"Our findings suggest that higher exposure to
the sun's UV-B rays, higher summer outdoor exposure and lower risk of MS
can occur not just in
childhood, but into early adulthood as well," said Tremlett.
Limitations of the study
- Sun exposure was self-reported by the
- Almost all participants were female and
white thereby the results of the study may not apply to other populations.
- Helen Tremlett, Feng Zhu, Alberto Ascherio and Kassandra L. Munger. Sun exposure over the life course and associations with multiple sclerosis. Neurology, March 7, 2018 DOI: 10.1212/WNL.0000000000005257