Sunshine May Lower Multiple Sclerosis Risk
Prolonged, Moderate Exposure to the Sun's Rays May Fight MS
WebMD News Archive
Jan. 14, 2004 -- Living in a sunny place may lower a person's
risk of developing multiple sclerosis.
A new study shows that prolonged exposure to low levels of
solar radiation may have a protective effect against the disease.
The exact cause of multiple sclerosis is unknown, but previous
research has shown that the immune disorder is more common in areas farther
away from the equator -- areas with fewer hours of sunlight. For example,
multiple sclerosis is more common in Canada and the northern states of the U.S.
than in the southern states.
For that reason, researchers have speculated that sunshine
might protect against the disease, but there has been little scientific
evidence to back up that theory.
But in this study, researchers used the frequency of skin cancer as a marker for sun exposure and found skin cancer was indeed less
common among people with MS.
Sunshine May Protect Against Multiple Sclerosis
The study, published in the January issue of the Journal of
Epidemiology and Community Health, compared cancer rates among more than
5,000 people with multiple sclerosis and 430,000 English people with other
nerve or autoimmune conditions.
Researchers found that the prevalence of skin cancers in people
with MS was significantly lower than in the comparison group. This difference
was greatest among skin cancers other than melanoma.
Most skin cancers are closely associated with prolonged,
continuous exposure to sunshine, but melanoma is the type of skin cancer most
likely to be the result of brief but intense periods of exposure to very hot
Researchers say previous studies show that a minimum of
sunlight exposure throughout the year may help protect against multiple
They suggest that sunshine may interfere with the development
of multiple sclerosis by affecting the immune system response, possibly through
the production of vitamin D and melatonin (substances produced in the body in
response to sun exposure).