SUNSHINE LINKED TO LOWER RHEUMATOID ARTHRITIS RISK
Older
women who’ve had regular exposure to sunlight may be less likely to develop
rheumatoid arthritis, new findings indicate.
This
beneficial effect — which is believed to be due to ultraviolet B (UV-B) in
sunlight — was only evident in older women. This may be because younger women
are more aware of the skin-related hazards of sunlight and take more steps to
limit their exposure, the researchers said.
For
the study, the investigators looked at about 235,000 participants who took part
in two phases of the U.S. Nurses’ Health Study. The first phase began in 1976
with nurses aged 30 to 55 and continued until 2008. The second phase began in
1989 with nurses aged 25 to 42 and continued until 2009.
By
the end of the two phases, 1,314 of the women had developed rheumatoid
arthritis, according to the study published in the current online edition of
the journal Annals of the Rheumatic Diseases.
The
nurses’ UV-B exposure was estimated based on data from the states where they
lived while taking part in the study. Likely estimates of their UV-B exposure
at birth and by age 15 were also included.
Among
women in the first phase of the Nurses’ Health Study, those with the highest
estimated levels of UV-B exposure were 21 percent less likely to develop
rheumatoid arthritis than those with the lowest levels.
However,
no such association between UV-B exposure and rheumatoid arthritis risk was
seen among women in the second phase. These women were younger than those in
the first phase and may have been more aware about the dangers of too much sun
exposure and avoided it, the study authors suggested.
“Our
study adds to the growing evidence that exposure to UV-B light is associated
with decreased risk of rheumatoid arthritis,” concluded Dr. Elizabeth Arkema,
of the department of epidemiology at Harvard School of Public Health, and
colleagues.
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