Sun exposure may decrease females' risk for rheumatoid arthritis

February 8, 2013

Topic: orthopaedic problem

Sun exposure may decrease females' risk for rheumatoid arthritis

According to a new study published in the online journal Annals of the Rheumatic Diseases, older women who spent routine time out in the sun throughout their lives may be less likely to develop rheumatoid arthritis than those who did not get plenty of sunlight. This association can give healthcare providers insight into individuals' likelihood of having the condition.

Rheumatoid arthritis is described as an inflammatory condition that causes affected individuals to experience discomfort, swelling, stiffness and loss of function in the joints, which could subsequently lead to other orthopaedic problems, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). It is the result of the immune system attacking the membrane lining the joints in the body.

In the U.S., rheumatoid arthritis affects approximately 1.3 million individuals, states the NIAMS. This equates to 0.6 percent of the total adult population currently residing in the country. Similarly to other forms of arthritis, the condition is more prevalent among women than men.

Researchers from the Harvard School of Public Health studied approximately 235,000 subjects who participated in the U.S. Nurses' Health Study that began in 1976 and continued through 2009. They identified 1,314 women who developed rheumatoid arthritis and took note of about how much UV-B exposure they had, and their states of residency.

The collected data revealed that the subjects with the highest predicted UV-B levels had a 21 percent reduced chance of developing rheumatoid arthritis, compared to those who had the lowest levels in the study.

"Our study adds to the growing evidence that exposure to UV-B light is associated with decreased risk of rheumatoid arthritis. The mechanisms are not yet understood, but could be mediated by the cutaneous production of vitamin D and attenuated by use of sunscreen or sun-avoidant behavior," concluded the study's investigators. 

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