February 6, 2013
A Little Sunlight May Keep Rheumatoid Arthritis At Bay For Women
Connie K. Ho for redOrbit.com — Your Universe Online
For retirees, Florida is considered one of the best places to retire — surf, sunny weather and relaxation. However, there may be more health benefits from this sunny locale than originally thought. A new study has revealed that sunlight could possibly help reduce the risk of rheumatoid arthritis in aging women.
Researchers found that the risk of developing rheumatoid arthritis could be decreased by regular exposure to sunlight, specifically ultraviolet B (UVB). According to the National Institute of Health, rheumatoid arthritis occurs when the body´s immune system attacks the joints, causing inflammation in the joints and surrounding tissue. The findings of the long-term study were recently published in the online edition of the Annals of the Rheumatic Disease.
"Differences in sun protective behaviors (i.e. greater use of sun block in younger generations) may explain the disparate results," the researchers wrote as a probable explanation for why the anti-arthritis benefits were only observed for older women.
The research study included participants in two phases of the U.S. Nurses´ Health Study (NHS). In one phase, researchers recorded the health of over 120,000 nurses beginning in 1976 through 2008. The nurses were between 30 and 55 years of age when phase one first started. The second phase (NHSII) recorded the health of another 115,500 nurses beginning in 1989 to 2009; these nurses were between 25 and 42 years of age at the start of the second phase. The scientists also used a UV-B flux, an assessment instrument that could help them assess UVB radiation based on the latitude, altitude and cloud cover of their location. The exposure of UV-B was then approximated based on the US state in which the nurses resided.
During the study period, 1,314 of the women developed rheumatoid arthritis. For participants who were in the first phase, there was a correlation between higher cumulative exposure to UVB and a lower risk of developing arthritis. The analysis demonstrated that the females who had the highest levels of exposure had a 21 percent lower chance of developing the disease. The researchers believe that the vitamin D produced in the body by exposure to sunlight helped protect the body against the potentially disabling inflammatory disorder.
However, in the NHSII phase of the study, the researchers did not see the same link between UV-B exposure and reduced risk of rheumatoid arthritis. The scientists propose that since the participants in NHSII were younger, they may have been more wary of the dangers associated with exposure to too much sunlight. The team of investigators was also unclear as to the period of life during which the protective impact of UV-B is effective.
"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 authors in the statement.
The findings in the study correlate to other studies that have looked at the relationship of geography, sunlight and the risk of developing rheumatoid arthritis. Outside experts believe that the study may also provide valuable insight into the development of rheumatoid arthritis.
"We cannot advocate everybody sitting in the sunshine all day to protect from rheumatoid arthritis, because UV-B burns people and increases the risk of skin cancer,” said Dr. Chris Deighton, president of the British Society of Rheumatology, in an interview with the BBC. "The treatment options in rheumatology have transformed the lives of patients with this crippling disease in recent years and anything that adds to our knowledge is welcomed."