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A walk in the sun might do more than one can think. It also alleviates the risk of getting rheumatoid arthritis, a recent study reveals.

The sun emits ultraviolet B rays or UVB rays which lower the chances of getting rheumatoid arthritis. However, these results of sunlight were evident in older women, as younger ones use protective sunscreen lotions to avoid the harmful effects of the sun. The study did not find a similar effect of sun among younger women.

U.S. Nurses' Health Study (NHS) was carried out in two phases and the first one monitored the health of over 120,000 nurses who were between 30 and 55 years of age in 1976 and kept a regular track of them till 2008. While the next phase or NHSII dealt with nurses between 25 and 42 years old in 1989 and all 115,500 of them were monitored till 2009.

The researchers used UV-B flux, an accurate measurement instrument of UVB exposure depending on latitude, altitude and cloud cover. The instrument measures UVB radiation in R-B units where if it reads 440 units for half an hour, it will give symptoms of sunburn in an individual. According to the average taken across the U.S., Alaska and Oregon measured exposure of 93 R-B units, while people in Hawaii and Arizona had an average UV exposure of 196 R-B units.

During the course of the NHS studies, 1,314 nurses developed rheumatoid arthritis and those who had higher UVB exposure had 21 percent less risk of getting the disease. This supports the studies that link geography to autoimmune disorder risks like type 1 diabetes, rheumatoid arthritis and others.

"Differences in sun protective behaviors (e.g. Greater use of sun block in younger generations) may explain the disparate results. 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," the author was quoted as saying in Medicalxpress.

The study was published online in the Annals of the Rheumatic Diseases.