Sunlight may protect against rheumatoid arthritis, reports a new study.
The sun's rays contain two types of ultraviolet radiation that reach the skin: ultraviolet A (UVA) and ultraviolet B (UVB). UVB radiation burns the upper layers of skin, causing sunburns. UVA radiation, which penetrates to the lower layers of the skin, causes tanning. UVA rays are considered the culprit in the aging of skin, and UVB rays are more often linked to skin cancer.
The recent study used data from the Nurses' Health Study and the Nurses' Health Study II; in which women were followed for 32 and 20 years, respectively. Researchers calculated the level of UVB radiation exposure, based on geographical latitude, altitude and level of cloud cover.
Over time, 1314 women developed rheumatoid arthritis. In the Nurses' Health Study, participants with the most UVB radiation exposure had a 21 percent lower chance of rheumatoid arthritis than the participants with the least UVB radiation exposure. However, in the Nurses' Health Study II, there was no significant association with level of UVB exposure and rheumatoid arthritis.
Because the women in the Nurses' Health Study II were younger, researchers suggested that increased use of sunscreen in the younger generation may explain the lack of association. Further research on this topic is warranted.
For more information UVA or UVB radiation, please visit Natural Standard's Health & Wellness Database.