Sun Exposure May Help Lower Blood Pressure

By Jane Farrell

Exposure to sunlight has a newly found health benefit: reducing blood pressure and cutting the risk of heart attack and stroke, according to a new study.

The findings, published in the Journal of Investigative Dermatology, indicate that sunlight alters the level of nitric oxide (NO), a small messenger molecule, in skin and blood.

Martin Feelisch, Professor of Experimental Medicine and Integrative Biology at the University of Southampton, UK, comments: “NO along with its breakdown products, known to be abundant in skin, is involved in the regulation of blood pressure. When exposed to sunlight, small amounts of NO are transferred from the skin to the circulation, lowering blood vessel tone; as blood pressure drops, so does the risk of heart attack and stroke.”

Although it's well known that limiting exposure to sunlight helps prevent skin cancer, the study authors suggested that minimizing exposure may not be beneficial.

In the study, 24 healthy people were exposed to ultraviolet (UVA) light from tanning lamps for two sessions of 20 minutes each. In one session, the volunteers were exposed to both the UVA rays and the heat of the lamps. In another, the UV rays were blocked so that only the heat of the lamps affected the skin.

The results suggest that UVA exposure dilates blood vessels, significantly lowers blood pressure, and alters NO metabolite levels in the circulation, without changing vitamin D levels. 

Professor Feelisch adds: “These results are significant to the ongoing debate about potential health benefits of sunlight and the role of Vitamin D in this process. It may be an opportune time to reassess the risks and benefits of sunlight for human health and to take a fresh look at current public health advice. Avoiding excess sunlight exposure is critical to prevent skin cancer, but not being exposed to it at all, out of fear or as a result of a certain lifestyle, could increase the risk of cardiovascular disease. “We believe that NO from the skin is an important, so far overlooked contributor to cardiovascular health."

Feelisch said further research on the topic was necessary.