A group of researchers from UK applied to healthy volunteers participating in the study a dose of ultraviolet A ( UVA ) in his laboratory , equivalent to that received by exposing summer sun for 30 minutes in Spain . As a result , the blood vessels of the participants dilated, and his blood pressure dropped , the researchers reported .

Hypertension can lead to potentially fatal cardiovascular diseases such as heart failure or stroke, although many people do not even know they have it .

A number of risk factors for hypertension, including smoking , physical inactivity and excess salt in the diet, are old acquaintances . However sunlight and the potential contribution of the skin in its regulation has never been studied .

While no one knows exactly what the mechanism by which sun exposure can reduce blood pressure, the researchers suggest that a compound called nitric oxide and other chemicals derived from it , including nitrite and nitrate play a role .

Scientists known as nitric oxide acts in the regulation of blood pressure. The cells of the inner lining of blood vessels produce nitric oxide to dilate the vessels, lowering blood pressure against which the heart has to work.

While we can find a little of nitric oxide and its derivatives in blood, there is a much larger deposit on the skin . Martin Feelisch , professor of experimental medicine and integrative biology at the University of Southampton, and his team propose that sunlight somehow mobilizes these nitric oxide molecules passing from the blood to the skin , where they cause dilation of blood vessels reducing blood pressure.

Their results support their hypothesis , since alternative explanations that the fall in blood pressure produced by the warmth of the light, or changes in the consumption of nitrite or nitrate by the participants in the study, did not occur during the proof .

If confirmed by further research , the results of this study could change how the balance between health risks and benefits of sun exposure is assessed , the authors say in the study published in the Journal of Investigative Dermatology (Abstract) .