Sunlight exposure may reduce blood pressure

January 20th, 2014 by Nature

The sun over Guernsey on 21 October 2011 (click image to expand - ©RLLord)

The sun over Guernsey on 21 October 2011 (click image to expand – ©RLLord)

Sunlight exposure may reduce blood pressure by altering nitric oxide (NO) levels in skin and blood, according to a study published in the Journal of Investigative Dermatology.

While limiting sunlight exposure is important to prevent skin cancer, the authors from the University of Southampton and the University of Edinburgh suggest that minimizing exposure may be disadvantageous as it may increase the risk of prevalent conditions related to cardiovascular disease.

Cardiovascular disease, often associated with high blood pressure, accounts for 30% of deaths globally each year.

Blood pressure and cardiovascular disease are known to vary according to both season and latitude, with higher levels observed in winter and in countries further from the equator, where ultraviolet radiation from the sun is lower.

The molecular basis for this association is unclear, but Richard Weller, Martin Feelisch and colleagues hypothesized that metabolites of NO, known to be abundant in skin, may be involved in the regulation of blood pressure.

They exposed the skin of 24 healthy individuals to a dose of Ultraviolet A (UVA) equal to spending around 30 minutes in natural sunlight.

Their results suggest that UVA exposure dilates blood vessels, significantly lowers blood pressure, and alters NO metabolite levels in the circulation.

Further experiments indicate that pre-formed stores of NO in the upper skin layers are involved in mediating these effects.

The data are consistent with the seasonal variation of blood pressure and cardiovascular risk at temperate latitudes.

The authors suggest that these findings have implications for public health advice, and propose that it is time to reassess the risks and benefits of sunlight exposure.


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