Study: UV Exposure Lowers Blood Pressure
As reported by ScienceDaily (01/14) Here Comes The Sun To Lower Your Blood Pressure -
Exposing skin to sunlight or tanning lamps may help to reduce blood pressure and
thus cut the risk of heart attack and stroke, a study published in the Journal
of Investigative Dermatology suggests.
Research carried out at the Universities of Southampton and Edinburgh shows that
sunlight alters levels of the small messenger molecule, nitric oxide (NO) in
the skin and blood, reducing blood pressure.
Martin Feelisch, Professor of Experimental Medicine and Integrative Biology at
the University of Southampton, 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."
While limiting sunlight exposure is important to prevent skin cancer, the
authors of the study, including Dr Richard Weller of the University of
Edinburgh, suggest that minimising exposure may be disadvantageous by
increasing the risk of prevalent conditions related to cardiovascular disease.
Cardiovascular disease, often associated with high blood pressure, accounts for
30 per cent of deaths globally each year. Blood pressure and cardiovascular
disease are known to vary according to season and latitude, with higher levels
observed in winter and in countries further from the equator, where ultraviolet
radiation from the sun is lower.
During the study, the skin of 24 healthy individuals was 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. 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.
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. Perhaps with the exception of bone
health, the effects of oral vitamin D supplementation have been disappointing.
"We believe that NO from the skin is an important, so far overlooked contributor
to cardiovascular health. In future studies we intend to test whether the
effects hold true in a more chronic setting and identify new nutritional
strategies targeted at maximizing the skin's ability to store NO and deliver it
to the circulation more efficiently."