PROBLEM: Even as I write this, CNN is reporting that the FDA has proposed tighter regulations for tanning beds. An unrelated email from the Yale School of Public Health arrives to inform me once again of the link between indoor tanning and skin cancer (people who use UV-based sun lamps have a 75 percent increased risk of melanoma). And yet, for whatever reason, there are dermatologists out there advocating the potential health benefits of UVA-exposure.
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METHODOLOGY: A research team that includes Richard Weller, a senior lecturer in dermatology at the University of Edinburgh, and other members of his department, put 18 volunteers in their early twenties beneath tanning lamps. They did so twice, exposing them once to UVA rays and once to just really hot lights for twenty minutes.
RESULTS: The participants' heart rate rose slightly when they were exposed to UVA radiation. And for an hour after they left the tanning booth, they experienced significant decreases in blood pressure, of around 2 mmHg, driven by decreases in diastolic blood pressure of up to 5 mmHG (systolic blood pressure was not affected). These effects, which may be attributable to improved circulation caused by reduced levels of nitrate in the skin, were not seen in those exposed only to heat.
Blood tests showed that the participants' vitamin D levels remained constant, suggesting that vitamin D, which is usually associated with sunlight's benefits, wasn't responsible for the changes.
IMPLICATIONS: The researchers (again, dermatologists) are reasoning that since high blood pressure is responsible for a lot more death -- through heart disease and stroke -- than skin cancer, then tanning, which they extrapolate to natural sunlight exposure, might actually be worth the risk. Which is sure to go over well when they present their findings Friday at an international dermatology conference. Even if they attribute the health benefits, as they do in their press release, not to tanning lamps but to the more innocuous-sounding "sunshine."
As the authors write, every reduction in blood pressure of 2mmHg, at a population level, reduces the risk of heart disease and stroke by 7 and 10 percent, respectively. They don't specify how much time spent soaking in UV rays might achieve the ideal balance of potential benefit to potential harm, though they say that's something they plan to look into next. In the meantime there are still many safer ways of reducing blood pressure.
The study "UVA lowers blood pressure and vasodilates the systemic arterial vasculature by mobilisation of cutaneous nitric oxide stores" will be presented at the International Investigative Dermatology conference.
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