Communicating Science 13w212

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Many have heard of the health benefits of vitamin D through sun exposure, but its recent media portrayals, especially during the summer months, have generally been negative due to the culture of sun tanning and its effects of prolonged UV exposure, such as cancer and premature skin aging. This has given the public reason to fear sun exposure and to justify staying indoors. Studies suggest, however, that there are more benefits to sun exposure than just vitamin D, but what exactly are they, and why would we risk getting skin cancer for these supposed benefits?

Firstly, we must discuss the effects of nitric oxides (NO) on our blood vessels. When inside the linings of our blood vessels, this compound binds to and activates specific enzymes, which trigger the relaxation of smooth muscle, resulting in the dilation of our blood vessels.  Professor Richard Weller of the University of Edinburgh, a longtime researcher in the roles of nitric oxide in human skin physiology, has shown in collaborated studies that sunlight aids in mobilising the nitric oxide species (taken in through our diet and natural production) that are stored in skin to the blood vessels, thus stimulating vasodilation. Blood pressure decrease associated with vasodilation lowers the risks of coronary related diseases, improving overall cardiovascular health.

For those attempting to replace sunlight exposure with vitamin D supplements, the study suggests otherwise. Particularly, it states that these cardiovascular health benefits are independent of vitamin D and are instead related to the nitric oxide mobilisation from the skin due to the sun’s UVA rays. In vitro tests through UVA irradiation onto skin has shown that it stimulates breakdown of the skin’s NO stores, releasing the nitric oxides. From these results, the added benefits of sun exposure that cannot be replaced by supplements is apparent.

However, the question that remains is whether or not these benefits outweigh the costs or risks. We should not deny the fact that skin cancer from overexposure to the sun is still a risk. In the video below, Dr. Michael Ruscio not only mentions the ideas covered by Weller, but also effectively includes examples of the most common cancers compared to skin cancer to put it into perspective.

As Ruscio emphasises in an example, although the skin is ranked 10th in the 10 cancer sites, the male genitalia (ranked 3rd) and lymphoma (ranked 9th) are higher on the list and have been shown to react beneficially to sun exposure. To quantify the amount of sunlight we should receive, he suggests approximately 30 minutes a day, keeping in mind the variation in our complexions (those with darker complexions to receive more, and those with lighter complexions to receive less).

In retrospect, the right amount of sun exposure can have great benefits to cardiovascular health by lowering blood pressure and decreasing risks of cardiovascular related diseases, but like everything else we expose our bodies to, it should be in moderation. By doing so, we can avoid the painful aftermath of sunburns after an eventful day at the beach and more importantly, the risk of skin cancer.

– Leslie Chiang