Sunlight: Friend, foe or frenemy?

Pastiness [pey-stee-ness] – a modern state of human evolution secondary to clothing and primarily indoor habitation allowing for long-term high latitude colonization.

“When our ancestors lived outdoors in tropical regions and ran around half naked, this wasn’t a problem.”

Rowan Jacobsen

And with that, I present today’s controversy both shaken and stirred.

Jacobsen’s article in Outside magazine suggests that our current stringent-to-no-end American dermatologic guidelines – i.e. dunking one’s self, family and dog into a vat of sunscreen upon venturing outside – may be barking up the wrong proverbial tree. 

Fist, a little historical physiology.

In 1831 while vacationing on the H.M.S. Beagle, a young naturalist named Charles Darwin debated skin color among race and its correlation with immunity from “certain vegetable poisons and…certain parasites.” While comparing humans with a variety of animal kingdom fame, he noted accurately that skin – our largest organ – is essential for our survival. It regulates body temperatures, acts as a first-line defense from microbes and specific to our topic today, harbors a specialized dark pigment producing cell, the melanocyte.

The primary job of the humble melanocyte is to create a pigment called melanin, which absorbs harmful ultraviolet B radiation produced by the sun. This of course helps prevent our delicate DNA from being shredded, reformed and mutated. Mutations (despite comic book adaptations) are typically things one should seek to avoid. This means the more melanin one has, the darker one’s skin and the less susceptible to sunburn and DNA damage one is. For example, African-Americans have an intrinsic sun protection factor (SPF) estimated to be ten times greater than those with light skin. This shows at a population level as African-Americans have a smaller incidence of melanoma.

For the curious. It stands to reason that Darwin would have killed to know how our skin color develops.

The Pandemic

Now that everyone’s sweating just thinking about the chain fusion reactions going on in the sun, I’d like to introduce an idea: there is currently a global pandemic. Not the zombie apocalypse. Not yet. But this pandemic is nearly as widespread and is known as vitamin D deficiency, a known highly complex health issue correlated with autoimmune, cardiovascular and psychiatric disease as well as generalized inflammatory states within the body.

But please kind sir or madame. Before crying havoc and letting slip words of war, it’s true that sunlight exposure remains indisputably linked with basal, squamous and the dreaded melanoma skin cancers.  Make no mistake, melanoma is deadly, however recent contrarian evidence has shown that perhaps, just perhaps, the sun is not to be singularly associated as a fiery ball of melanomic death.

The Research

Cue either the Imperial March or the Star Wars Main Theme depending on which side of the argument your mind has already wandered to.

A questionably non-fictional representation of Pelle Lindqvist, Richard Weller, et al. , as described below.

A group of dermatologically inclined rebels reminiscent of the Rebel Alliance have struck back at the American medical majority, inspiring a new hope in the sun-loving hive of well-tanned scum and villainy. These rebels have suggested for example, that oral Vitamin D supplementation for hypovitaminosis D is inadequate and that sunlight is a simple cost efficient alternative.

Enter senior research fellow in obstetrics and gynecology Pelle Lindqvist at the Karolinska Institute (presumably on Hoth) who has published extensively on the effects of sunlight mediating risk in various disease states such as blood clots, diabetes, endometrial cancer. His most recent manuscript reports that in the ~30,000 strong population of Swedish women followed by his group in the Melanoma in Southern Sweden study, their life expectancy was 1-2 years longer if they had more sun exposure. He concludes: “The introduction of sensible sun exposure recommendations might improve public health.”

Interesting population level study.

Enter research dermatologist Richard Weller at the University of Edinburgh (presumably on Coruscant) who has produced other interesting publications. For instance, he found that nitric oxide – a molecule naturally created by the endothelial cells lining blood vessels – was stimulated by sunlight, causing blood vessels to dilate, thereby decreasing blood pressure.  This finding has served as the impetus towards a trial looking into the effects of ultraviolet A on mild hypertension. This is not insignificant considering that cardiovascular disease and overall mortality (as I previously posted) is directly correlated with latitude from the equator.

Interesting basic science study.

Anybody wavering yet?

“What’s counterintuitive is that dermatologists run around saying, ‘Don’t go outside, you might die.’” 

Richard Weller


Overall, Jacobsen has a wonderful point in his piece: that the risks and benefits of sunlight are not clear cut. But as rebel data accumulates, will professional thought change as evidence is mulled?  Will public perception change, in this era of distrust? While some sun exposure is likely beneficial, we’re a ways from writing personalized sun exposure scripts.

But remember, because our cells/DNA are under constant assault everyday – not just from sunlight but also from normal physiologic processes within our bodies (a topic for another time) – researchers will continue pushing to unravel the mysteries of aging and disease. And we stay raptly attuned in this case, for further findings on sunlight from the rebel alliance, due in the near future as outlined below.


  • Tennis is the sport associated with the greatest longevity, so how’s the prevalence break down for that population when it comes to skin cancers and Vitamin D associated disease status etc.?
  • Given that our ancestors went about their business naked throughout the seasons, what are the gains from consistent, non-burn sun exposure which cause melanocytes to further produce protective pigment? A question best directed towards the I-kid-you-not Triennial International Pigment Cell Conference (IPCC) researchers probably. Alas, I don’t know any.
  • Can precision medicine and public health (which deals with prevention) aid one another at this juncture?
  • Stay tuned for Weller’s study results where he tracked 340,000 folks around the U.S. to discover whether the relationship between sunlight and lowered blood pressure exists.  These results (and others forthcoming) may increase the pressure on the American Academy of Dermatology to alter guidelines directed at sun avoidance as other international dermatologic academies already have.
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