Our Understanding of Sun Exposure and Health Keeps Evolving

Myung Jung Kim/PA Wire

Controversial new research is upending the narrative about sun exposure and vitamin D: that the most reliable way to avoid skin cancer is to avoid excess sunlight, always wear sunscreen, and to offset these measures by taking vitamin D supplements. As Rowan Jacobsen reports in Outside, D supplements are not very effective, and a group of scientists have discovered that the relationship between sun exposure and skin cancer is far more complex than we thought. One Journal of Internal Medicine article phrased it this way: “Avoidance of sun exposure is a risk factor of a similar magnitude as smoking, in terms of life expectancy.” But don’t call this all counterintuitive.

When I spoke with Weller, I made the mistake of characterizing this notion as counterintuitive. “It’s entirely intuitive,” he responded. “Homo sapiens have been around for 200,000 years. Until the industrial revolution, we lived outside. How did we get through the Neolithic Era without sunscreen? Actually, perfectly well. What’s counterintuitive is that dermatologists run around saying, ‘Don’t go outside, you might die.’”

When you spend much of your day treating patients with terrible melanomas, it’s natural to focus on preventing them, but you need to keep the big picture in mind. Orthopedic surgeons, after all, don’t advise their patients to avoid exercise in order to reduce the risk of knee injuries.

Meanwhile, that big picture just keeps getting more interesting. Vitamin D now looks like the tip of the solar iceberg. Sunlight triggers the release of a number of other important compounds in the body, not only nitric oxide but also serotonin and endorphins. It reduces the risk of prostate, breast, colorectal, and pancreatic cancers. It improves circadian rhythms. It reduces inflammation and dampens autoimmune responses. It improves virtually every mental condition you can think of. And it’s free.

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