Pondering "sunscreen absolutism"

An article in The Atlantic considers the possibility that Americans' fear of skin cancer has resulted in too much avoidance of sun exposure.

Then, in 2023, a consortium of Australian public-health groups did something surprising: It issued new advice that takes careful account, for the first time, of the sun’s positive contributions. The advice itself may not seem revolutionary—experts now say that people at the lowest risk of skin cancer should spend ample time outdoors—but the idea at its core marked a radical departure from decades of public-health messaging. “Completely avoiding sun exposure is not optimal for health,” read the groups’ position statement, which extensively cites a growing body of research. Yes, UV rays cause skin cancer, but for some, too much shade can be just as harmful as too much sun.

It’s long been known that sun exposure triggers vitamin D production in the skin, and that low levels of vitamin D are associated with increased rates of stroke, heart attack, diabetes, cancer, Alzheimer’s, depression, osteoporosis, and many other diseases. It was natural to assume that vitamin D was responsible for these outcomes... 

But sunlight in a pill has turned out to be a spectacular failure. In a large clinical trial that began in 2011, some 26,000 older adults were randomly assigned to receive either daily vitamin D pills or placebos, and were then followed for an average of five years. The study’s main findings were published in The New England Journal of Medicine in 2018, and additional results were released in the same publication two years ago. An accompanying editorial, with the headline “A Decisive Verdict on Vitamin D Supplementation,” noted that no benefits whatsoever had been found for any of the health conditions that the study tracked. “Vitamin D supplementation did not prevent cancer or cardiovascular disease, prevent falls, improve cognitive function, reduce atrial fibrillation, change body composition, reduce migraine frequency, improve stroke outcomes, decrease age-related macular degeneration, or reduce knee pain,” the journal said. “People should stop taking vitamin D supplements to prevent major diseases or extend life.”..

Health authorities in some countries have begun to follow Australia’s lead, or at least to explore doing so. In the United Kingdom, for example, the National Health Service is reviewing the evidence on sun exposure, with a report due this summer. Dermatology conferences in Europe have begun to schedule sessions on the benefits of sun exposure after not engaging with the topic for years...

It turns out that UV light essentially induces the immune system to stop attacking the skin, reducing inflammation. This is unfortunate when it comes to skin cancer—UV rays not only damage DNA, spurring the formation of cancerous cells; they also retard the immune system’s attack on those cells. But in the case of psoriasis, the tamping-down of a hyperactive response is exactly what’s needed. Moreover, to the initial surprise of researchers, this effect isn’t limited to the site of exposure. From the skin, the immune system’s regulatory cells migrate throughout the body, soothing inflammation elsewhere as well...

That said, we now know that many individuals at low risk of skin cancer could benefit from more sun exposure—and that doctors are not yet prepared to prescribe it. A survey Neale conducted in 2020 showed that the majority of patients in Australia with vitamin D deficiencies were prescribed supplements by their doctors, despite the lack of efficacy, while only a minority were prescribed sun exposure. 

Much more at the link.  Please read the source material rather than relying on my selected excerpts.