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Is Sunscreen the New Margarine?<br>Current guidelines for sun exposure are unhealthy and unscientific, controversial new research suggests—and quite possibly even racist. How did we get it so wrong?

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Is sunscreen doing more harm than good? (Photo: Geraldine Sy)

Updated May 31, 2024 09:38AM

These are dark days for supplements. Although they are a $30-plus billion market in the United States alone, vitamin A, vitamin C, vitamin E, selenium, beta-carotene, glucosamine, chondroitin, and fish oil have now flopped in study after study.

If there was one supplement that seemed sure to survive the rigorous tests, it was vitamin D. People with low levels of vitamin D in their blood have significantly higher rates of virtually every disease and disorder you can think of: cancer, diabetes, obesity, osteoporosis, heart attack, stroke, depression, cognitive impairment, autoimmune conditions, and more. The vitamin is required for calcium absorption and is thus essential for bone health, but as evidence mounted that lower levels of vitamin D were associated with so many diseases, health experts began suspecting that it was involved in many other biological processes as well.

And they believed that most of us weren’t getting enough of it. This made sense. Vitamin D is a hormone manufactured by the skin with the help of sunlight. It’s difficult to obtain in sufficient quantities through diet. When our ancestors lived outdoors in tropical regions and ran around half naked, this wasn’t a problem. We produced all the vitamin D we needed from the sun.

But today most of us have indoor jobs, and when we do go outside, we’ve been taught to protect ourselves from dangerous UV rays, which can cause skin cancer. Sunscreen also blocks our skin from making vitamin D, but that’s OK, says the American Academy of Dermatology, which takes a zero-tolerance stance on sun exposure: “You need to protect your skin from the sun every day, even when it’s cloudy,” it advises on its website. Better to slather on sunblock, we’ve all been told, and compensate with vitamin D pills.

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Yet vitamin D supplementation has failed spectacularly in clinical trials. Five years ago, researchers were already warning that it showed zero benefit, and the evidence has only grown stronger. In November, one of the largest and most rigorous trials of the vitamin ever conducted—in which 25,871 participants received high doses for five years—found no impact on cancer, heart disease, or stroke.

How did we get it so wrong? How could people with low vitamin D levels clearly suffer higher rates of so many diseases and yet not be helped by supplementation?

As it turns out, a rogue band of researchers has had an explanation all along. And if they’re right, it means that once again we have been epically misled.

These rebels argue that what made the people with high vitamin D levels so healthy was not the vitamin itself. That was just a marker. Their vitamin D levels were high because they were getting plenty of exposure to the thing that was really responsible for their good health—that big orange ball shining down from above.

One of the leaders of this rebellion is a mild-mannered dermatologist at the University of Edinburgh named Richard Weller. For years, Weller swallowed the party line about the destructive nature of the sun’s rays. “I’m not by nature a rebel,” he insisted when I called him up this fall. “I was always the good boy that toed the line at school. This pathway is one which came from following the data rather than a desire to overturn apple carts.”

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Weller’s doubts began around 2010, when he was researching nitric oxide, a molecule produced in the body that dilates blood vessels and lowers blood pressure. He discovered a previously unknown biological pathway by which the skin uses sunlight to make nitric oxide.

It was already well established that rates of high blood pressure, heart disease, stroke, and overall mortality all rise the farther you get from the sunny equator, and they all rise in the darker months. Weller put two and two together and had what he calls his “eureka moment”: Could exposing skin to sunlight lower blood pressure?

Sure enough, when he exposed volunteers to the equivalent of 30 minutes of summer sunlight without sunscreen, their nitric oxide levels went up and their blood pressure went down. Because of its connection to heart disease and strokes, blood pressure is the leading cause of premature death and disease in the world, and the reduction was of a magnitude large enough to prevent millions of deaths on a global level.

True, the sun worshippers had a higher incidence of [melanoma]—but they were eight times less likely to die from it.

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Wouldn’t all those rays also raise rates of skin cancer? Yes, but skin cancer kills surprisingly few people: less than 3 per 100,000 in the U.S. each year. For every...