Is Sunscreen the New Margarine?

Is Sunscreen the New Margarine? By Rowan Jacobsen.

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. …

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. …

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. …

As it turns out, a rogue band of researchers … 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. …

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.

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 person who dies of skin cancer, more than 100 die from cardiovascular diseases. …

In a 2016 study published in the Journal of Internal Medicine, [Pelle] Lindqvist’s team [at Sweden’s Karolinska Institute] put it in perspective: “Avoidance of sun exposure is a risk factor of a similar magnitude as smoking, in terms of life expectancy.” …

[ Richard Weller’s] largest study [at the University of Edinburgh] yet is due to be published later in 2019. For three years, his team tracked the blood pressure of 340,000 people in 2,000 spots around the U.S., adjusting for variables such as age and skin type. The results clearly showed that the reason people in sunnier climes have lower blood pressure is as simple as light hitting skin.

Reader Joanne:

On supplements, what matters is blood levels not supplement levels. D on its own can be detrimental if you don’t also have enough Vitamin K, which is hard to get and needs leafy greens. Nearly all single supplement studies fail to show a benefit. The problem with single supplement studies is that our bodies need many vitamins, not just one.