How Much Sunshine is Good for You?

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WITH SUMMER here, it's fair to ask: is sunshine a public-health menace or a savior? For the last 30 or 40 years, a loud anti-sunshine message has ruled the day. This has meant gallons of sunblock at the highest available SPF, long sleeves and floppy hats, even wetsuits for kids at the beach—all in the name of preventing skin cancer (and wrinkles).

It was the perfect intervention until, in the past decade or two, the vitamin-D enthusiasts stepped forward with a different argument. Vitamin D is produced by sunlight interacting with our skin—and the more the better, they say. It also can be absorbed in food as part of a healthy diet, but the sun-to-skin-to-bloodstream route is the more dependable. Many studies have suggested that vitamin-D deficiency leads to countless medical problems, from cancer and heart disease to dementia and arthritis. But as a general rule in medicine, when something is said to be a panacea, it is probably exactly the opposite. As a result, skeptics love to doubt the happy talk about vitamin D, though some health advantages, such as bone and muscle strength, are indisputable.

So how should we reconcile these dueling health messages, as those out to prevent skin cancer are pointing people one way while vitamin-D stalwarts are sending them in the opposite direction? The medical journal Anti-Cancer Agents and Medicinal Chemistry ran several pro–vitamin D articles earlier this year that wrestled with this conundrum, and the reviews demonstrated that a common ground could be found between the two camps.

Here are some simple steps: Avoid the power of noonday sun, and don't go overboard on the season's first day of sunbathing. Rather, soak up some rays in the morning and late afternoon. And sure, douse the kids in sunscreen, but don't go nuts over it. Learn to check your skin too—skin cancers, including melanoma, are generally curable when caught early. But most important of all, go outside a little and relax in the glory of summer.