This one’s not just for exercisers: Information about sunscreen applies to everyone.

Sunscreen helps prevent skin cancer and other skin damage; vitamin D strengthens bones and is thought to have many other health benefits. So you want enough of both. Fortunately, this is a have-your-cake-and-eat-it-too scenario.

The sun’s ultraviolet rays help convert vitamin D from the food we eat into a form our bodies can use, said Darrell S. Rigel, a clinical professor of dermatology at Mount Sinai Icahn School of Medicine.

Some lab tests indicated that sunscreen might hamper this process, but in real-life use, that’s not the case, Rigel said. He said sunscreen is tested at two milligrams per square centimeter, an amount much greater than anyone would actually apply. (“You’d be as white as that door behind you,” he said. For the record, the door behind me was very white.)

Your body can convert only a fixed amount of vitamin D a day, Rigel said. Once you reach that level, “it’s basically like the bucket’s full and it won’t convert any more that day until the bucket empties a little bit and there’s room for it.”

The average person’s bucket will be filled if they step outside for just five to 10 minutes a day, he said, even if only their face and hands are uncovered and even if they’re wearing a sunscreen with a high sun protection factor (SPF). If more skin is exposed, it takes even less time. So most people get plenty of sun in the course of a normal day.

But if his patients are worried about a lack of vitamin D, or if a blood test shows they are deficient, Rigel suggests keeping the sunscreen, SPF 50 or more, and taking a daily 1,000 IU dose of over-the-counter supplement vitamin D3 to top off the bucket. That type of vitamin D is pre-converted, he said — no sun needed.

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