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Modest Sun Exposure a Good Way to Get Vitamin D Supply

By Michael Lasalandra
Beth Israel Deaconess Medical Center correspondent

Exposure to the sun’s rays is one way of getting the vitamin D we need for healthy bones. But is the risk of developing skin cancer too great to even step outside on a sunny day without a hat, long sleeves and sunscreen?

Many dermatologists and skin cancer specialists warn us to be wary of even a little sun exposure. On the other hand, others say some sunlight is absolutely necessary. The issue has been a hot one, particularly since the controversial book, The UV Advantage, by Dr. Michael Holick, a professor of dermatology at Boston University School of Medicine, was published in 2004. Holick was fired from his dermatology post for advocating sun exposure.

"There's a middle ground," says Dr. Robert Stern, Chief of the Department of Dermatology at Beth Israel Deaconess Medical Center and a professor at Harvard Medical School. “I think the risks of modest sun exposure are quite small and there are potential benefits. I’m not one who says never get any sun.”

Stern notes that adequate levels of vitamin D are needed to maintain good bone metabolism. “There’s no doubt about that,” he says.

At the same time, there is some evidence that having exposure to higher levels of vitamin D protects against some non-skin cancers, including breast cancer, although this evidence is less than definitive, he says. “I am generally impressed by this argument,” he adds.

There are three ways to get vitamin D — from sun exposure, from eating foods that are naturally rich in vitamin D, such as fatty fish, or foods that are vitamin D-enriched, such as milk and certain cereals; or, perhaps most conveniently, by taking a vitamin D supplement. Vitamin D supplements are inexpensive and available over the counter.

According to Stern, the amount of sun exposure needed to get an adequate level of vitamin D is quite modest, particularly in the summer.

“You don’t have to go out and bake to get enough Vitamin D,” he says. “A few minutes per day are all you need. You don’t need to lie out two hours by the pool. Five or 10 minutes of exposure to just the arms is enough to make plenty of vitamin D. Modest exposure, while trying to protect the head, neck, ears and hands, will give you sufficient vitamin D synthesis.”

And going outside is a good thing in and of itself, as it promotes physical exercise, Stern points out.
“One of the adverse consequences of being too zealous [about avoiding the sun] is that it decreases overall physical activity,” he says. “It’s clear that getting a little sun will keep you healthier overall than not going out at any time.”

But Stern warns that chronically exposed areas, such as the head and neck and back of arms and hands, should be protected and that getting sunburned “is not good for anybody.”

People who never go out in the sun or always cover up may be “sun phobes,” according to Stern. “Except for persons with photosensitivity diseases and taking certain medications, I don’t think it is reasonable to never go out in the sun,” he says. “People will be a lot happier if they go out to run or to play golf. I wish I was out in the sun today, with sunscreen on my face and other areas that will be exposed to the sun for more than a few minutes, having a good time.”

Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.

Posted June 2013

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Department of Dermatology
Beth Israel Deaconess Medical Center

330 Brookline Avenue
Boston, MA 02215

25 Boylston Street
Chestnut Hill, MA 02467

304 Chestnut Street
Needham, MA 02492