Vitamin D, Sunlight, and Skin Cancer: Walking the Tightrope

PJ Hamel Health Guide
  • Sufficient levels of vitamin D in your system are essential to bone health. And one of the easiest, fastest, and certainly the least expensive way to “take” vitamin D is via the sun: this key vitamin is synthesized when your skin is exposed to sunlight’s ultraviolet (UV) rays. But cancer exports warn us about the dangers of skin cancer (melanoma) due to UV exposure. How do you both maintain vitamin D levels, and protect yourself against cancer?

    How much vitamin D is in fortified milk? In yogurt? Or in cereal?

    Do you know how much vitamin D you get by taking the ever-popular cod liver oil?

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    How much vitamin D do you need every day – not only to maintain bone health, but to potentially reduce your risk of cancer, diabetes, and a host of other ills?

    It all seems so complicated, doesn’t it? How did people stay healthy 200 years ago, when no one had ever heard of vitamin D, let alone spent time worrying about getting enough of it?

    The answer is, our Founding Fathers didn’t say healthy; they died much younger than we do now, and from a host of ailments. But for the most part, they weren’t suffering from vitamin D deficiency.

    Why not?

    Because before researchers proved the link between sun exposure and skin cancer, most people got more than enough sun to ensure production of all the vitamin D their bodies needed, without worrying about either diet, or vitamin pills.

    Vitamin D – “the sunshine vitamin” – is produced naturally when we expose our skin to the ultraviolet (UV) rays in sunlight. Sunlight is free, and easy to obtain. We don’t have to do a blessed thing, other than spend a short amount of time outdoors during the daytime, to ensure we get all the vitamin D our bodies need.

    But clearly, it’s not that simple. Not these days, when everywhere you turn you’re warned of the dangers of sunlight, and how sun block (minimum SP30, please) is key to preventing melanoma – skin cancer.

    Unfortunately, sun block is also key to preventing your body from manufacturing the vitamin D it needs.

    So we’re right back to fortified dairy products, cereal, cod liver oil, and supplements – right?

    Well, not so fast. There may be room for compromise here – depending on your personal capacity for risk.

    The National Cancer Institute, my “go to” source for all things cancer-related, unfortunately takes a fence-sitting approach to the vitamin D/sunlight/skin cancer issue. Here’s what the NCI Web site says about relying on the sun as a source for vitamin D:

    “Although people obtain some vitamin D from dietary sources, most vitamin D is made in the body after the skin is exposed to sunlight. Despite the known and potential health benefits of vitamin D, increasing sun exposure increases the risk of skin cancer. In general, most experts believe that people should continue to use sun protection when UV levels are moderate or higher. Some researchers have suggested that brief daily exposure to UV will ensure adequate vitamin D production, but many variables (such as skin color, latitude, and season) can affect the production of vitamin D, and such recommendations have proven controversial. Other experts recommend vitamin D supplementation to avoid the problem of increasing skin cancer risk.”  

  • Not too illuminating, eh?

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    The National Institutes of Health, via its Office of Dietary Supplements, ventures a bit farther out on the limb, saying, “10 to 15 minutes of sun exposure to face, hands, arms, or back without sunscreen at least twice a week is generally enough to produce adequate vitamin D.”

    Well, that seems safe enough… doesn’t it?

    Not according to the Skin Cancer Foundation, which advocates strongly against relying on sunlight to ensure sufficient vitamin D levels.

    An article on, the foundation’s Web site, says in part, “…all unprotected UV exposure contributes to cumulative skin damage, accelerating aging and increasing our lifetime risk of skin cancer.”

    That same article quotes Dr. Deon Wolpowitz and Dr. Barbara Gilchrest of Boston University’s department of dermatology, authors of a recent study examining the relationship between sunlight and vitamin D. Wolpowitz and Gilchrest write, “The tradeoff of vitamin D production today for photoaging and skin cancer decades hence may have made sense millennia ago, when life expectancy was 40 years or less, but it’s a poor exchange when life expectancy has doubled… and one in three Caucasians develops skin cancer.”

    There are definitely those, and my research seems to show they’re in the majority, who advocate total reliance on diet and supplements for vitamin D, with NO sun exposure without protection.

    But in reality, how many of us apply sunscreen to our hands and neck and any other exposed parts of our bodies each and every day when we walk out the door and into the sunlight?

    If you work indoors, there’s a good chance your exposure to sunlight when it’s at its strongest (read: most likely to cause skin cancer) is minimal, Monday through Friday.

    But when you casually go out on a string of errands mind-morning on Saturday; or do lawn chores after church on Sunday, is every part of your body shielded from the sun – always?

    I doubt it. Remember, 10 to 15 minutes twice weekly is what our government (hesitatingly) tells us may be sufficient for manufacturing vitamin D. And I’d bet the vast majority of us get at least that amount of sunlight without even thinking about it.

    So pay attention to your diet; and take supplements, if you want to raise your vitamin D intake beyond current government recommendations.

    But stressing over balancing the best natural source for vitamin D – sunlight – with the dangers of skin cancer probably shouldn’t be high on your list of worries. Apply sunscreen when you’ll be out in the sun for prolonged periods. And enjoy those stray moments of unprotected sun exposure; they’re raising your vitamin D level.

Published On: November 16, 2011