Scientists Say Sunshine May Prevent Skin Cancer

After years of telling people to avoid the sun to ward off skin cancer, scientists are now coming to the conclusion that moderate sun exposure is healthy.

Scientists Say Sunshine May Prevent Cancer (AP)

Scientists are excited about a vitamin again. But unlike fads that sizzled and fizzled, the evidence this time is strong and keeps growing. If it bears out, it will challenge one of medicine’s most fundamental beliefs: that people need to coat themselves with sunscreen whenever they’re in the sun. Doing that may actually contribute to far more cancer deaths than it prevents, some researchers think.

The vitamin is D, nicknamed the “sunshine vitamin” because the skin makes it from ultraviolet rays. Sunscreen blocks its production, but dermatologists and health agencies have long preached that such lotions are needed to prevent skin cancer. Now some scientists are questioning that advice. The reason is that vitamin D increasingly seems important for preventing and even treating many types of cancer. In the last three months alone, four separate studies found it helped protect against lymphoma and cancers of the prostate, lung and, ironically, the skin. The strongest evidence is for colon cancer.

Many people aren’t getting enough vitamin D. It’s hard to do from food and fortified milk alone, and supplements are problematic. So the thinking is this: Even if too much sun leads to skin cancer, which is rarely deadly, too little sun may be worse. No one is suggesting that people fry on a beach. But many scientists believe that “safe sun” — 15 minutes or so a few times a week without sunscreen — is not only possible but helpful to health.

The number of cases in recent years where medical science has created hysteria against behavior once considered perfectly fine–like eating bacon and eggs for breakfast or getting some sunshine and fresh air–only to have to reverse themselves after a number of years is growing.

Perhaps if we conducted medical research with standards at least as rigorous as those required by the social sciences, we could avoid this. I’m often shocked when I see that these widely-touted studies in leading medical journals are based on laughably small sample sizes and hand-selected groups that are obviously not representative of the general population.

Update (1201): Glenn Reynolds points to a related post from almost exactly a year ago by Bill Ardolino.

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James Joyner
About James Joyner
James Joyner is Professor and Department Head of Security Studies at Marine Corps University's Command and Staff College. He's a former Army officer and Desert Storm veteran. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. Michael says:

    Small correction (I think). I don’t think they said it would prevent SKIN cancer, but rather, cancers in general.

    I think the deal is that skin cancer, which is relatively easy to cure, may not be worth slathering yourself in sunscreen for if it turns out more deaths can be prevented if you DON’T screen out the sun.

  2. Terry says:

    “Perhaps if we conducted medical research with standards at least as rigorous as those required by the social sciences, we could avoid this.”

    Ouch. That was brutal.

  3. James Joyner says:

    “…and, ironically, the skin.”

  4. Bill from INDC says:

    James –

    I agree with you that these “reversals” are annoying (as my post indicates), but in this case it’s not a lack of research rigor that flaws the recommendations.

    Sun damage, premature aging and cancer association are rock solid, irrevocably tied to sun exposure, and this is some of the most validated research in the world.

    The first problem is, the recommendations adopted by the medical establishment take on this annoying, one-size-fits-all simplicity, something that’s deemed a requisite because patients/doctors apparently lack the ability to absorb, understand and apply complex advice.

    The second flaw specifically related to this (sun exposure) scenario, is that dermatologists study the effect of the sun on the skin, and don’t give a rats ass of focus to things like increased rates of colon cancer that may be a side effect of underexposure to the sun. When a dermatologist looks at reasearch that displays that sun damage occurs within 15 minutes of sun exposure, and watches as the rates of skin cancer spiral with the depletion of ozone and lifestyle choices to get baked by young people, they tailor their recommendations to their specialty.

    So to summarize a couple of the main difficulties with modern med recommendations:

    1. Simplified to a ridiculous degree, patronizing the ability of practitioners and patients to understand and correctly apply complex info.

    2. An inability for specialized practitioners and researchers to view the results of research within the context of the integrated function of the body.

    This second problem will become alleviated as information technology and research advances dramatoically within this next generation, I’d predict. I’d be careful about thinking of it as a dramatic “reversal,” as fears about skin damage from the sun are significant; I could write you a paper that’d make you want to dig an underground house.

    It’s just that a lot of dermatolgists insulted their patients with the overreactionary advice in the first place. And another huge subset of patients ARE burning themselves to death in the sun for an aesthetic.

  5. Bill from INDC says:

    Oh, and real quick – the way sunshine protects you from skin cancer is all about moderation and consistency.

    Many types of skin cancer, especially melanoma, are tied to acute burns. And this is very common in a society where office workers toil indoors all year and then take a 2 week vacation in Aruba.

    In contrast, a regular, small amount of sun exposure (20 minute sunny walks 3, 4, 5 times per week) slowly builds up the body’s defenses against the radiation, aquires the beneficial effects and avoids the acute burns that really mutate the crap out of DNA and jumpstart many skin cancers.

    That being said, the body’s DNA could/will mutate after awhile of regular, relatively minimal sun exposure, but the acute burns are much, much worse for you. And unfortunately, our modern lifestyle predisposes us to them.

  6. Bill from INDC says:

    “acquires” not “aquires”

  7. TomW says:

    At the NIH Conference On Cancer and Vitamin D* last October,
    one presenter indicated that for every 2 women who avoided melanoma
    by avoiding the sun, 26 got breast cancer….

    A major point was to get sun exposure – but avoid sun burn,

    * See URL:

  8. Clarity Jones says:

    Vitamin D is easy to obtain from food. Cod liver oil is a rich source. Cod liver oil obtained using modern methods is odorless and tasteless. Cherry flavor, mint flavor and orange flavor varieties are offered. The oil mixes easily into scrambled eggs, chowder, pancakes. biscuits.

    Other sources of Vitamin D are organ meats such as liver, brains, heart, kidney.

    Shark liver oil is another rich source of Vitamin D. Seal liver oil is a rich source of vitamin D.

    Plenty of options exist for getting adequate Vitamin D without resorting to Sun bathing. Sun exposure is unnecessary. You should wear sunscreen to prevent premature aging and cancer.

  9. McGehee says:

    Clarity, I read the article — it points out that getting Vitamin D from food alone isn’t sufficient. The best Vitamin D (the research clearly shows) is that your body manufactures for itself.

    With sunlight.