By the turn of the 20th century, rickets, the vitamin D deficiency disease, was rampant, thanks to city life with the shade of buildings and coal soot in the air. The dairy industry jumped at the opportunity to fortify milk with vitamin D, and so did the beer industry. According to one print ad: “Beer is good for you—but Schlitz, with Sunshine Vitamin D, is extra good for you…[so] drink Schlitz regularly—every day.” There are, of course, healthier fortified options, like vitamin D-fortified orange juice, but to reach recommended intake levels, it could take 15 to 20 cups of fortified milk, beer, and/or juice a day. As I discuss in my video The Risks and Benefits of Sensible Sun Exposure, to get those kinds of doses, it really comes down to sun or supplements.

Sunlight supplies 90 to 95 percent of vitamin D for most people. The threat of skin cancer is real, however it’s mostly from chronic excessive sun exposure and sunburns. “There is little evidence that minimal sensible exposure to sunlight will considerably increase the risk of skin cancer”—though why accept any risk when we can get our vitamin D just from supplements?

For the sake of argument, what if there were no supplements available? What if we were just trying to balance the positive and negative effects of sun exposure? On one side, we have entities like the American Academy of Dermatology that recommend that “no one should ever be exposed to direct sunlight without sun protection.” After all, the UV rays in sun are proven carcinogens, responsible for more than half of all Caucasian malignancies, blaming the tanning industry for downplaying the risk.

Even those who accept research dollars from the tanning industry acknowledge that excessive sun exposure can increase skin cancer risk, but argue for moderation, advocating for “sensible sun exposure” and blaming the sunscreen industry for overinflating the risk. However, it’s harder to impugn the motives of the dermatologists, who are essentially arguing against their financial interest since skin cancer is their bread and butter. The concern raised by UV advocates is that “sunphobic propaganda” may do more harm than good, pointing to studies such as this one from Sweden that found that those diagnosed with skin cancer tended to live longer and have less heart attacks and hip fractures. Not surprisingly, the media loved this and ran headlines like “Sunbathers live longer.” Only natural UV exposure was associated with reduced mortality, however; artificial UV exposure, like from tanning beds, was associated with increased mortality. This probably has nothing to do with vitamin D, then. Why then would those who run around outside enough to get skin cancer live longer? Maybe it’s because they’re running around outside. More exercise may explain why they live longer. And here in the United States, more UV exposure was associated with a shorter, not longer, lifespan.

There are modeling studies that suggest that at least 50,000 American cancer deaths may be attributable to low vitamin D levels that could be avoidable with more sunlight exposure that would kill at most 12,000 Americans from skin cancer. So, on balance, the benefits would outweigh the risks—but, again, why accept any risk at all when we can get all the vitamin D we need from supplements? In fact, where did they get those estimates about vitamin D preventing internal cancers? From intervention studies involving giving people vitamin D supplements, not exposing them to UV rays. So, it’s not much of a controversy after all. “In essence, the issue is framed as needing to choose between the lesser of two evils: skin cancer…versus cancer of various internal organs and/or the long list of other ailments” from vitamin D deficiency. The framework ignores the fact that there’s a third way. When we were evolving, we didn’t live long enough to worry about skin cancer, and vitamin “D was not available at the corner store.”

If we just want to look more attractive, how about eating more fruits and vegetables? When high kale models were pitted against high UV models, the golden glow from carotenoid phytonutrients won out, and the same result has been found in Caucasian, Asian, and African American faces. So, may I suggest the produce aisle to get a good healthy tan…gerine?

That’s the gist of what the last 15,950 studies on vitamin D have added to our understanding. Unless something particularly groundbreaking comes out, you can expect the next update in 2021. If you missed the first five videos in this series, see:

I also explore vitamin D as it relates to specific diseases:

The physical attractiveness is from carotenoid deposition in the skin. For more on this, see:

In health,

Michael Greger, M.D.