Is the Risk of Skin Cancer From Sun Exposure Overblown?

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.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Health Benefits of Citrus Zest

New data demonstrating a DNA protective agent present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection or repair of DNA strand breaks.

If not vitamin C, what could the DNA protective agent be? The carotenoid beta-cryptoxanthin, found primarily in citrus, seems to be at least one candidate, as I discuss in my video Citrus Peels and Cancer: Zest for Life? If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA. However, in less than an hour, our DNA repair enzymes can weld most of our DNA back together. What happens if we add some of that citrus phytonutrient? We can effectively double the speed at which DNA is repaired. But, this was determined in a petri dish. What about in a person?

In one study, subjects drank a glass of orange juice and their blood was drawn two hours later. The DNA damage induced with an oxidizing chemical dropped, whereas if they had just had something like orange Kool-Aid instead of orange juice, it didn’t help.

So, do people who eat more fruit walk around with less DNA damage? Yes, particularly women. Does this actually translate into lower cancer rates? It appears so: Citrus alone is associated with a 10 percent reduction in odds of breast cancer.

Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given. So, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange-flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat, not wear, our food. 

Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that “the whole food may be important in modulating DNA repair processes…”

Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. “However, the most striking feature was the protection purported by citrus peel consumption” . Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60 percent increase in risk. So, again, better to stick with the whole fruit. We can eat citrus extra-whole by zesting some of the peel into our dishes.

Now you know why my favorite citrus fruit is kumquat—because you can eat the peel and all!

For other foods that may keep our DNA intact, see my Which Fruits and Vegetables Boost DNA Repair? video. Kiwifruit (Kiwifruit and DNA Repair), broccoli (DNA Protection from Broccoli), and spices (Spicing Up DNA Protection) may also fit the bill.

Interested in learning more about citrus? Check out:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

How to Counteract the Effects of Alcohol

More than a million new cases of skin cancer are diagnosed every year, affecting about one in three Americans in their lifetimes. As I discuss in my video Preventing Skin Cancer from the Inside Out, although the chief risk factor is UV exposure from the sun, alcohol consumption may also play a role. Most of the cancers associated with alcohol use are in the digestive tract, from mouth cancer, throat cancer, and stomach cancer down to cancers of the liver and colon. These involve tissues with which alcohol comes in more direct contact. But why skin cancer?

A study of 300,000 Americans found that excessive drinking was associated with higher rates of sunburn. It “may be that heavy and binge drinking are markers for an underlying willingness to disregard health risks” and pass out on the beach, but it also may be because breakdown products of alcohol in the body generate such massive numbers of free radicals that they eat up the antioxidants that protect our skin from the sun. Plants produce “their own built-in protection against the oxidative damage of the sun,” and we can expropriate these built-in protectors by eating those plants to function as cell protectors within our own bodies. One might say fruit and vegetables provide the best polypharmacy—the best drug store—against the development of cancer.

The ingestion of plant foods increases the antioxidant potential of our bloodstream, which can then be deposited in our tissues to protect us against the damaging effects of the sun’s rays, but only recently was it put to the test.

Researchers studied 20 women and burned their buttock skin with a UV lamp before and after half of them ate three tablespoons of tomato paste a day for three months. There was significantly less DNA damage in the derrieres of those who had been eating the tomatoes. So, three months or even just ten weeks before swimsuit season, if we eat lots of an antioxidant-rich food, such as tomato sauce, we may reduce the redness of a sunburn by 40 percent. It’s like we have built-in sunscreen in our skin. Now, this isn’t as good as a high SPF sunblock, but “[m]uch of the UV exposure over a life time occurs when the skin is not protected; thus, the use of dietary factors with sun-protecting properties might have a substantial beneficial effect.”

It works both ways, though. Alcohol consumption decreases the protection within our skin. If you have people drink about three shots of vodka, within eight minutes—not after ten weeks, but within just eight minutes––the level of carotenoid antioxidants in their skin drops dramatically. If, however, you drink the same amount of vodka in orange juice, there is still a drop in skin antioxidants compared with the initial value, but drinking a screwdriver cocktail is not as bad as drinking vodka neat. Is the difference enough to make a difference out in the sun, though?

After the drinks, researchers exposed volunteers to a UV lamp and waited to see how long it would take them to burn, and the time span until they started turning red was significantly shorter after alcohol consumption than in the experiments in which either no alcohol was consumed or alcohol was consumed in combination with orange juice. It came out to be about an extra half hour out in the sun based solely on what you put in your mouth before heading to the beach. And, oranges are pretty wimpy––not as bad as bananas, but berries have the highest cellular antioxidant activity.

The researchers concluded that “[p]eople should be aware of the fact that the consumption of alcohol in combination with UV light [from sun exposure or a tanning booth] increases their risk of sunburn and therefore their risk of developing premature skin aging and even skin cancer.” If you are going to drink alcohol and be out in the sun, you should make sure you are using sunblock or, at the very least, drinking a strawberry daiquiri or something else to reduce oxidative damage.

Isn’t that wild? Antioxidant dynamics in the body change minute to minute so be sure to keep yourself topped off. See:

What else can tomatoes do? Check out Inhibiting Platelet Activation with Tomato Seeds.

Other videos on skin health include:

Alcohol doesn’t just raise the risk of skin cancer. See Breast Cancer and Alcohol: How Much Is Safe?. But, like the orange juice in a screwdriver cocktail, grape skin components may help mediate wine’s adverse effects. See Breast Cancer Risk: Red Wine vs. White Wine.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: