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:

We Have Specific Fruit and Vegetable Receptors

According to a recent survey, the number of Americans adults who say they are eating ‘pretty much whatever they want’ is at an all-time high,” which unfortunately includes “too few fruits and vegetables,” as well as “too little variety.” Half of all fruit servings are taken up by just six foods: orange juice, bananas, apple juice, apples, grapes, and watermelons. Only five foods—iceberg lettuce, frozen potatoes, fresh potatoes, potato chips, and canned tomatoes—make up half of all vegetable servings. We’re not only eating too few fruits and veggies. We’re also missing out on the healthiest fruits, which are berries, and the healthiest vegetables, which are dark green leafies. The fruit and vegetable palette for our palate is sadly lacking.

Why does dietary diversity matter? As I discuss in my video Specific Receptors for Specific Fruits and Vegetables, different foods may affect different problems. Cabbage, cauliflower, broccoli, and Brussels sprouts are associated with lower risk of colon cancer in the middle and right side of our body, whereas risk of colon cancer further down on the left side of our body appears to be better lowered by carrots, pumpkins, and apples. So, “different F/V [fruits and vegetables] may confer different risks for cancer” of different parts of even the same organ.

Variety is the spice of life—and may prolong it. “Independent from quantity of consumption, variety in fruit and vegetable consumption may decrease lung cancer risk,” meaning if two people eat the same number of fruits and vegetables, the one eating a greater variety may be at lower risk.

It’s not just cancer risk. In a study of thousands of men and women, a greater quantity of vegetables and a greater variety may independently be beneficial for reducing the risk of type 2 diabetes. Even after removing the effects of quantity, “each different additional two item per week increase in variety of F&V [fruit and vegetable] intake was associated with an 8% reduction in the incidence of T2D [type 2 diabetes].” Why? Well, it “may be attributable to individual or combined effects of the many different bioactive phytochemicals contained in F&V. Thus, consumption of a wide variety of F&V will increase the likelihood of consuming” more of them.

“All the vegetables may offer protection…against chronic diseases,” but “[e]ach vegetable group contains a unique combination and amount of these [phytonutrients], which distinguishes them from other groups and vegetables within their own group.” Indeed, because “each vegetable contains a unique combination of phytonutriceuticals (vitamins, minerals, dietary fiber and phytochemicals), a great diversity of vegetables should be eaten…to get all the health benefits.”

Does it matter, though, if we get alpha-carotene or beta-carotene? Isn’t an antioxidant an antioxidant? No. “It has been shown that phytochemicals bind to specific receptors and proteins” in our bodies. For example, our body appears to have a green tea receptor—that is, a receptor for EGCG, which is a key component of green tea. There are binding proteins for the phytonutrients in grapes, onions, and capers. In my video The Broccoli Receptor: Our First Line of Defense, I talk about the broccoli receptor, for instance. Recently, a cell surface receptor was identified for a nutrient concentrated in apple peels. Importantly, these target proteins are considered indispensable for these plants foods to do what they do, but they can only do it if we actually eat them.

Just like it’s better to eat a whole orange than simply take a vitamin C pill, because, otherwise, we’d miss out on all the other wonderful things in oranges that aren’t in the pill, by just eating an apple, we’re also missing out on all the wonderful things in oranges. When it comes to the unique phytonutrient profile of each fruit and vegetable, it truly is like comparing apples to oranges.

This is one of the reasons I developed my Daily Dozen checklist of foods to incorporate into one’s routine. Download the free iPhone and Android apps, and be sure to watch my video Dr. Greger’s Daily Dozen Checklist.

I discuss how produce variety—not just quality and quantity—may be important in Apples and Oranges: Dietary Diversity and Garden Variety Anti-Inflammation, so I hope you’ll check them out. You can also learn more about why combining certain foods together may be more beneficial than eating them separately in Food Synergy.

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: