In my early thirties, I had a spot of skin cancer removed from my back. I was surprised at the diagnosis because I hadn’t sunburned my back since college, but the dermatologist told me skin cancer can show up many years after the sunburn that triggers it. I’ve never had another skin cancer, but I’m scheduled for a just-in-case visit to a dermatologist every 18 months or so.
During my most recent visit, the dermatologist informed me that the recommendation on sunscreen protection has been updated: we’re now supposed to apply SPF 50 sunscreen instead of SPF 35. Kind of like this, I suppose:
I responded to her advice by simply nodding. Truth is, I haven’t worn sunscreen in years. Back in the day, I slathered myself with the stuff because one of Woody Allen’s lines applied to me: “I don’t tan; I stroke.”
But after changing my diet and ditching the frakenfats in favor of real fats, I found I just don’t burn like I once did. I’m now the Bizarro Woody Allen: I don’t stroke; I tan. If I spend four hours doing farm work on a sunny afternoon, my arms and face get a little browner and that’s it. Kind of like this, I suppose:
Seeing how the change in diet changed my skin’s reaction to sunshine got me thinking, of course. Why would the sun be dangerous to humans in the first place? It makes no sense. We didn’t evolve indoors, and we didn’t evolve wearing SPF 50 sunscreen. We need sun on our skin to produce vitamin D naturally.
I also don’t remember skin cancer being a big issue when I was a kid in the 1960s. Out of curiosity, I went looking for information on rates of skin cancer over time. Here’s a quote from an article on sunscreens:
Americans are being diagnosed with melanoma, the deadliest form of skin cancer, at steadily rising rates. According to the National Cancer Institute, the rate of new melanoma cases among American adults has tripled since the 1970s, from 7.9 per 100,000 people, in 1975, to 23 per 100,000, in 2016.
Hmmm … rates of melanoma have tripled since the 1970s, despite all those warnings to slather on the sunscreen. And what else has changed since the 1970s? … let me think for a moment … oh, I’ve got it: we’ve been ditching animals fats in favor of “heart healthy” vegetable oils.
That’s just an association, of course. But it’s one that makes biological sense. The fats you eat become the fats in your skin. If those fats never existed in the human diet and produce inflammation, well, go figure … your skin doesn’t function as it should.
I didn’t exactly find a wealth of literature on diet and skin cancer when I went looking, but what I did find is interesting. Take this study, for example:
Samples of subcutaneous adipose tissue were taken from 100 melanoma patients and 100 matched controls in Sydney in 1984–1985 and were analyzed for constituent fatty acids. The mean percentage of linoleic acid in the triglycerides of the subcutaneous adipose tissue (PLASA T) of these subjects was substantially higher than that in a similar group examined in 1975–1976. In addition, the percentage of polyunsaturated fatty acids was found to be higher in the melanoma patients than in the controls (p < 0.01), and there were significantly more controls than patients who had a low PLASA T (p < 0.01). Relevant literature is quoted and the suggestion is made that increased consumption of dietary polyunsaturates may have a contributory effect in the etiology of melanoma.
Fascinating. Compared to people just nine years earlier, people examined in 1984-1985 had substantially more plant oils in their subcutaneous tissue. (Hooray for “heart healthy” dietary guidelines around the world!) And the real clincher: the melanoma patients had a higher percentage of polyunsaturated fats, leading the researchers to conclude that increased consumption of dietary polyunsaturates may have a contributory effect in the etiology of melanoma.
In other words, eat your margarine and perhaps increase your risk of skin cancer.
There are also studies done on rats and mice, like this one and this one, demonstrating that hydrogenated vegetable fats and diet high in polyunsaturated vegetable fats accelerate the development of skin cancers, while omega-3 fats inhibit the process.
So after personal experience and a bit of research convinced me natural fats are a better protection against skin cancer, I stopped using sunscreen. I didn’t consider it harmful, just unnecessary.
Turns out it may be harmful as well. Here are some quotes from a recent article by Reuters:
The active ingredients of commonly-used sunscreens end up in the bloodstream at much higher levels than current U.S. guidelines from health regulators and warrant further safety studies, according to a small study conducted by U.S. Food and Drug Administration researchers and published on Monday.
The study of 23 volunteers tested four sunscreens, including sprays, lotion and cream, applied to 75 percent of the body four times a day over four days, with blood tests to determine the maximum levels of certain chemicals absorbed into the bloodstream conducted over seven days.
The study found maximum plasma levels of the chemicals it tested for – avobenzone, oxybenzone, octocrylene and in one sunscreen ecamsule – to be well above the level of 0.5 nanograms per milliliter (ng/mL) at which FDA guidelines call for further safety testing.
You know how every time a study demonstrates that statins have nasty side effects, we always see quotes from doctors telling us to continue taking statins because the benefits outweigh the harms, blah-blah-blah? Same thing here:
The results in no way suggest that people should stop using sunscreen to protect against the sun’s harmful ultraviolet (UV) rays, researchers said.
“The demonstration of systemic absorption well above the FDA guideline does not mean these ingredients are unsafe,” Dr. Robert Califf and Dr. Kanade Shinkai said in an editorial that accompanied the study in JAMA.
Okay, maybe there’s nothing unsafe about elevated levels of avobenzone, oxybenzone and octocrylene floating around in your bloodstream. But I’m pretty sure my ancestors didn’t chew on avobenzone plants, so I’d rather not take the chance.
Eat natural fats and get some sun … but if you’re fair-skinned, build up your tolerance over time so you don’t burn. I think that makes more sense than slathering the biggest organ in your body with chemicals that seep into your blood.
And as usual, my thanks to all the previous the USDA Dietary Guidelines Committees for producing dietary advice that ensures doctors of all types – from cardiologists to dermatologists – will never run short of patients.