Revisiting Sunscreen

Mother applying sun protection sunscreen on her baby girl's face.For the last 30 years, the messaging has been clear: Slather your body with sunscreen if you so much as even think about going outside in the sun. Cloudy and rainy? Doesn’t matter. Wear the sunscreen. Want to build up a base tan? You’re killing yourself. Wear the sunscreen. It’s only ten minutes? That ten minutes of sunscreen-less sun exposure will shave a year off your life. Wear the sunscreen.

In more recent years, the tide has shifted. Research has come out showing that most commercial sunscreen contains chemical compounds that act as carcinogens when absorbed, at least in animal models. Maybe we don’t even want to block the sun at all. Or maybe we do, but there’s a better way to do it than using chemical filters that absorb into our skin. At any rate, I figured with summer rolling around that it was time to revisit the topic of sunscreen. So let’s do that, shall we?

What’s Wrong with Sunscreen?

Most sunscreens have a lot wrong with them:

  • Endocrine disrupting UV filters
  • Imbalanced UV protection
  • Parabens
  • Retinyl Palmitate

Endocrine Disrupting UV Filters

Most of your typical commercial sunscreens use chemical UV-filters like benzophenone and oxybenzone that in addition to blocking UV possess a hidden feature: endocrine disruption. Certain forms of benzophenone, for example, inhibit the action of thyroid peroxidase, an enzyme necessary for the production of thyroid hormone.1 Another study showed that application of sunscreen containing benzophenone-2 for five days lowered T4 and T3 thyroid hormones in rats.2 Later, researchers examined the estrogenic effects of another UV-filter used in sunscreen called octyl-methoxycinnamate and found that typical amounts were enough to disrupt hormonal function and exert other, non-endocrine health effects when applied to rat skin.3 That might not a problem if UV-filters in sunscreen weren’t designed to be absorbed into the skin, and therefore the body, nor if every expert weren’t telling us to slather a quarter cup full all over our bodies at the first hint of sunlight. But additional ingredients in the sunblock enhance dermal absorption of these compounds.

It’s also worth mentioning that UV-filtering chemicals often have even more drastic effects on wildlife, like the zebrafish, in whom low amounts of oxybenzone exert multigenerational effects at the gene transcription level.4

The worst part is that even effective against the development of melanoma! In fact, one study found a positive association between sunscreen usage and melanoma incidence.5


Imbalanced UV Protection

Most sunscreens block UVB only; that’s what SPF refers to—the ability of the sunscreen to block UVB. But our skin is designed to deal with UVB and UVA in concert. After all, UVB with UVA is the ancestral environment. You need both.

UVB rays are the triggers for vitamin D production in our bodies. UVB rays penetrate the epidermis, the upper layers of our skin. UVA rays, on the other hand, penetrate more deeply into the basal section of the dermis, which is where most skin cancer develops. Excessive UVA exposure also associates with wrinkling, immune suppression, oxidative stress, and related aging. Research shows that concurrent exposure to UVB actually serves to counteract skin damage and inflammation from UVA. We need both together. Blocking one while exposing our skin to the other is a recipe for danger.


Although parabens are sometimes used as food preservatives, they’re also used as preservatives in sunscreens—and the majority of urinary parabens derives from nondietary sources like cosmetics, primarily, where they are used to extend shelf life.6 They show up in our urine because humans can readily absorb parabens from topical application.7 Although the health effects haven’t been explicitly proven, human studies suggest a link between urinary paraben levels and certain health conditions, such as sensitivities to airborne and food allergies, elevated stress hormones in pregnant mothers and their newborn children (who, by the way, are showing up with parabens in their first urine!), and DNA damage to sperm.8910

Retinyl Palmitate

Vitamin A in the diet is protective against sun damage, so manufacturers figured they’d start putting it in topical sunscreens. Except a 2012 study in hairless mice found that applying retinyl palmitate to the bare skin and exposing it to UV increased tumor incidence and skin damage. Now, humans aren’t hairless mice. We are wild animals and the hairless mouse has been bred specifically for laboratory experiments. It’s likely that the hairless mouse is more sensitive to skin irritants, and the results from the 2012 paper may not apply to us.

But even if retinyl palmitate isn’t carcinogenic, it’s useless. Avoid just to be safe.

What Are Healthy Sunscreens?

But just because conventional sunscreens are toxic and likely carcinogenic doesn’t mean the sun can’t damage your skin. It can. You still need protection.

There are a few types of sunscreens I do endorse.

Zinc Oxide

Rather than a chemical barrier, zinc oxide is a physical barrier. It sits on your skin, physically preventing UV from damaging you. Zinc oxide is broad spectrum, meaning it blocks both UVA and UVB. Zinc oxide does not absorb into the skin, which is why it stays white (this is also why I can’t fully endorse nano zinc oxide sunscreens that do absorb into the skin) and it’s why most people avoid them—they think the white is unsightly.

It’s not pretty but boy does it work.

Edible Sunscreen

Eating colorful plants and animal foods is a form of “edible sunscreen.” For instance, a high-carotenoid diet protects the skin against UV damage, and lycopene, the active constituent in tomatoes (more active eaten with fat and cooked), has similar effects.11 Polyphenols in general tend to increase the skin’s antioxidant capacity. Anthocyanins, found in red wine and berries, also may also be useful. Consumption of both coffee and green tea have been shown to increase UV-protection, probably due to both the caffeine content and the phytochemicals present in tea and coffee.1213

Berries, red wine, cooked tomatoes (tomato sauce, paste, ketchup), carrots, paprika, pastured egg yolks, sockeye salmon, shrimp, green tea, and coffee form the basis of a good sun-resistance protocol. Supplementary lutein, zeaxanthin, and astaxanthin can also help.

Infrared Light

IR radiation, as seen in morning sunrises, evening sunsets, infrared saunas, and red light devices, increases the skin’s resistance to UV exposure. This protective effect of infrared light lasts for 24 hours.

Good Sleep and a Healthy Circadian Rhythm

Like almost every other physiological tool we employ, our ability to repair UV-derived damage depends on a well-functioning circadian rhythm.14 If you didn’t sleep well or are running on a chronic sleep deficit, you may want to hold off on the sunbathing until you get your sleep in order as your skin won’t recover as well.

Plus, melatonin itself is photoprotective against UV damage, and human skin cells synthesize it in-house.15


Physically blocking UV light from hitting your skin with hats, clothing, and umbrellas is the oldest form of sunscreen around. If you’re going to spend an extended day in the sun, I highly recommend having some shade handy. The pop up “day-tents” are great for long beach days.

Smart Time-in-the-sun Management

The safest time to get sun is actually at noon. That’s when UVB exposure, and thus vitamin D production, is at its peak (PDF). UVB burns, but it also tans (thus giving warning), and it doesn’t penetrate deep enough into the epidermis to trigger melanoma. At noon, you’re getting both UVB and UVA. UVB also counteracts the UVA damage; UVA keeps the vitamin D synthesis from getting out of hand. If we upset the balance and get too much UVA without enough UVB, melanoma may result.16

However, you also need to limit your time in the sun. Noon sun is potent but powerful. You may need as little as 10 minutes to get the full dose of vitamin D, depending on your skin color and baseline resistance to UV. Don’t burn. Don’t get pink. Don’t wait til your skin gets tight and stiff.

And you need to be consistent: going on a vacation to the tropics a couple times a year and getting almost zero sun the rest of the year is not how you do it. Small daily doses of sun exposure are healthiest; intermittent doses are the most dangerous.

As you can see, the healthiest ways to screen out sun have little to do with slathering yourself with lotion. If you’re going to forego traditional sunscreen—and I recommend that you do—you have to apply a much more rigorous, holistic, full-spectrum “sunscreen” to your entire life.

How do you do sunscreen? What do you use? What do you do instead?

TAGS:  sun

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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