The Wellness Brew - Issue 20

Sunscreen is one of the most polarized topics in wellness. Some people apply SPF every morning like they are brushing their teeth. Others avoid sunscreen entirely because of concerns about chemical UV filters and endocrine disruption. The honest answer is somewhere in between, and this week's Deep Dive walks through what the evidence supports on chemical vs. mineral sunscreens, sun exposure, and how to think about the practical decisions.

But first, we filtered the noise — here's what's worth knowing this week.

Transglutaminase, commonly called "meat glue," is an enzyme used by food manufacturers to bind smaller pieces of meat into larger cuts. It is what turns scraps into what looks like a solid filet, and it is legal in the US. The USDA does require any product using it to be labeled as "formed" or "reformed" meat with the ingredient listed as "TG enzyme," "enzyme," or "TGP enzyme." The primary safety concern is bacterial contamination. When multiple pieces of meat are bonded together, bacteria that would normally live on the surface get trapped inside the product, which increases the risk of foodborne illness if the meat is not cooked thoroughly. Meat glue is banned by Russia and the EU restricted thrombin-based versions in 2010, though the microbial version remains legal in most countries. The practical takeaway: check meat labels for "formed" or "reformed," and if you see the "TG enzyme" ingredient, know what you are buying. Whole cuts from a butcher you trust are the cleaner path. — Reader's Digest, The Gross Ingredient You're Probably Eating, 2025.

A peer-reviewed EWG study published in Environmental Research estimated that nitrate contamination in US drinking water may be responsible for up to 12,594 cases of cancer annually, with associated healthcare costs of up to $1.5 billion. Four-fifths of those estimated cases are colorectal cancer, which has been rising rapidly in younger adults over the past two decades. The contamination comes primarily from agricultural runoff of fertilizer and manure into rivers, lakes, and streams. The EPA's legal limit for nitrate in drinking water is 10 parts per million, set in 1962 to protect infants from blue baby syndrome. But peer-reviewed studies have linked elevated cancer risk at levels below 5 ppm, half the current legal limit. More than 1,600 US community water systems test consistently above that threshold. The practical takeaway is straightforward: filter your tap water. Reverse osmosis is the gold standard for nitrate removal. Carbon-block filters do not remove nitrate reliably. Check your utility's water quality report or look up your zip code in EWG's Tap Water Database. — Temkin et al., Environmental Research, 2019.

A blood test can now predict Alzheimer's risk a decade before symptoms

A study published in JAMA on July 14, 2026, and presented at the Alzheimer's Association International Conference in London, found that a blood test measuring p-tau217 (a protein linked to Alzheimer's) can predict cognitive impairment in symptom-free older adults up to 10 years before dementia develops. Cognitively healthy adults with very high p-tau217 levels had a 78 percent risk of developing cognitive impairment within 10 years and a 33 percent risk within five years. Prior research suggests p-tau217 begins accumulating 10 to 20 years before Alzheimer's symptoms appear. The test is already used clinically to help diagnose Alzheimer's in patients with cognitive concerns, but the new research establishes its predictive power in people who feel completely normal today. For anyone with a family history of Alzheimer's or concerns about long-term brain health, this test may be worth knowing about and discussing with your doctor. The value of early detection is not just diagnostic but strategic. It gives you 10 to 20 years to actually do something about it. — Buckley et al., JAMA, July 2026.

A quick note before we start – my wife is a dermatologist and we’ve had many discussions on this topic over the years. She did not participate in this article and these views are my own. Where I land on sunscreen and sun exposure is based on my own interpretation of the evidence.

Sunscreen is one of the most polarized topics in wellness. Two camps dominate the conversation. On one side, the reflexively pro-sunscreen position: any sun exposure without SPF is dangerous, wear sunscreen every day, on every exposed area, year-round. On the other side, the reflexively anti-sunscreen position: chemical sunscreens are toxic endocrine disruptors, skin cancer is caused by seed oils and inflammation, go bare in the sun. This is the position that dominates parts of wellness and health influencer culture.

Neither camp is fully right. Chemical sunscreens do have documented endocrine concerns and are systemically absorbed. Sun exposure does produce vitamin D and is associated with lower mortality when regular and moderate. Burning does cause skin cancer. Mineral sunscreens are meaningfully cleaner than chemical ones. All of these are true simultaneously.

Three concerns are worth understanding, in order of how well-established they are.

Systemic absorption is now confirmed. A 2020 FDA study published in JAMA tested six common chemical UV filters: oxybenzone, avobenzone, octocrylene, homosalate, octisalate, and octinoxate. With even a single full-body application, all six were absorbed into the bloodstream at levels exceeding the FDA's 0.5 ng/mL safety threshold.[1] Oxybenzone reached the highest concentrations, sometimes hundreds of times the threshold. The FDA now says further data is needed to determine whether these ingredients can be considered safe at typical use.

Oxybenzone is now detected in nearly every American. CDC NHANES biomonitoring data has consistently found oxybenzone (or its metabolite BP-3) in the urine of approximately 97 percent of Americans. This is universal exposure. In addition to sunscreen, chemical UV filters also appear in lipsticks, moisturizers, hair sprays, and other consumer products.

The endocrine disruption evidence is meaningful but not fully settled. Multiple systematic reviews, including a 2025 review covering 254 studies, have concluded that oxybenzone has estrogenic and anti-androgenic activity in laboratory and animal models.[2] The 2025 review flagged concerns about developmental effects, pubertal outcomes, and reproductive harm. Human studies have not conclusively demonstrated harm at typical exposure levels, but the accumulated evidence has been enough that regulatory bodies globally are increasingly restrictive. Hawaii banned oxybenzone and octinoxate in 2018 and the EU has restricted several chemical UV filters. 

The honest position: the risk is not zero, and the evidence is directionally clear even if not fully conclusive. When cleaner alternatives exist and work, choosing chemical sunscreens as your default is the harder position to defend.

The reflexive pro-sunscreen advice also has real gaps.

Sun exposure produces vitamin D. Ten to fifteen minutes of midday summer sun on arms and legs produces roughly the vitamin D equivalent of a 10,000 IU supplement in fair-skinned individuals. Vitamin D deficiency is genuinely widespread in North America, particularly at higher latitudes, and is associated with elevated cardiovascular disease risk, immune dysfunction, and multiple cancers.

Regular moderate sun exposure is associated with lower mortality. A 2016 Swedish cohort study of nearly 30,000 women followed for 20 years found that sun-avoidant women had mortality rates similar to smokers, while women with the highest sun exposure lived meaningfully longer than those with the lowest.[3] Vitamin D was part of the explanation but not the whole one. Sun exposure appears to have benefits beyond vitamin D synthesis, including improved cardiovascular function and nitric oxide release.

Burning is the specific risk, not sun exposure itself. Melanoma is more strongly associated with intense, intermittent sun exposure (sunburns, particularly in childhood and adolescence) than with cumulative moderate exposure. The reflexive "always wear SPF every day" advice conflates two different risks. Preventing sunburn is genuinely important. Avoiding all sun exposure is not.

The honest position: sensible sun exposure is beneficial. Burning is not. Complete sun avoidance is not the answer and is not fully supported by the evidence.

Once you accept that both camps are half right, the practical answer is straightforward.

Default to mineral sunscreen. Zinc oxide and titanium dioxide sit on the surface of the skin. They are not systemically absorbed. They provide broad-spectrum UVA and UVB protection. They are safe for children, pregnant women, and coral reefs. They are the default answer for any regular sunscreen use.

Mineral sunscreens can leave a white tint, but modern formulations have improved dramatically. 

Brand recommendations: Four brands are worth calling out.

Physical barriers are more reliable than any sunscreen. Long sleeves, wide-brimmed hats, and shade provide consistent protection that does not require reapplication and does not carry chemistry concerns. UPF-rated clothing is now widely available in lightweight, breathable fabrics. For extended outdoor time (long hikes, days at the beach, an afternoon in the yard), a UPF shirt and a hat cover more skin more reliably than sunscreen on the same areas. This is the single most underrated part of sun protection.

One honest exception on chemical sunscreens. For people who almost never use sunscreen and find themselves in a situation where the only option is a chemical formulation, using it is meaningfully better than burning. The endocrine concerns with chemical UV filters are about chronic and repeated exposure, not a single application at a wedding or on an unexpected beach day. If the choice is between a chemical sunscreen you have on hand and a bad sunburn, use the sunscreen. The occasional use is not the problem. The daily default is.

Worth briefly flagging. The FDA recently approved bemotrizinol (BEMT) as the first new sunscreen active ingredient in over 20 years.[4] BEMT has been used in Europe and Asia for more than 25 years. It provides broad-spectrum protection, is not meaningfully systemically absorbed, and is significantly more photostable than avobenzone.

For readers who have struggled with mineral sunscreens because of the white cast and cannot find a formulation they will actually wear consistently, BEMT-based products will be a genuinely cleaner chemical option once they reach US shelves. Neutrogena and La Roche-Posay are among the brands developing BEMT-based products for the US market. 

The Compounding Investment

Sun exposure and sunscreen decisions compound like everything else. The choices you make in your 30s and 40s about which products you use, how much daily sun you get, and whether you burn or protect define your risk profile for decades.

The good news is that the practical framework is simple. Mineral sunscreen when you need it. Physical barriers when you can. Chemical sunscreens only in rare cases when the alternative is a burn. Sensible sun exposure without burning. That covers 95 percent of what the evidence supports.

Three things you can do this week:

1. Switch to mineral sunscreen as your default.
Zinc oxide or titanium dioxide as the active ingredient. Blue Lizard, Badger, Babo Botanicals and Freaks of Nature are all safe and widely available. Yes, they leave a subtle white tint. The trade is worth making, especially for kids and for anyone daily-applying to large surface areas of skin.

2. Use physical barriers whenever you can.
Long sleeves, wide-brimmed hats, and shade provide more reliable protection than any sunscreen and do not carry chemistry concerns. For extended outdoor time, a UPF shirt and a hat cover more skin more consistently than sunscreen on the same areas. This is the most underrated part of sun protection.

3. Get 10 to 20 minutes of unprotected sun exposure most days during warmer months.
Arms and legs, midday hours. Enough to produce meaningful vitamin D without approaching burn thresholds for most people. After that window, cover up or apply mineral sunscreen. The reflexive "SPF every day, year-round" advice is not the best answer for most people.

If you found this useful, please forward it to your friends and family. If you had this forwarded to you — sign up here.

Wellness, filtered.

The Wellness Brew

Sources:

Disclaimer: The Wellness Brew is for informational purposes only and does not constitute medical advice. The content published here is not intended to diagnose, treat, cure, or prevent any disease or health condition. Always consult a qualified healthcare professional before making any changes to your diet, supplement routine, or lifestyle.