The Wellness Brew - Issue 23

Avocado oil has become shorthand for the better choice. It's on chips, mayo, dressings, and cooking sprays, usually significantly higher priced than the seed oils it's replacing. A study out of UC Davis says most of those products aren't actually made with it. That's worth unpacking, but so is the question sitting underneath it, which almost nobody is asking: was the upgrade worth it in the first place?

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

A JAMA study has been circulating again, and it's worth knowing what it actually is. Researchers put ten frail nursing home residents, average age 90, through eight weeks of high-intensity resistance training. Strength gains averaged 174%, close to tripling. Midthigh muscle area grew 9% and walking speed improved 48%. The oldest participant was 96. Two caveats: it was published in 1990, so if you saw it presented as new research, it isn't, and with ten participants and no control group it's small by any standard. What makes it hold up is what came next. The same lead author ran a randomized, placebo-controlled trial four years later with 100 frail nursing home residents and found the same result, while nutritional supplements without exercise did nothing for strength or frailty. The takeaway hasn't changed in 36 years. It's rarely too late, and the intervention that worked was resistance training, not gentle chair exercises. — Fiatarone et al., JAMA, 1990.

"The greatest increase in chronic disease in our history"

Former FDA commissioner David Kessler appeared on 60 Minutes Sunday with a blunt read on ultra-processed foods. Kessler ran the FDA in the 1990s and helped expose how tobacco companies manipulated nicotine levels, and he now argues UPFs have "altered our metabolism and have resulted in the greatest increase in chronic disease in our history," naming type 2 diabetes, hypertension, fatty liver, stroke, and heart failure. Asked whether it rivals tobacco, he said the scale is "as large, if not larger," because not everyone smoked but nearly everyone eats this way. Ultra-processed foods account for roughly half the calories in American diets and 60% for children. Kessler has petitioned the FDA to revoke GRAS status for dozens of refined carbohydrates used in these products. Worth noting the industry response: the Consumer Brands Association argues there's no agreed scientific definition of "ultra-processed," which is a real methodological criticism even if it doesn't dissolve the pattern. We covered the underlying evidence in Issue 10. — CBS News, 60 Minutes, August 2026.

Sweeteners aren't as inert as they seem

Cambridge researchers grew gut bacteria in the lab and exposed them to 39 sweeteners — artificial ones like aspartame, saccharin, and sucralose, plant-based ones like stevia and monk fruit, and sugar alcohols like erythritol and xylitol. About three in four changed how at least one type of bacteria grew. They also tested sweeteners alongside things you'd normally consume with them, like caffeine and common medications, and found more than 100 cases where the sweetener acted differently in combination than it did alone. Worth noting: being plant-derived didn't help. Stevia and monk fruit showed effects right alongside the synthetic ones. The caveat is that this is bacteria in a dish, not people, so it shows these compounds do something to gut bacteria rather than proving they make you sick. Still, it's a reason to treat sweeteners as a trade-off rather than a free swap — which is roughly where we landed in Issue 22. — Blasche et al., Molecular Systems Biology, 2026.

If you've swapped to avocado oil in the last few years, you probably did it for a reason. Maybe you wanted out of seed oils. Maybe you'd read that the high smoke point made it better for searing and roasting. Maybe the bag of chips said "made with avocado oil" and that felt like the better choice at the same price.

A study out of UC Davis last month says a lot of us didn't get what we paid for.

Researchers tested 54 processed foods labeled as made with avocado oil. Chips, mayonnaise, salad dressing, bought from online retailers and California stores across 2025 and 2026.

Forty-eight of the 54 were adulterated with cheaper oils, mostly canola and safflower. Broken out by category: 93% of chips, 71% of mayonnaises, and 100% of the salad dressings. [1]

The same team ran the same tests on 20 olive oil products and found only one failure. [1] Their explanation for the gap is straightforward: olive oil has been under regulatory scrutiny for decades, and avocado oil hasn't. International authenticity standards for avocado oil only arrived in late 2024, and enforcement is still thin.

This isn't the first time. A 2020 UC Davis study found 82% of bottled avocado oil was either rancid before its expiration date or cut with other oils. A follow-up found 70% of private-label bottles had the same problem. [2] So the issue runs through the whole supply chain, not just the chip aisle.

Here's the part that stings. The people most affected by all of this are the people who switched to avocado oil specifically to get away from seed oils. They paid a premium to avoid an ingredient, and in most of the products tested, they got it anyway. Sometimes rancid.

Fraud follows money. Avocado oil commands a premium, there were no enforceable standards for most of its boom, and the chemical differences between it and a cheap seed oil are subtle enough to hide outside a lab. That's the same profile that makes honey, spices, and ground coffee perennial targets.

You might reasonably ask whether frying, blending, or emulsifying alters the chemical fingerprints being measured. The researchers accounted for this – they tested that theory directly and found the fatty acids and sterols changed minimally. They also used deliberately conservative thresholds, giving samples room for natural variation from growing region and avocado variety. [1] The failures weren't borderline calls.

Set the fraud aside for a minute, because there's a question underneath it that doesn't get asked much. Is avocado oil actually healthier than alternatives?

The case for avocado oil makes sense. It's high in oleic acid, the same monounsaturated fat that makes up most of olive oil, and monounsaturated fats have a solid evidence base for cardiovascular health. The smoke point is genuinely high. Those two things are the drivers for avocado oil’s explosive growth.

But the evidence is thinner than the rationale behind it. There are no long-term human trials showing that avocado oil reduces cardiovascular events or chronic disease risk. What exists is a good fatty acid profile plus reasoning by analogy to olive oil.

Olive oil is on a different tier. It's been studied in randomized controlled trials on cardiovascular disease, inflammation, metabolic health, and cognition. PREDIMED, one of the largest dietary RCTs ever run, found a Mediterranean diet supplemented with extra virgin olive oil reduced cardiovascular events. [3] A JACC analysis followed more than 90,000 people and linked olive oil intake to lower cardiovascular risk. [4] No other culinary oil comes close to that volume of outcome data.

Part of what makes olive oil so good for you is something avocado oil doesn't have. Extra virgin olive oil (EVOO) is high in polyphenols — hydroxytyrosol, oleocanthal, oleuropein — and a meaningful share of the health benefit gets attributed to these. That peppery bite at the back of your throat from a good EVOO is oleocanthal. Refined avocado oil is engineered to be neutral, which also means stripped of most of its micronutrients.

None of that makes avocado oil a bad fat. It just means it might not be the best.

Looping back to the study, one main reason to buy avocado oil for cooking is the high smoke point. If your bottle is cut with refined canola, the smoke point you paid for isn't there.

Regarding smoke points, there is a nuance that few are aware of. Smoke point is the wrong number to shop by.

What actually matters is oxidative stability, meaning how well a fat resists breaking down into polar compounds and aldehydes when you heat it. Those two properties aren't the same, and they can point in opposite directions.

Take refined canola oil for example. Its smoke point is around 400°F, which looks great on paper. But canola is roughly 28 to 32% polyunsaturated fat, and polyunsaturated fats have multiple double bonds where oxygen can attack. So canola starts breaking down well before it ever smokes, and the longer it's held at heat, the more compounds associated with negative health impacts start to form. 

Saturated fats sit at the other end. No double bonds means nothing for oxygen to grab. Beef tallow runs about 50% saturated, 42% monounsaturated, and only 4% polyunsaturated, which is why it holds up under sustained heat. Ghee is similar once the milk solids are removed.

Extra virgin olive oil is an interesting case, and it's where a common piece of advice gets things backwards. Its smoke point sits slightly below that of seed oils and you've probably heard that heating olive oil destroys it. However, the research paints a different picture. Because it’s high in monounsaturated fat and polyphenols, these actually protect the oil as it heats up and keep it more stable than seed oils at comparable temperatures. 

Polyphenols are antioxidants, which means they protect the oil while it's heating. This is why high-phenolic extra virgin olive oil is more thermally stable than refined olive oil, despite having a lower smoke point. A 2025 study on deep-frying oils at 170 to 210°C found extra virgin olive oils showed lower acidity and less thermal degradation than refined olive oils, sunflower oil, and high-oleic sunflower oil. [7] We’re not suggesting to start deep frying food at home, but it makes the point regarding oil stability at high temps. 

Match the fat to the method rather than looking for one winner.

Extra virgin olive oil is the everyday default. Sautéing, roasting, moderate-heat pan work, and every cold application. It's the only cooking fat with real long-term outcome evidence behind it [3] [4], and the polyphenol loss at normal cooking temperatures is modest. [5]

Tallow or ghee for genuine high heat. Searing a steak, deep frying, anything sustained above 400°F. The stability advantage is real and it isn't marketing.

It’s worth noting that because tallow and ghee are both high in saturated fats, they deserve an extra level of consideration for anyone trying to manage their cholesterol. 

Avocado oil still works as a neutral-flavored high-heat option, with the caveat this entire issue is about. If you buy it, buy from a brand that publishes third-party testing.

A few buying rules that apply across all of this: dark glass over clear, look for a harvest or bottling date rather than just an expiration, buy smaller bottles so they turn over before they oxidize, and learn what rancid smells like. Crayons, old nuts, wet cardboard. Once you've caught it you can't unsmell it.

Back to the study, because each category deserves a different answer. 

Chips. This is the one that matters most. A fried, salted, ultra-processed snack is a fried, salted, ultra-processed snack regardless of which oil is in the fryer. Ninety-three percent of the ones tested weren't even made with what the bag claimed. [1] Paying $7 instead of $3 doesn't convert a chip into a health food, and the label was never the thing making it healthy or not.

Mayonnaise. Seventy-one percent failed, which makes it the best performer in a bad group. Grove’s AvoYeah! was the one brand to pass both series of tests. Similar sentiment as with chips, buy mayo because you want mayo.

Salad dressing. One hundred percent fail rate. Every single product tested. [1] This is also the easiest category to walk away from, because dressing is olive oil, an acid, salt, and something sharp. One of the easiest things to make at home where you control the ingredients. It's cheaper, it tastes better, and it removes the question entirely.

Buy oil in a bottle, not embedded in something else.

The moment oil becomes an ingredient inside a processed product, you lose your visibility and your recourse. You can't smell it, you can't check the harvest date, and you're trusting a supply chain that this study just demonstrated has a problem. That's precisely where the substitution happens.

And the broader takeaway, which outlives this particular study: a label claim is not a health claim. "Made with avocado oil" on a bag of chips is telling you about one ingredient in an ultra-processed food. In most cases it isn't even telling you the truth about that.

Four things you can do this week:

1. A label claim is not a health claim.
"Made with avocado oil" tells you about one ingredient in an ultra-processed food. It doesn't make a chip a health food, and in 93% of the ones tested, it wasn't even true about the ingredient. Apply the same logic to every front-of-package virtue signal you're paying a premium for: organic, grass-fed, gluten-free. The claim describes an input, not the product.

2. Buy oil in a bottle, not baked into something else.
Once oil becomes an ingredient inside a processed product, you have no visibility and no recourse. You can't smell it, you can't check a harvest date, and you're trusting a supply chain this study just showed has a problem. Salad dressing is the easiest place to start — 100% of the tested products failed, and dressing is oil, acid, salt, and something sharp. Ninety seconds with a whisk.

3. Match the fat to the heat.
Extra virgin olive oil for everyday cooking and everything cold, since it's the only cooking fat with real long-term outcome data behind it. Tallow or ghee when you genuinely need sustained high heat. Ignore the smoke point chart — oxidative stability is the property that matters and the two don't track together.

4. Buy oil like it's perishable, because it is.
Dark glass over clear, a harvest or bottling date rather than just an expiration, published third-party testing, and small enough bottles that you finish them before they turn. Learn what rancid smells like — crayons, old nuts, wet cardboard. UC Davis found 82% of bottled avocado oil was rancid or adulterated, and rancidity is the part you can actually detect yourself.

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Wellness, filtered.

The Wellness Brew

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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.