Health Misinformation | Diet Dogma

I Told You Seed Oils Were Bad For You. Seems I Was Wrong.

Diet dogma is mostly noise. Here’s proof I fell for it too.

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I heard a doctor on a podcast this week say something that stopped me mid-workout. Zero evidence, he said, that seed oils are any more inflammatory than any other oil. Not weak evidence. Not mixed evidence. Zero.

You can hear the episode here

My first reaction was annoyance. My second was to go check if he was full of it.

He wasn’t.

For years I’ve told you, told myself, told anyone who asked, that canola oil and soybean oil and sunflower oil were quietly wrecking people from the inside. Inflammatory. Processed garbage dressed up as food. I believed it without much checking, because it fit everything else I already thought about processed food and I’d read pieces that seemed to back it up.

Here’s the thing. I did check, back when I first started saying this stuff. I read articles, I looked at claims, I felt like I’d done my homework. The problem is I was reading the wrong stack of papers, the ones built on a theory that sounded airtight and never got tested properly. I should have dug past the first layer instead of stopping at the first source that agreed with me.

The theory that sounded right

The case against seed oils goes like this. Seed oils are loaded with linoleic acid, an omega 6 fat. The body can convert linoleic acid into arachidonic acid. Arachidonic acid gets turned into compounds that drive inflammation. So more seed oil in your diet means more inflammation in your body.

Clean logic. Sounds like something a doctor would say with confidence. I said it with confidence.

Except when researchers actually test each link in that chain in real humans, it falls apart.

What the actual research shows

A review of 36 human trials tested whether eating more linoleic acid raises arachidonic acid in the blood. Researchers pushed linoleic acid intake up by as much as 551 percent. Arachidonic acid levels in plasma, blood, and red blood cells did not move in any meaningful way. First link in the chain, broken.

Then there’s the inflammation claim itself, tested directly instead of assumed. A review of 15 randomized controlled trials in healthy adults found no meaningful evidence that dietary linoleic acid raises inflammatory markers. Not “we need more data.” No effect.

A 2026 scoping review set out specifically to check the health claims against seed oils and came back with the opposite of what I’d been saying. The claim that linoleic acid raises inflammation and oxidative stress, and therefore raises heart disease risk, was found to have no foundation in the clinical and observational evidence. The review stated plainly that neither high linoleic acid diets nor seed oil supplementation raise inflammation.

One study measured it directly in people instead of relying on food diaries. Researchers pulled blood markers from nearly 1,900 people and found that higher linoleic acid levels tracked with lower inflammation and better cardiometabolic health, measured from the blood itself rather than from what people remembered eating that week.

I want to be fair here, because I’ve made my living telling you to check sources instead of taking my word for it. There’s a competing argument built on timing. Seed oil consumption rose sharply in the early 1900s, and heart disease deaths climbed one to two decades later, roughly the lag you’d expect for plaque to build in arteries. That’s a real pattern worth noting. It’s also a hundred years of correlation sitting next to smoking rates, sugar consumption, trans fats, and a dozen other things that changed at the same time. A pattern across a century of everything changing is not in the same league as a randomized trial measuring one variable at a time. When I stack the direct trials against the historical correlation, the trials win.

Why I got this wrong

I trusted sources that confirmed something I already believed about processed food, and I stopped digging once I found writing that agreed with me. That’s not research. That’s shopping for a verdict I’d already reached.

I’ve spent years telling you to be skeptical of quick fixes, of supplement hype, of anyone selling a transformation in six weeks. I forgot to point that same skepticism at a belief I liked. Believing something because it confirms what you already think is exactly the failure mode I warn you about in every other part of this newsletter.

The bigger problem

Seed oils are a symptom, not the real issue. The real issue is how much of nutrition advice online runs on certainty that outpaces the evidence. Someone states a claim with total confidence; it spreads because it’s simple and a little scary, and six months later half of you are throwing out your cooking oil based on a theory that never got tested in actual humans.

Diet dogma is mostly noise. Seed oils are bad, seed oils are fine, this is a superfood, that is a toxin—one expert is screaming at another expert on a podcast while you’re standing in the kitchen trying to figure out what to make for dinner. Most of it doesn’t matter nearly as much as the fundamentals, and the fundamentals haven’t changed in the time I’ve been writing this newsletter. Eat enough protein. Lift something heavy on a regular basis. Sleep like it’s your job. Move every day. Eat food that isn’t wrapped in ten layers of packaging most of the time. None of that requires picking a side in a fight about cooking oil.

I’m not telling you to go pour canola oil on everything. I’m telling you the specific claim that seed oils are inflammatory doesn’t hold up against the direct evidence, and I was wrong to state it like it was settled fact. If you’ve been avoiding seed oils because of me, cook with what you like, what fits your budget, and what gets you eating real food instead of takeout. That decision matters a lot less than whether you’re moving your body and getting enough protein today.

I’ll keep getting things wrong sometimes. My job is to correct it when I do, in public, instead of quietly editing an old post and hoping nobody noticed.

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