Are Seed Oils the Problem—or Is It the Context?

I’m fascinated by the seed oil debate for two reasons: (i) the data are complex and often contradictory, and (ii) it’s surprisingly hard to get people to hear what I’m actually saying—rather than what they assume from a headline, thumbnail, hook, or framework of the conversation, such as the identity debate partner sitting across from me.

Deciding whether to reduce the intake of seed oils—or more broadly omega-6 fatty acids—can be confusing, but the right answer for your health is hidden in the nuance. Understanding this debate is the first step to making informed choices that protects your long-term metabolic health.

So today, I’m taking a different approach—one I hope you’ll find original, thought-provoking, and practical.

• First, I’ll start by outlining, in broad strokes, what I believe and what I do.

• Then, we’ll dissect the common arguments against seed oils, and I’ll rate the rigor of each claim.

• Finally, I’ll arm you with question to ask yourself to decide what makes the most sense for your own health and how to better assess such claims and arguments made about health and nutrition more broadly.

At a High Level: My Stance on Seed Oils

In short, I believe seed oils—here defined as highly industrialized and processed oils extracted from plants using “harsh” chemical and heating methods—are unnecessary at best and harmful at worst.

That’s the KISSS ‘keep is super simple stupid’ version. And if you want to leave now, you can’t. But I wouldn’t recommend it.

I personally avoid sunflower, safflower, corn, and canola oil in my diet.

My decision follows the “precautionary principle.”

We still don’t fully understand these industrialized seed oils, but the balance of probability suggests they’re more likely to be harmful than beneficial—at least compared to more natural fat sources such as extra-virgin olive oil, unprocessed nuts and seeds, and, yes, animal-based fats like ghee or tallow.

Now, some of you may be thinking, “Wow, Nick. Way to be anti-climactic.”

But please pause and consider how I said what I said as compared to what is often said.

I am NOT claiming that seed oils are “toxic engine lubricants in a conspiracy by Big Food and the academic elite to keep you sick.” While that may sound like parody, many of you know it’s a fairly accurate summary of a common belief.

My stance is simpler: I’m curious and suspicious.

The evidence on whether—and/or to what extent—seed oils are harmful is unclear, so all else being equal, I choose fats I believe are more likely to be health-positive.

Do you see the distinction?

With that in mind—and with full transparency about my own decisions—let’s take a clear-eyed look at the most common arguments against seed oils.

Arguments Against Seed Oils

Our ancestors didn’t eat this much omega-6 (linoleic acid)

The first “sin of the seed” is its high proportion of omega-6 fat (mostly linoleic acid).

Estimates vary, but our ancestors likely consumed about 2% of their energy from linoleic acid, whereas those in the modern Western world consume closer to 10–12% of calories from omega-6 fat.

This evolutionarily unprecedented rise in omega-6 intake, roughly paralleling an equally unprecedented obesity epidemic, paints a concerning—albeit correlative and circumstantial—picture.

It’s interesting, and it offers fodder for hypothesis generation. But, as many of you know, it’s not sufficient evidence to claim that high omega-6 intake causes obesity or negative health outcomes.

In fact, most evidence suggests that high intake and tissue levels (including adipose tissue levels) of omega-6 fatty acids are linked to positive health outcomes.

Taken alone, I’d give this argument 1.5 out of five stars for rigor.

A high omega-6/omega-3 ratio is inflammatory

If we dig a step deeper, we can consider not just omega-6 levels but also their relationship to their biochemical “fraternal twin,” omega-3. Unlike omega-6, omega-3 fats are generally regarded as beneficial for the heart and brain, and as anti-inflammatory.

While figures vary, an omega-6/omega-3 ratio at or below 4:1 is generally considered “optimal,” whereas those eating a modern Westernized diet tend to have a ratio around 16:1.

The question: Does this cause poor health outcomes?

First, the case for “Yes.”

In humans, it’s difficult to change the omega-6/omega-3 ratio without altering other variables. But in animal models, genetic modifications allow researchers to adjust the ratio while keeping the rest of the diet constant. In such studies, increasing the ratio does appear to worsen health outcomes—compelling evidence, in my view.

However, when we look at humans, the picture gets murkier.

A higher omega-6/omega-3 ratio is indeed associated with worse all-cause mortality (below, left). Case closed? Not quite.

• In one UK Biobank study, a higher ratio correlated with worse all-cause mortality; but higher levels of both omega-6 and omega-3 individually were associated with lower all-cause mortality.

• Even more interesting: the lowest mortality was seen in people with high levels of both omega-3 and omega-6 (below, right).

This is not a mathematical contradiction—it can be reconciled by recognizing that both omega fats may be beneficial overall, but that boosting omega-3 intake is more important. On a population level, a low denominator (omega-3) may be a bigger concern than a high numerator (omega-6).

My take: Beyond a certain threshold, a high omega-6/omega-3 ratio might be enough to cause negative health outcomes. However, this does not justify vilifying omega-6.

• When consumed as part of a mostly whole-foods diet, foods rich in omega-6 are probably not a problem.

• But very high seed-oil intake, combined with low omega-3 intake? Likely harmful—even just considering the omega-6/3 imbalance.

I’d give this argument three out of five stars for rigor. Personally, I aim to keep my omega-6/omega-3 ratio at 4:1 or below.

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Linoleic acid & oxidation susceptibility

Let’s go another level deeper. One concern about linoleic acid is that it’s “fragile” and prone to oxidation, a process that can lead to inflammation and other negative health effects. Linoleic acid can be oxidized either before consumption or after it’s inside the body.

This means the individual’s metabolic status and overall “oxidation environment” may—indeed, likely does—matter.

For example, excess body fat can raise levels of myeloperoxidase (MPO), a marker of oxidative stress and an enzyme that oxidizes fats, including linoleic acid, in tissues and in circulating lipoprotein particles such as LDL.

It’s plausible, then, that in someone with obesity, higher omega-6 intake could cause more metabolic harm (via oxidation inside the body) than it would in a lean, healthy individual.

This raises the interesting possibility that obesity is a “seed oil (omega-6) susceptible” metabolic state.

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A Short Note on 4-Hydroxynoneal (4-HNE)

Now, I’d be remiss not to mention 4-HNE—an aldehyde formed during the oxidation of omega-6 fatty acids. It’s a fascinating yet problematic compound, and one that probably deserves an entire article of its own.

In brief, 4-HNE promotes cell death and metabolic dysfunction and accumulates in a range of chronic diseases, from Alzheimer’s and cardiovascular disease to cancer.

Focusing on cardiovascular disease as an example: 4-HNE can bind to ApoB on LDL particles, encourage foam cell formation, drive inflammation, and ultimately worsen atherosclerosis.

Interestingly, the primary source of 4-HNE is not dietary omega-6 fats but the body’s own internal production. For that reason, I’d prioritize reducing the body’s overall oxidative environment rather than fixating solely on omega-6 intake. Such an approach can still include a diet containing omega-6–rich foods.

But—bottle of industrialized oil to my head—if you were to ask me whether I think a high intake of “seed oils” could exacerbate chronic disease via 4-HNE generated inside or outside the body, I’d need to respond, “yes, it should be one concern.”

And, I’d add, “I think it’s likely a larger concern if you have pre-existing metabolic disease, e.g. obesity.

On balance, I’d give this argument 3.5 out of five stars.

Okay, now we’ve looked at a few anti-seed oil arguments—and how they hold up under scrutiny. But next is where the debate gets truly interesting, and often confusing.

The arguments about industrial processing, ‘toxic’ chemicals, and industry influence are frequently used to provoke fear, but what does the evidence actually say?

And how can you empower yourself to better evaluate those often contradictory health claims?

Seed oils are processed with “toxic” substances

Now we shift gears—away from the fatty acid content of seed oils and toward their additives and extraction methods. Influencers often compile montages of big, scary words to make seed oils sound dangerous: “bleaching,” “deodorizing,” “treated with neurotoxins.”

Let’s call this what it is: an excellent engagement tactic. That doesn’t make it wrong per se—provocative messaging can have value.

But once provoked, where do we go?

In my experience on social media, the stream of substance often runs dry. Once the scaremongering terms are deployed, they’re rarely (if ever) followed by a thorough explanation of how these processes or chemicals translate into actual negative health outcomes for humans, backed by clinical literature and realistic exposure levels from seed oils.

Take hexane as an example.

Hexane is used to extract oil from seeds like soybeans, canola, and sunflower because it efficiently dissolves oil. It’s also used as a solvent in glues, varnishes, and inks, and as a degreasing agent in the printing industry. While subsequent refining steps aim to remove it, trace amounts of hexane can remain in the oil.

It’s true that acute or prolonged exposure to high levels of hexane can damage the nervous system, producing symptoms ranging from nausea and headaches to neuropathies. That sounds alarming.

But can the trace levels found in seed oils actually cause harm?

I’ve never heard of a bona fide case of neuropathy from overconsumption of seed oils. Of course, that might not be a fair threshold for evidence—how would we truly know?

Refined vegetable oils extracted with hexane contain variable amounts of hexane, but rarely if ever high levels. Over the long term, could that be concerning?

Even if acute toxicity is unlikely, could such exposure subtly nudge you health in an unfavorable direction?

My answer: it’s possible.

• And here, I want to distinguish my position from what is often claimed. I’m saying, “I don’t know, but there’s reason for concern, and more research is needed.”

• That is very different from, “Seed oils contain harmful levels of neurotoxins and therefore must be avoided.”

On balance, I’d give this argument three out of five stars.

‘Big Food’ and the ‘academic elite’ want you obese

Two words: incentive structure.

Yes, the food industry wants you to eat more. They do not have your health interests at heart. That’s true. But while it’s a sad reality, it’s not a substantive argument against seed oils.

I could—and perhaps should—end the argument there. But I also have a small chip on my shoulder (fried in tallow, naturally).

In the seed oil debate, and in nutrition discourse more broadly, there’s a tendency to single out entire academic institutions as villains—painting them as if every researcher under their roof holds the same opinion.

This bugs me. Not because I’m brimming with school spirit or wounded pride, but because — frankly — it’s a weak and transparent distraction. By all means, if you disagree with a research finding, dismantle the study. Challenge the specific researchers. Please—go for it.

But skip the brand-bashing for its own sake. Charging at an institution’s name like a bull at a crimson cape might feel satisfying, but—as we Harvardians say—it’s “weak sauce, bro.”

I’d give this argument zero stars.

A mountain of anecdotes

Moving beyond PubMed citations, many people anecdotally report improved health after cutting seed oils from their diet. Reported benefits include better skin, weight loss, and even improved mental health.

I know “anecdote” is often a dirty word among academics. It shouldn’t be.

While I won’t make sweeping generalizations from anecdotes—nor ignore the possibility of causal misattribution—your N = 1 is still your N = 1.

If someone says, “Cutting seed oils from my diet improved my health in X way,” and it turns out—were we to know the objective causal truth—that the improvement actually came from a related dietary change… so what?

Speaking at the individual level, that person is healthier and the heuristic works for them in daily life. I’m happy for them.

From an academic perspective, I’d rate this argument 1.5 out of five stars for “interesting, but not rigorous.” But I’d give it an auxiliary score of four out of five stars for personal actionability. I reserve the final star because you should always question your own perspective.

“But they started it”

Like bickering children, part of the subtext in the seed oil controversy is that other dietary camps have unfairly vilified animal-based fats and foods because they’re high in saturated fat.

Once again, this is not an argument in itself.

If you want to defend steak, butter, and dairy—by all means, do so. I certainly have. But that’s its own exercise. Zero stars.

Now, here are a series of questions I want you to ask yourself when trying to make a personal decision or evaluate claim you might here in the media.

Questions to Ask Yourself

1. What exactly is being claimed—and what is not being claimed?

• Am I responding to the argument or to an exaggerated, assumed version of it?

2. What type of evidence supports this claim?

• Is it observational data, randomized controlled trials, mechanistic studies, animal research, anecdotes, or a mix? How strong is each? And, importantly, what level of evidence can fairly be expected on the topic matter at hand?

3. Does the argument explain how the claimed harm or benefit occurs?

• Or is it simply asserting causation without a plausible biological pathway?

4. Are there credible studies showing the opposite?

• If so, what explains the difference in results—study design, population, dose, or context?

5. What’s my personal context?

• Do I have health conditions, dietary patterns, or lifestyle factors that might make me more—or less—susceptible to the risks or benefits being discussed?

6. What are the trade-offs?

• If I change my diet in this way, what am I adding, removing, or replacing—and how might those shifts affect my overall nutrition?

7. Am I reacting to data, or to the tone and style of how it’s presented?

• Would my conclusion change if the same information came without scare language, dramatic visuals, or brand-bashing?

Seeing Through the Smoke (and Oil)

If you’ve read this far, you’ve probably noticed that my approach to seed oils is less about declaring a final verdict and more about holding the tension between curiosity and evidence.

Some arguments against seed oils crumble under scrutiny; others raise legitimate questions that deserve better answers than the internet’s usual “case closed” proclamations.

The truth is, nutrition science rarely offers perfect clarity—especially on questions shaped by industry influence, evolving methods, and deeply personal health experiences.

Scientific uncertainty isn’t a reason to throw up our hands; it’s a reason to sharpen our thinking.

My own decision to minimize seed oils is not a rallying cry or a purity test.

It’s a personal application of the precautionary principle, informed by the available evidence, my own values, and my ability to make that choice without hardship. Your decision should be shaped the same way—by the facts as you understand them, by your health context, and by the trade-offs you’re willing to make.

So, as you move forward, I invite you to take this same lens beyond seed oils.

Ask better questions. Separate rhetoric from reality. Be willing to hold the uncomfortable space between “we don’t know” and “I must decide.” Because in the end, the goal isn’t to win the debate—it’s to live in a way that supports your health, your clarity, and your long game.

If you liked this article and want more nuanced deep dives into most interesting and cutting-edge metabolic research, give me a Follow. And as always, stay curious.