Is Canola Oil Bad For You? The Thing It’s Accused Of Was Bred Out Fifty Years Ago

The case against canola oil is unusually specific, which is what makes it worth checking properly.

It is not a vague wellness vibe. It names a molecule — erucic acid — it names a harm, damage to heart muscle, and it names a regulator. People will tell you the FDA banned the stuff, and you can go and find that they did ban something.

Every part of that is checkable. So we checked it, and the claim comes apart at three separate joints.

Start with what canola actually is, because the name is the clue

Rapeseed oil, the traditional kind, really does contain a lot of erucic acid. In the richest varieties it is 40 to 50% of the oil [2]. And in the 1970s erucic acid was found to cause fatty deposits in the heart muscle of rodents. That is real, and it is why anyone worried in the first place.

So Canadian plant breeders spent that decade breeding it out.

What they produced was a new cultivar, and they named it after exactly what they had done: canola, from Canadian oil, low acid. The word in the bottle is a description of the fix.

The 1989 safety review that accompanied its US approval describes it as a cultivar “selectively bred from old varieties in Canada to be very low in erucic acid” and then states, in four words, “Canola oil is free of those problems” [1]. The FDA granted it GRAS status — generally recognised as safe.

That paper also gives the composition, which is worth knowing: 55% oleic acid, 25% linoleic, 10% alpha-linolenic, and only 4% saturated fat [1].

The FDA really did ban something. It wasn’t this.

Here is where the claim gets its air of verifiability, and it is the most interesting step in the whole chain.

The FDA did ban an oil for cooking on the strength of the erucic acid rodent data. It banned mustard oil — a different oil, high in erucic acid, popular in South Asia [7]. That ban is real and still stands.

So when someone tells you the FDA banned the oil because of erucic acid, they are describing a genuine regulatory action. They have just attached it to the wrong bottle.

And the ban itself turns out to be contested. Australia, New Zealand and the 27 EU countries set upper limits for mustard oil rather than banning it. India’s Lipid Association recommends it as heart-healthy. The clinical lipidology review that lays this out counts 29 countries permitting limited amounts and calls for a fresh FDA review of the erucic acid safety limits [7].

The same paper lists canola first among the “healthier oils” it recommends instead [7].

Now the part that surprised us: the rats may not have been poisoned by erucic acid either

We went back to the animal work, expecting to write a paragraph saying “rodent hearts are not human hearts” and move on. That is not what is in there.

Somebody ran the obvious control. If erucic acid causes the heart lesions, then feeding rats erucic acid should cause them, and feeding rats rapeseed oil should cause them to the same degree at the same tissue levels.

So they compared rats fed 20% rapeseed oil against rats fed lard with 5.4% free erucic acid added. The erucic acid ended up in their hearts at no significantly different level. But “the incidence and severity of cardiac lesions were significantly higher in rapeseed oil-fed rats” [2].

The review’s summary of that result: the lesions “are not related to the content of erucic acid per se” [2]. The researchers suggested something else about the oil was responsible.

Read that again, because it is the strangest thing on this page. The molecule that gave canola its bad name may not have caused the damage it is named for — in the rats, in the experiment, at the time.

A separate animal study fed 8.9% erucic acid and found no loss of heart contractile capacity, no fibrotic lesions and no ECG changes at all [2].

What about humans? Two studies, and they disagree

This is where a lazier version of this article would stop and declare victory. We are not going to, because the second study is inconvenient and it is not in the review’s abstract. You only find it by reading the paper.

The first: ten people in Sichuan province, China, who regularly consumed half a litre a month of mustard seed or rapeseed oil rich in erucic acid. No correlation was found between that very high intake and degenerative cardiomyopathy [2]. Ten people is not much, but they are ten people at the exposure that is supposed to do the damage.

The second: two large American cohorts — 3,694 older adults in the Cardiovascular Health Study and 3,577 middle-aged adults in the Atherosclerosis Risk in Communities study. Higher erucic acid in plasma was associated with more congestive heart failure in both, with hazard ratios running from 1.34 to 1.92 [2].

That is a real signal in a lot of people and we are not going to bury it.

Two things about it, though. The authors themselves say the effect “may result from the presence of other long-chain monounsaturated fatty acids” travelling alongside it in the blood [2]. And — this is the important one — it measured erucic acid in blood, not canola oil in diet. Nobody in those cohorts was assigned to eat anything.

If that sounds familiar, it is because it is the same problem we took apart on erythritol and again on seed oils: a molecule measured in blood is not the same as a food measured on a plate, and a marker of something can ride along with a disease without causing it. Third time on this site, different field each time.

Meanwhile, erucic acid is in your salmon

One more thing about the molecule before we leave it. It is not exotic and it is not confined to Brassicas.

Nobody is running a campaign against salmon. Europe’s food safety authority handles erucic acid the way it handles most things — with a tolerable daily intake, set at 7 mg per kilogram of body weight [2]. A threshold, not a prohibition.

So what does canola actually do when you eat it?

All of the above is about a molecule that was bred out. The better question is what the oil on the shelf does in trials, and there are a lot of them.

A systematic review pooled 42 studies. Against other cooking oils, canola lowered total cholesterol, LDL cholesterol, the LDL-to-HDL ratio and apolipoprotein B — the protein that tags the particles most implicated in artery disease [3]. Against saturated fats the gap was much wider still.

And then the finding we did not expect.

Thirteen randomised trials have compared canola directly against olive oil — the oil with the health halo, the one nobody has to defend. Pooled, canola lowered LDL cholesterol by 6.13 mg/dL more than olive oil did (95% confidence interval 9.79 to 2.46 lower, p = 0.001), and total cholesterol by 8.92 mg/dL more [4].

There was no difference on HDL, triglycerides or VLDL [4] — so this is a specific win on one set of numbers, not a rout. But it is a win, and it belongs to the bottle with the industrial-lubricant reputation.

A network meta-analysis makes the same point from a different angle. It took 54 trials and ranked thirteen fats — from safflower to lard to butter — against each other. Rapeseed came second of thirteen for lowering LDL and second for total cholesterol, behind safflower oil [5].

For what it is worth in the other direction, coconut oil ranked top for raising HDL, and every oil tested beat butter on LDL [5].

The sentence we are obliged to write

Everything in that last section is about cholesterol. It is not about whether you live longer.

We published a verdict on seed oils the same day as this one, and the most uncomfortable thing in it is that when researchers actually ran the trial — replacing saturated fat with vegetable oil, in thousands of people, with all the meals provided — cholesterol dropped exactly as designed and nobody was saved.

So we are not going to turn round a day later and tell you canola lowers LDL therefore canola extends your life. No trial has ever tested a specific cooking oil against death and produced a clean answer. Anyone who tells you otherwise about any oil, in either direction, is selling you something.

What we can say is narrower and still useful: the specific accusation against canola does not survive contact with the evidence.

On weight, incidentally, the honest answer is “barely.” A meta-analysis of 25 studies found canola reduced body weight by 0.30 kg — about two thirds of a pound — and had no significant effect on BMI, waist, hips, lean mass or fat mass [6]. That is not a weight loss strategy, and we are including it because it is unimpressive.

What we are rating

Unsupported: the claim that canola oil harms you because it is rapeseed and contains erucic acid. The erucic acid was bred out before the oil was sold in America. Even in the rat studies, the lesions were judged not to be caused by erucic acid itself. The FDA action people cite was taken against a different oil. And the human evidence on erucic acid at high intake found nothing.

Reported but not resolved: the plasma erucic acid and heart failure association across two cohorts, which we have shown you rather than skipped, and which measures blood rather than diet.

Not claimed: that canola makes you healthier or live longer. It improves cholesterol numbers in trials. That is a different, smaller statement, and our own seed oils page explains why the gap between the two matters.

What to actually do

Cook with whatever you like from the unsaturated shelf. Canola, olive, sunflower, safflower — on blood lipids they are all clustered near each other and all clearly ahead of butter [5]. The differences between them are smaller than the difference between any of them and the thing they replace.

Do not pay a premium to avoid canola specifically. “Canola-free” is a price tag attached to a molecule that was removed from the crop in the 1970s.

If you like olive oil, keep using olive oil. Nothing here is an argument against it — it has more going for it than its LDL number, and the difference measured was 6 mg/dL, not a chasm.

And judge the meal, not the bottle. Most cooking oil reaches people inside fried and packaged food, which is where the stronger evidence against a modern diet actually sits. We make the same point about seed oils generally and about canned fish.

This is journalism, not medical advice. If you are managing cholesterol or heart disease with a clinician, that is the conversation that should decide what is in your kitchen.