Is Vegetable Oil Bad For You? It Was — And That Part Has Been Banned

It was. Genuinely, measurably, and for decades.

And the part that was doing the damage has been taken out, which is why this page reaches a different answer from the one you might expect.

What is vegetable oil actually made from?

Start with the strangest thing about the bottle: it does not say.

“Vegetable oil” is a labelling term, not a plant. It is a category that a manufacturer can fill with soybean, corn, sunflower, cottonseed, or a blend, and the label satisfies the requirement either way.

In practice, in America, it is mostly soy. An analysis tracing 373 food commodities through the US food supply from 1909 to 1999 attributes the rise in linoleic acid “primarily to soybean oil” [1].

So when someone tells you to avoid vegetable oil, they are mostly telling you to avoid soybean oil, and the bottle is not going to help you work that out.

Is vegetable oil the same as canola oil?

No, and it is a fair question because the bottles sit next to each other and cost about the same.

Canola is a specific crop. It is rapeseed, bred in Canada to be very low in erucic acid, and a bottle labelled canola contains that and nothing else. “Vegetable oil” is a category that usually means soybean and legally need not.

Their fatty acid make-up differs too — canola is higher in monounsaturated fat and carries some omega-3, soybean is higher in linoleic acid. We took canola apart separately in is canola oil bad for you, where the short version is that the thing it is accused of was bred out of the crop fifty years ago.

The exposure really did change, enormously

Before getting to whether it matters, it is worth being straight about the scale of what happened, because it is the part the sceptics underplay.

Between 1909 and 1999, estimated per capita consumption of soybean oil in the United States rose more than a thousandfold [1]. Linoleic acid went from 2.79% of calories to 7.21%. The ratio of omega-6 to omega-3 went from 6.4 to 10.

That is a change in the food supply with very few parallels. And it did not stay in the food supply: the linoleic acid stored in Americans’ body fat has risen 136% over half a century, closely tracking intake [3]. Body fat is a slow, honest record of a long-term diet, and it agrees.

One caveat on that thousandfold figure, since we would want it applied to anyone else’s numbers: it comes from disappearance data — how much oil entered the food supply per head — not from watching people eat [1]. It measures supply, and supply overstates intake.

Are hydrogenated oils bad for you?

Here is the part of the story that is unambiguously true, and it is the reason the fear exists at all.

Liquid oil is inconvenient for industry. It does not make a solid margarine, it does not give pastry the right texture, and it goes rancid. So the oil was partially hydrogenated — hydrogen forced into it to make it solid and stable.

That process created industrial trans fat. Not the plant, not the seed, not the linoleic acid. The processing.

And trans fat did what the current fears only allege. We know because somebody got to run the experiment: between 2007 and 2011, eleven New York counties restricted trans fats while others did not, and researchers compared them [2].

Three or more years after the restrictions, the counties that had banned trans fats saw heart attacks and strokes fall an additional 6.2% beyond the trend everywhere else — and heart attacks alone 7.8% [2]. Eight point four million adults in the restricted counties against 3.3 million in matched comparison counties, with the comparison counties chosen for similar urbanicity.

Being straight about it: the stroke number on its own was not statistically significant (−3.6%, P = 0.08) [2]. The combined result is carried by heart attacks.

Still — that is what a real dietary harm looks like when you remove it. A policy change, a control group, and fewer people in hospital. It is the single clearest natural experiment in modern nutrition.

And it is the comparison the current claim has never produced.

Is soybean oil bad for you?

So the hydrogenation is gone. What is left in the bottle is the oil itself, and the accusation against it has moved to the linoleic acid.

We tested that claim on its own terms in are seed oils bad for you, and the short version is that the named mechanism fails at the first step: cut dietary linoleic acid by up to 90% and the arachidonic acid it is supposed to become does not move. Thirty randomised trials measuring inflammation directly found nothing.

That page is also honest about the other half — two recovered BMJ trials where swapping saturated fat for vegetable oil produced no mortality benefit, and one where the intervention group died more. Go and read it if you want the full argument; we are not going to relitigate it here.

What can be added specifically about soybean oil is where it sits against other fats. A network meta-analysis put 54 randomised trials together and ranked thirteen oils and solid fats on blood lipids [4]. Soybean oil sits in the unsaturated cluster with the rest — behind safflower and rapeseed on LDL, and comfortably ahead of butter, which every single oil tested beat.

What is the healthiest cooking oil?

This is the fourth page we have written about cooking oil, so we can finally answer that properly, and the answer is duller than the question deserves.

On blood lipids, safflower ranks first and rapeseed second across 54 trials [4]. On our other pages: canola beat olive oil on LDL by 6.13 mg/dL in thirteen head-to-head trials, and olive oil showed no advantage over other vegetable oils at all in the largest mortality analysis available.

Put those together and the honest conclusion is the one none of the marketing wants: among unsaturated cooking oils, the differences between them are small enough that the choice barely matters. What moves the numbers is replacing butter, and replacing the fats inside fried and packaged food.

After that, buy on taste, smoke point and price. Those are real differences. The health gap between one unsaturated bottle and the next is not.

What we are rating

Unsupported: that vegetable oil as sold today is harming you. The mechanism offered fails when tested, and the oil sits with the other unsaturated fats on every lipid comparison we have.

Supported, historically, and now fixed: that partially hydrogenated vegetable oil harmed people. It did, the effect was large enough to see in hospital admissions, and removing it worked [2].

Genuinely true and worth sitting with: the exposure change is real and enormous — a thousandfold rise in supply, and a 136% rise in what is stored in people [1][3]. Anyone who tells you nothing changed is not being straight with you either.

Untested: what that exposure does when it arrives, as it mostly does, inside fried and ultra-processed food.

What to actually do

Check for “partially hydrogenated” on any label and put it back. That is the ingredient with a body count and a natural experiment behind it. It is largely gone from the food supply, but the phrase is the one worth recognising.

Do not pay extra to avoid the anonymous bottle. On blood lipids, soybean oil sits with the other unsaturated oils and ahead of butter [4].

Judge the food, not the oil. Almost all the vegetable oil most people eat arrives inside fried and packaged food. Cut those and your linoleic acid falls as a side effect — along with a dozen other things that have better evidence against them.

And notice what happened here. A real harm was identified, regulated, and removed, and the fear outlived the thing that caused it and reattached itself to what was left. That is worth watching for, because it is not the only claim it has happened to.

This is journalism, not medical advice. Cholesterol and heart-disease decisions belong with a clinician who knows your numbers.