Why TikTok Hates Seed Oils, and Should You?

Sam Westreich, PhD

A new dietary trend on the internet — is it fact or bullshit?

Could this oil be responsible for murdering your entire family? Better read on to find out.Photo by Roberta Sorge on Unsplash

There are a lot of strange and dubious claims on the internet when it comes to diet and health. They’re circulated by a strange web of conspiracy theorists, influencers, exercise gurus, and others. They range from claiming the awe-inspiring benefits of Manuka honey to decrying the value of eggs to claiming that all plants are toxic, so we should only eat the creatures that eat those plants (ignore how those creatures suffer no ill effects)!

But a new one came across my desk recently: seed oils.

Seed oils, according to a wide and curiously disparate range of resources, are bad for us. Really bad. Claimants link them to:

  • Obesity (when a third of Americans are obese, this seems like an obvious condition to link to… anything in the American diet?)
  • Diabetes (also commonly mentioned by most pseudoscience)
  • Autoimmune diseases
  • Neurodegenerative diseases, including Alzheimer’s
  • Gut microbiome issues (instant bullshit alert, buzz buzz)
  • “Inflammation” and “toxicity” (which should also set off your bullshit detectors)
  • Sunburn?

Is there truth to these claims? Or is it all nothing but hot air… er, hot oil? Let’s see if there’s science behind the TikTok claims.

What are seed oils, anyway?

If you visit a grocery store, you can likely find several different types of cooking oil. We’ve got olive oil, peanut oil, corn oil, canola oil, the very-generally-labeled “vegetable oil”, and some other specialty oils that might command a higher price point, like coconut oil or avocado oil.

All of these oils come from plants, and most from the fruit/seed of the plant. But most anti-seed oil advocates speak out against canola, soybean, sunflower, safflower, corn, and grapeseed oils.

Pretty much all oil is made of fat. The difference focuses on what type of fat is in it.

On nutrition labels, we’ve probably seen “total fat” split out into categories like saturated, monounsaturated, and poly-unsaturated fats. Let’s briefly talk chemistry.

All oils are made of a long chain of carbon atoms, with a hydroxyl group (COOH) at one end. Don’t worry about that hydroxyl thing, just focus on the long chain of carbon.

Each carbon atom can bond to 4 things. Two of those bonds are the links connecting it to the chain. The other two bonds can either connect it to the neighbor carbon atoms, or can be attached to hydrogen atoms.

A diagram of a molecule with one double bond between carbons, making this monounsaturated.Source: Socratic.org

If there are no double bonds and all the carbons have 2+ hydrogens, the fat is called “saturated”.

If there is a single double bond, like in the picture above, it is monounsaturated (mono meaning one).

If there are 2 or more double bonds, it is polyunsaturated fat.

Why do we care? Some types of fats appear to be be healthier for us than others. In general, unsaturated fats (that is, those with one or more double bonds, like in the picture above) seem to be correlated with a lower risk of heart disease. Saturated fats, on the other hand, are linked with higher levels of low-density lipoprotein (LDL, the “bad” cholesterol) in the bloodstream and worse heart health. Finally, some polyunsaturated fats, commonly known as omega-3 fatty acids, are linked with better heart health and lower blood cholesterol levels.

Okay. Which oils contain which fat types?

  • Saturated fat: animal fats like beef tallow, dairy, and coconut oil.
  • Monounsaturated fat: olive, canola, peanut, sunflower, and safflower oils.
  • Polyunsaturated fat: sunflower, corn, soybean, and cottonseed oils. Also in other foods, like walnuts, pine nuts, pumpkin seeds, and fatty fish (like salmon).

Let’s summarize:

When we talk about “seed oils”, we’re really talking about unsaturated fats.

The arguments against seed oils

The anti-seed oil arguments blew up recently thanks to famed pseudoscience embracer Joe Rogan, who interviewed a keto guru, Paul Saladino (who advocated for an all-meat diet, which is a terrible idea) and Cate Shanahan, who blames seed oils for all the evil occurrences listed at the start of this article.

They argue that:

  • Seed oils are extracted through industrialized processes (true), which involve chemical solvents (true) and are less healthy because they are less natural (questionable).
  • There’s a powerful seed oil lobby that pushes for these to be classified as healthy, similar to how dietary guidelines vilified fats in the 80s and 90s, instead of targeting sugar (no evidence provided of this lobby).
  • Seed oils are cheap, so they are often used as ingredients in low-quality, highly processed foods. They also are often chosen for unhealthy foods because they are fairly shelf-stable (true).
  • Seed oils break down into toxins when you cook them (only if burnt, see below).
  • Seed oils go into your skin and cause inflammation, which can, among other things, make you more vulnerable to sunburn (false).
  • The mainstream research is funded by corporate interests and is all wrong, and saturated fats are actually healthier than unsaturated ones, the government and scientists are lying to you because they’re all in the pocket of Big Cooking Oil (conspiracy nonsense).

Some of these are reasonable, some are… decidedly less so.

What the actual science says

Seed oils in processed foods: generally bad. Overall, most processed foods are going to be high in carbs and sugar, low in vitamins, fiber, and other beneficial nutrients (vitamins are expensive, yo!). But many seed oils are hydrogenated, a process that makes them more shelf-stable but less healthy.

Some seed oils may cause inflammation, but some reduce it — and they’re still better than animal fat. Specifically, polyunsaturated fats are either type omega-3 or omega-6. Omega-6 polyunsaturated fats have been linked to inflammation, but omega-3s reduce it. And saturated fats (animal fats) are the strongest causers of inflammation.

Seed oils in cooking are fine, as long as you don’t heat them beyond their smoke point. There’s a lot of talk of seed oils “breaking down into toxins”, but this only happens if you overheat them past their smoke point, which is when they oxidize and break down. This is also pretty obvious, as they’ll smell burnt.

In general, avoiding foods cooked in lots of seed oils is probably good — but because you’re eliminating fried unhealthy foods from your diet, not because of the oil.

The scientific research in seed oils is probably more trustworthy than influencers. Influencers like Cate Shanahan don’t often cite peer-reviewed studies, and her website also claims that seed oils are the reason why people are dying of COVID. Remember, if someone is making a health claim, the onus is on them to provide evidence to support their statement.

Seed oils won’t cure diseases, but they’re not likely to be causing them, either. Despite how we’d love to identify the one food that cures everything or causes everything, it simply doesn’t exist. Choosing more unsaturated fats, specifically leaning towards an even mix of omega-3 and omega-6 fats, while avoiding saturated fats, is good for us. But it’s not going to magically fix everything.

Our bodies are complex, and while our diet has a big impact on health, it’s not governed by a single food that we take in. Unless you are getting all your calories from drinking vegetable oil (if you are, stop that!), this is just one small contributing factor to your health.

Bottom line: seed oils aren’t your biggest villain

Seed oils are decent. All other things equal, they’re probably better for you than animal fat. Too much of them can be a problem, as can eating only one type of seed oil.

Seed oils can be a useful reason to avoid overly processed shelf-stable foods or fried foods, but they’re not the main reason why these foods are unhealthy. There’s nothing wrong with cooking at home with seed oils, as long as you don’t heat the oil to the point that it stinks and burns.

If you’re really worried about the oil levels in your diet, you can always try to aim for a more even balance of omega-3 vs. omega-6 unsaturated fats. Think eggs, soybeans, tofu, fish, seeds, and nuts.

And remember, if an influencer makes a health claim without providing a peer-reviewed citation to back it up, it’s probably bullshit!


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A microbiome scientist working at a tech startup in Silicon Valley, Sam Westreich provides insights into science and technology, exploring the strangest areas of biology, science, and biotechnology.

Mountain View, CA

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