What's the Deal with Seed Oils?
Seed oils, snake oil, and why we can’t resist a dietary villain
It’s the new year, and many of us are feeling that surge of optimism that comes along with rolling out freshly starched resolutions. We’re doing Dry January, re-upping our gym memberships, journaling, recommitting to meditation. Most of all, we’re atoning for all the fun things we’ve eaten lately, restoring our diets to a state of purity and discipline. We are activating broth mode.
It’s in this spirit of fresh starts and renewal that I write to you to clear up a few things about seed oils.
If you frequent a certain corner of the internet, you may have heard whispers that seed oils – canola, sunflower, soy, cottonseed, grapeseed, rice bran, corn, safflower – are America’s newest dietary villain. The claims are, basically, that seed oils are “toxic” due to their industrial refinement and fatty acid profile: not enough beautiful omega-3s, too many ugly omega-6s. Much is also made of the fact that the rising consumption of seed oils coincides with increasing levels of obesity, Alzheimer's disease, and diabetes. We’ve been warned to act fast. Swap out that bottle of Wesson for olive oil, avocado oil, coconut oil, beef tallow, or clarified butter.
These claims have been circulating for years, but lately the clamor against seed oils has gotten louder. Among their high-profile detractors today are RFK Jr., who has said that seed oils are poisoning us; Joe Rogan, who mistakenly believes that until recently humans didn’t eat oils from plants (in fact, we’ve been pressing seeds for oil since at least 400 AD); the Liver King, a fitness influencer whose He-Man physique was recently revealed to come from devouring steroids, not organ meats; and an anonymous figure named the Seed Oil Scout who apparently became radicalized after personally experiencing the gut-health benefits of a seed-oil-free life. He or she went on to design an app which allows users to see which restaurants use seed oils and which do not. It now has more than 600,000 downloads.
What the experts say
As TikTok influencers and the Make America Healthy Again crowd dig in, the nutrition and public health establishment have tried to push back with actual science:
Researchers at Harvard’s T.H. Chan School of Public Health have published several defenses of seed oils, pointing to the wealth of scientific evidence that seed oils – also called plant oils – are heart healthy. (To alarms about the trace levels of hexane found in some refined seed oils, they note that seed oils make up less than 2 percent of our day-to-day hexane exposure; the majority come from gasoline fumes.)
Dariush Mozaffarian, the vaunted dean of Tufts University’s Friedman School of Nutrition Science and Policy, defended seed oils too, explaining why unsaturated fats, like the ones in seed oils, are almost always preferable to saturated fats the internet mob recommends.
William Harris, an internationally recognized expert on omega-3 fatty acids who currently runs a company that sells omega-3 testing, has written extensively in defense of omega-6s, arguing that they have been incorrectly cast in a negative light.
Sarah Berry, a professor in the Department of Nutritional Sciences at King’s College London and one of the leading global experts on cardio-metabolic health, attempted to set the record straight in a podcast, during which she said, “it drives me insane that there is so much misinformation about the health effects of seed oils.”
And, if you need more proof, Consumer Reports and the New York Times [unlocked] have done an excellent job of debunking the prevailing online criticisms of seed oils. It’s a nuanced and detail-rich subject, and both pieces are worth a read if you want to go deeper on the topic.
If not seed oils…what?
For me, this is enough evidence to feel good about using canola oil to bake a cake or sauté some vegetables. But even if you find the judgment of journalists and tenured academics generally more compelling than that of the armchair biochemists who haunt Reddit, I can imagine there are still some people who might prefer a “better safe than sorry” approach. If seed oils are even possibly, maybe, a little bit suspect, why not just avoid them?
I posed this question to Christopher Gardner, a professor of medicine at Stanford University. Dr. Gardner has been conducting nutrition research at Stanford for over 20 years, and is a leading researcher in his field.
“A huge thing for me is ‘instead of what?’,” Gardner said. Which is to say: if you remove canola and sunflower oils from your diet, what will you be eating instead?
Seed oils proliferate in fast food and ultra-processed foods. If you eat less of those things to avoid seed oils? Great. You’ll probably be eating less fat, salt, sugar, refined grains, and calories overall. A positive dietary shift.
Gardner says that when it comes to your own kitchen, for cold or low-heat uses, high-quality, fresh olive oil is the clear upgrade from seed oil, if you can afford it.1 But avocado oil, which many seed oil detractors recommend, is “nutritionally very similar to canola or sunflower, and a lot more expensive.” Health-wise, it’s basically an even trade.
Then there are seed oil swaps that could turn out to be worse for your health; things get dicier when it comes to coconut oil, beef tallow, and grass-fed butter. These fats are having a moment in wellness circles because they contain some vitamins and certain (supposedly superior) fatty acids. But Gardner says that because they are so high in saturated fats, if you have elevated LDL cholesterol or any concerns about heart disease, there is strong scientific evidence that the risks of consuming them outweigh the benefits.
In short: Unless you’re deep frying, and using large quantities of oil, your choice of cooking fat is not something to get your knickers in a twist about. Exactly what you use for salad dressings or to pan-roast a piece of salmon won’t make a great deal of difference one way or another in the scheme of things. “If you cook with a little bit of butter versus a little bit of olive oil, a little bit of tallow, a little bit of canola oil, you wouldn’t see an impact on health,” Gardner said.
I recognize that this is boring advice, and that dull, sensible guidelines like these really lack that viral je ne sais quoi. This is why the internet is not permanently abuzz about wonders of the Mediterranean diet, even though the best research we have consistently confirms that it’s the healthiest way to eat.
It’s so much more fun to construct dramas in which certain foods are villains and others heroes; where beef tallow is a superfood and canola oil is toxic, rather than being a bit better or worse than the other. We love a story of good versus evil, and over the centuries, we’ve thrown so many different foods under the bus: raw fruits and vegetables, tomatoes, fat, sugar, carbohydrates, salt, gluten, dairy. Seed oils are just today’s roadkill.
If you’re also confused about olive oil, no worries. We have an olive oil buying guide coming soon!
I’ve not used seed oils in 50 years and in my mid 60’s I have zero plaque when tested by a CT scan. They are big Ag poison. Our ancestors never used them. My ancestors used olive oil and very occasionally animal fats. Telling anyone they can use seed oil sparingly is like telling a junkie Oxxy is ok.
American food is heavily adulterated. Cook fresh healthy food at home. Never eat fast food. Pizza once every few months might be ok as a treat. It’s been around for at least 2k years.
This article is terrible advise
Thanks for sharing your research on this. I’m constantly worried about GMO crops used to make these basic oils. Would you be able to share research on the effects of GMOs in oils and processed foods? I feel like there’s research to support or argue against everything, but I’d like to know what you’ve found!