Are seed oils actually bad for your health? Here's the science behind the controversy

Seed oils, commonly called rootlike oils, are extracted from nan seeds of plants. alaskla/iStockphoto/Getty Images hide caption

toggle caption

alaskla/iStockphoto/Getty Images

By now, you mightiness person heard that seed oils are bad for you — if not from societal media wellness influencers, past from Health Secretary Robert F. Kennedy Jr. himself.

Kennedy has said these rootlike oils — extracted from nan seeds of plants, for illustration canola, soybean and safflower — are poisoning Americans and driving nan obesity epidemic. Part of nan grounds he points to is that obesity rates started to emergence arsenic seed oils began to predominate nan American diet.

Many nutrition and wellness researchers opportunity that while seed oils mightiness not beryllium arsenic bully for you arsenic oliva oil, claims that they're harmful to wellness person been stretched excessively far.

"This is 1 of nan much studied topics successful nutrition. So it's benignant of other bewildering to rather a fewer of america successful nan section that this is coming up," says Christopher Gardner, a nutrition intelligence and professor of medicine astatine Stanford University.

He says studies person consistently shown that replacing saturated fats, specified arsenic lard aliases beef tallow, pinch fats from works oils leads to amended wellness outcomes.

Still, Kennedy celebrated when nan fast-food concatenation Steak 'n Shake announced earlier this twelvemonth that it would extremity making its gallic fries pinch seed oils and usage tallow — rendered beef fat — instead.

When we reached retired to Secretary Kennedy, his squad pointed america to the MAHA report, which says that seed oils lend to imbalances of fatty acids that play "a imaginable domiciled successful inflammation."

So what is nan subject connected seed oils? Let's unpack immoderate of nan criticisms.

Refining pinch chemicals and heat

Seed oils — commonly called rootlike oils — are extracted from nan seeds of plants.

Critics thin to attraction connected 8 circumstantial oils, sometimes referred to arsenic nan "hateful eight": soybean, canola, corn, cottonseed, sunflower, safflower, atom bran and grapeseed.

To maximize really overmuch lipid is drawn retired of these seeds, manufacturers usually process them utilizing power and chemicals, explains Eric Decker, a professor emeritus of nutrient subject and lipids interrogator astatine nan University of Massachusetts Amherst. It's a cheaper and much businesslike process than mechanically pressing nan lipid out. By comparison, other virgin oliva lipid is squeezed retired of nan consequence without nan thief of chemicals aliases heat.

Decker says critics often raise concerns astir nan astir commonly utilized solvent successful refining seed oils — hexane — which is hazardous. The hexane is removed during processing, "but you extremity up pinch very mini amounts near successful nan oil," he says.

However, Decker says these residues are astatine levels excessively debased to beryllium toxic. A toxicology study from nan national government, published successful April 2025, called nan magnitude "toxicologically insignificant." And immoderate residual hexane is apt to evaporate erstwhile you power your lipid during cooking, Decker says.

Caitlin Dow, a elder nutrition intelligence with nan Center for Science successful nan Public Interest, says she's personally not concerned astir hexane residues successful seed oils, but if you are, you tin ever bargain integrated seed oils — they aren't processed pinch hexane, but they do costs more.

Do seed oils beforehand inflammation?

One communal statement against seed oils is that they beforehand inflammation — a physiological consequence that helps nan assemblage heal from infection aliases injuries. President Trump's nominee for surgeon general, Dr. Casey Means, has written that seed lipid "increases inflammation successful nan body." Too overmuch inflammation complete a agelong play of clip — chronic inflammation — tin lead to wellness problems for illustration autoimmune diseases, bosom illness and definite cancers.

This thought is rooted successful nan kinds of fats recovered successful these oils, says Sarah Berry, a professor of nutrition astatine King's College London.

Seed oils thin to person higher levels of basal fatty acids called omega-6s and little levels of different basal fatty acids called omega-3s. These fatty acids play a domiciled successful tons of different assemblage processes, including regulating inflammation. Berry says our bodies thin to person omega-3s into chemicals that conflict inflammation," while omega-6s tin beryllium converted into chemicals that beforehand inflammation.

That's why critics opportunity you shouldn't eat seed oils that are precocious successful omega-6s, because they reason that this will beforehand chronic inflammation.

Berry says that mightiness make consciousness successful theory, "but it doesn't play retired successful existent life, it doesn't play retired successful nan quality body."

Berry says randomized controlled tests person recovered that, erstwhile group devour much seed oils, they don't show signs of excess pro-inflammatory compounds successful their tissues, and they don't person much markers of inflammation.

There's besides beardown grounds that omega-6s thief little levels of bad cholesterol, which reduces nan consequence of bosom disease, which is why nan American Heart Association supports eating them arsenic portion of a patient diet.

One interrogator who has spent decades studying fatty acids is Tom Brenna of nan University of Texas astatine Austin. He is concerned that immoderate group whitethorn beryllium eating excessively galore omega-6s successful their fare from seed oils, because not everyone processes omega-6s successful nan aforesaid way. He says emerging investigation suggests immoderate group whitethorn beryllium much susceptible to inflammation from omega-6s.

The omega-6 & omega-3 balance

Most Americans eat astir 10 times much omega-6 fats than omega-3 fats. And each nan nutrition researchers we said pinch work together that for amended health, it's a bully thought to bring that intake into amended balance, though nan nonstop ratio has not been defined, according to nan National Institutes of Health.

Since astir group get plentifulness of omega-6s successful their diet, nan wide proposal is to up your intake of omega-3s. Fatty food for illustration salmon, mackerel and sardines, and plants including walnuts, flaxseeds and chia seeds are each rich | sources of omega-3s.

And Brenna says you shouldn't extremity eating omega-6s altogether.

"Some of nan influencers are talking astir getting free of each nan omega-6 successful nan diet," Brenna says. "And that would beryllium a unspeakable idea," he says. "Some omega-6 is perfectly required. The mobility is really much?"

Brenna says he sticks mostly to oliva lipid — which is simply a consequence lipid — though he notes that if everyone only utilized oliva oil, "there isn't capable oliva lipid successful nan world" to meet demand. And he says it's expensive.

Another option: usage seed oils branded arsenic "high oleic." These oils person little levels of omega-6s and fatty acerb profiles akin to oliva oil.

Nutrition intelligence Caitlin Dow is not worried astir seed oils. She has a vessel of canola lipid successful her pantry. On a caller afternoon, she was utilizing it to stir-fry vegetables — doorbell peppers, zucchini, carrots and broccoli.

"I don't want group acrophobic to usage seed oils reasoning that they're doing thing bad for their wellness aliases their family's health," she says. "They're not doing thing bad. It's a overmuch healthier action than switching to lard aliases food aliases coconut oil."

One point to support successful mind erstwhile utilizing rootlike oils is that you should debar many times reheating nan aforesaid lipid astatine precocious temperatures, for illustration you mightiness do pinch a heavy fryer — which are communal successful restaurants and fast-food chains. Over time, that tin lead to changes successful nan oil that can beforehand inflammation successful nan body.

But nan take-home connection here, Decker says, is to eat little fried food. "In general, fried foods don't really correspond a patient class that we should beryllium eating connected a regular basis."

And that brings america to ultra-processed foods

The main logic why our seed lipid depletion has accrued dramatically is because these oils are ubiquitous successful ultra-processed foods, which now predominate nan U.S. nutrient supply.

And 1 point everyone seems to work together connected is that Americans should eat less ultra-processed foods, which thin to beryllium precocious successful sugar, brackish and unhealthy fats, arsenic good arsenic preservatives, artificial dyes and different additives. There is lots of grounds that shows eating excessively overmuch ultra-processed food is linked to mediocre wellness outcomes.

"So galore of nan seed lipid haters show these beautiful graphs showing how, arsenic intakes of seed oils person accrued complete nan years, truthful person rates of each of these atrocious chronic diseases – cancer, cardiovascular disease, Type 2 diabetes, obesity," Berry says. "But look what other has changed. Our nutrient scenery is almost unrecognizable now compared to really it was 50 years ago."

Berry and Gardner opportunity you can't azygous retired seed oils for this relationship erstwhile ultra-processed foods are often precocious successful different ingredients known to thrust mediocre health.

"Is it nan junk nutrient that's causing these wellness issues aliases is it nan seed oils? And I person ever thought it's nan junk foods," Gardner says.

Instead of focusing connected which oils you eat, Gardner says attraction connected your wide diet. Gardner, Berry and Brenna each work together that intends cutting backmost connected ultra-processed foods and cooking astatine location more. And make judge to get plentifulness of fruits, vegetables, legumes, nuts and seeds and omega-3s from foods for illustration fish.

And if you usage immoderate seed lipid to make a crockery dressing that encourages you to eat much vegetables, Gardner says — that's a triumph for health.

NPR requested an question and reply pinch Secretary Kennedy for this communicative but did not perceive back.

Edited by Jane Greenhalgh