The core argument against seed oils is that their omega-6 content drives chronic inflammation throughout the body. Johns Hopkins nutrition scientist Matti Marklund directly addressed this claim, explaining that seed oils do not cause inflammation the way online critics suggest. His research group found that fatty acids typical of seed oils, particularly linoleic acid, are associated with lower risk of chronic diseases like cardiovascular disease, heart attack, stroke, and diabetes, not higher risk.

A separate review in the Journal of the American College of Nutrition looked specifically at whether omega-6 fatty acids independently raise inflammatory markers in healthy adults, and found only limited evidence that they do. Some laboratory and animal studies have suggested that excessive omega-6 intake could theoretically promote inflammatory pathways, but human trials have produced far more mixed, and generally reassuring, results.

Where the concern has real footing is in the modern omega-6 to omega-3 ratio. Western diets today run somewhere between 15:1 and 20:1, far higher than the roughly 1:1 ratio ancestral diets are estimated to have had. Researchers still debate exactly how much that shift matters on its own, but the fix isn’t cutting omega-6 to zero, since it’s an essential nutrient. It’s adding more omega-3 sources back in, things like fatty fish, walnuts, and flaxseed, rather than eliminating an entire category of fat.

A 2025 systematic review published in Frontiers in Nutrition pulled data from PubMed, Scopus, Web of Science, and the Cochrane Library, screening specifically for randomized, placebo-controlled, and double-blind clinical trials rather than weaker observational studies. Across 11 qualifying clinical studies, oils derived from canola, flaxseed, and sesame seeds were found to positively influence lipid profiles and glycemic control in patients who already had diabetes or dyslipidemia, two of the exact conditions critics claim seed oils make worse.

Separately, a widely cited 2020 meta-analysis published in Circulation found that replacing saturated fat with polyunsaturated fat, the dominant fat category in most seed oils, was associated with a 17% reduction in cardiovascular events. That’s one of the more consistent findings in nutrition science over the past decade, and it lines up with decades of dietary guidance from major health organizations.

What makes the 2026 Critical Reviews in Food Science and Nutrition paper notable is that it wasn’t a single new study, it was a synthesis of the entire body of existing clinical and observational research on linoleic acid and seed oils. When researchers pool decades of trial data like that and still land on “the totality of evidence supports safety and benefits,” that carries more weight than any single headline-grabbing study in either direction, including the ones that originally fueled the online panic.

Refined oils go through heat extraction, chemical treatment, and a deodorizing and bleaching process that uses activated carbon or Fuller’s earth rather than actual bleach. That processing raises the smoke point and extends shelf life considerably, but it also strips out some natural nutrients, aroma, and flavor compounds along the way. Unrefined, cold-pressed oils keep more of those nutrients and flavor since they’re extracted through pressure rather than heat, but they oxidize faster and can’t handle high heat without breaking down into less stable compounds.

Oxidative stability is where legitimate kitchen caution actually belongs, more so than the seed-versus-fruit origin of the oil itself. Reused frying oil accumulates polar compounds with each heating cycle, and industry testing has found that a soybean oil’s smoke point can drop by 20 to 30 degrees Fahrenheit after just four frying cycles. Oils also degrade faster when stored near heat, light, or left uncapped between uses.

In practice, this plays out differently across specific oils. Refined canola and refined vegetable oil sit in the roughly 400 to 450°F range and work well for weeknight sautéing. Light refined olive oil, despite still technically being an olive product rather than a seed oil, follows the same refined-oil pattern at around 465°F. Extra virgin olive oil, unrefined and full of flavor, sits much lower around 350°F, which is exactly why it belongs on a salad or drizzled over finished vegetables rather than in a screaming-hot pan.

Instead of avoiding an entire category of oils based on internet fear, the more evidence-based approach is choosing oils based on what you’re actually cooking that day. For high-heat searing, roasting, or deep frying, refined oils with higher smoke points, like refined canola, avocado, or light olive oil, hold up better without breaking down into potentially harmful compounds. For dressings, dips, or finishing drizzles, unrefined extra virgin olive oil or a cold-pressed oil brings more flavor and retains more of its natural micronutrients, since it never sees high heat in the first place.

A practical two-oil system covers almost every home cooking situation: one refined, high-smoke-point oil for the stovetop and oven, and one high-quality unrefined oil kept specifically for finishing and salads. From there, specialty oils like toasted sesame or walnut oil can be added for flavor rather than as a daily cooking staple.

What this looks like on an actual weeknight: searing chicken thighs or roasting a tray of vegetables calls for the refined bottle, since it can handle 400°F-plus oven and stovetop temperatures without smoking or breaking down. Tossing a quick salad or finishing a bowl of soup calls for the unrefined bottle, where the flavor actually gets to shine instead of burning off. Neither choice requires avoiding an entire aisle of the grocery store.

According to Marklund and other nutrition researchers, this category of oils has largely been demonized based on a misunderstanding of how they’re made and how the human body actually uses the fats inside them, combined with the fact that they show up constantly in ultra-processed foods. That correlation, showing up in the same foods linked to poor health outcomes, gets mistaken for causation. It’s the ultra-processed food itself, loaded with refined starch and added sugar, that’s more plausibly driving the outcomes people end up blaming on the cooking oil.

There’s also a social media dynamic at play. Claims that a common, cheap pantry staple is secretly dangerous spread faster than claims that reinforce the boring, decades-old consensus. That doesn’t make the fear-based content malicious, but it does mean the loudest voices on a topic aren’t necessarily the most accurate ones, and it’s worth checking what actual researchers publishing in peer-reviewed journals are finding before changing a habit based on a video clip.