If you’ve spent any time on health and fitness TikTok or Instagram, you’ve probably heard people warn you to throw out your seed oils immediately—or there will be serious consequences. Influencers claim they’re toxic, inflammatory, and even responsible for America’s obesity crisis. But is there any science behind these fears?
We asked a nutritionist to fact-check some of the most popular claims about seed oils and help you make an informed choice.
Myth 1: Seed oils are “toxic” and inflammatory
You may have heard that seed oils—like sunflower, soybean, safflower, or corn oil—are harmful because they’re full of “toxins” that cause inflammation. But according to MyFitnessPal nutritionist Brooke White, that belief doesn’t hold true.
“Seed oils get a bad rap,” she says. “They’re high in omega-6 polyunsaturated fats, which are actually essential—we need them for brain development, metabolism, and overall growth.”
While it’s true that omega-6 fats can contribute to the production of arachidonic acid, which is associated with inflammation, your body only converts a small portion of it. In fact, research shows that a diet rich in omega-6 fatty acids can help lower cholesterol and improve heart health.
Even more likely to trigger inflammation are ultra-processed foods that contain seed oils, as well as added sugars, sodium, and saturated fats. “There is strong evidence that reducing your intake of ultra-processed foods can support better health,” White says. “But that doesn’t mean seed oils used in home cooking or in whole foods are the problem.”
Myth 2: Seed oils were invented as industrial products
Yes, this group of oils has industrial uses. But that doesn’t mean they shouldn’t be in your kitchen.
Seed oils were originally extracted through mechanical screw pressing, an innovation in the 1880s that made oil production more efficient, White explains.
Today, these oils are used not only in food but also in environmentally friendly products like soaps and cosmetics. That’s not a red flag — in fact, it’s good for sustainability.
As for chemical processing? There are concerns about solvents like hexane used in the refining process. But White emphasizes that any residual amounts in the final oils are small and regulated.
The bigger problem is that when seed oils are overheated and used repeatedly (like in a restaurant fryer), this can lead to oxidation and the formation of harmful compounds.
Myth 3: Seed oils are to blame for rising obesity rates
This one sounds simple, but the truth is much more complicated.
“While seed oils are often blamed for rising obesity rates, other factors may play a bigger role,” says Lauren Kuda, a dietitian at MyFitnessPal. “Diets high in ultra-processed foods — many of which contain seed oils — are associated with poor health outcomes, but not just because of the oils. These foods are also high in calories, added sugars, and low in fiber and nutrients.”
In other words, the problem isn’t the canola oil in your homemade vinaigrette salad. The real problem is the combination of low-nutrient, high-calorie packaged foods that can lead to weight gain.
When people cut back on seed oils, it’s often part of a broader dietary change that includes eating fewer processed foods. That’s why people sometimes achieve weight loss by eliminating seed oils. It’s not just cutting back on the oils that does the trick.
Myth 4: Seed oils are high in “oxidized” fats that damage your cells
Seed oils contain polyunsaturated fats (PUFAs), which are sensitive to heat, light, and air. But that doesn’t mean they’re damaging your cells.
“The idea that seed oils are bad because they oxidize is misleading,” says MyFitnessPal dietitian Kathryn Basbaum. “They also contain antioxidants like vitamin E, which help prevent oxidative stress in the body. In fact, consuming these oils in moderation may help protect your cells.”
Basbaum recommends storing oils in a cool, dark place. And when cooking, don’t heat them to their smoking point. But when used correctly, these oils don’t carry the oxidation risks that some online voices suggest.
Myth 5: Fats like butter, ghee, tallow, or coconut oil are always healthier
This claim is often accompanied by the idea that “natural” fats are better than “processed” fats. But when it comes to heart health, saturated fat content matters more than social media trends.
“Fats like butter, ghee, tallow, and coconut oil are all high in saturated fat,” Basbaum says. “And too much saturated fat has been shown to increase heart disease risk and higher mortality.”
On the other hand, unsaturated fats found in olive oil, avocado, and canola oils have been shown to reduce heart disease risk.
This doesn’t mean you can never cook with butter or enjoy coconut oil in a recipe. But making unsaturated fats your default choice for everyday cooking can help support long-term health.
These oils may be scapegoats on social media, but the science tells a different story. They’re a source of essential fats your body needs and aren’t inherently harmful. The real health risks come from ultra-processed foods—not the oils themselves.
While it’s wise to be mindful of how you store and cook with oils, there’s no need to be afraid of using seed oils in salad dressings or stir-fries. Rather than being fooled by viral nutrition myths, focus on your overall eating patterns: more whole foods, less ultra-processed foods, and a balanced intake of healthy fats.
