Maybe you’ve seen some ominous videos on TikTok showing vegetable or canola oils against scary music. Or heard self-proclaimed fitness gurus denouncing a group of seed oils they call the “hateful eight” – canola, corn, cottonseed soy, sunflower, safflower, grapeseed and rice bran.
Some of the most common cooking oils – once lauded for being plant-derived and featuring unsaturated fats – are now coming under attacks worthy of a Hollywood action movie. Instagram and TikTok are full of videos decrying seed oils for leading to any number of health concerns such as inflammation and reduced testosterone in males.
A report from Harvard’s School of Public Health says those fears are overplayed, though.
So what does the science say about these common cooking oils, and how can consumers trudge through an oily mess of conflicting information?
Seed oil is a blanket term referring to a number of plant-derived oils created when their seeds are pressed. Usually heated and extracted through chemical means, seed oils are also called “refined” oils.
Inexpensive and generally flavor-neutral, seed oils are used in a dizzying variety of foods, from French fries and potato chips to bottled salad dressings and margarine.
The unsaturated fats found in seed oils are generally healthier than the saturated fats you’d find in meat and dairy products, says Hope Brinkmann, a registered dietitian at Tidelands Health.
The problem? The unsaturated fats in seed oils are generally dominated by omega-6 fatty acids, a reference to their chemical bonding structure. Doctors have been warning for at least a decade that Western diets are dangerously heavy in omega-6 fatty acids, setting the stage for hypertension and inflammation.
The concern drives some to choose cooking oils with a different chemical structure, called omega-3 fatty acids.
Popular omega-3 oils include fish oil, flaxseed oil, avocado oil and olive oil (especially “extra virgin” olive oil, a reference to olives that have been only minimally processed and therefore retain the most omega-3 fatty acids).
The advantage to omega-3 fatty acids is that they have a chemical structure that has been linked to a number of heart and other health benefits, Brinkmann says.
However, the benefits of omega-3 fatty acids don’t mean that seed oils containing omega-6 fatty acids are bad.
After all, processed foods made with seed oils are also commonly loaded with salt, sugar and carbohydrates. These ingredients, researchers say, are probably more concerning than omega-6 fatty acids.
Brinkmann tells her patients that there is no need to avoid seed oils, just to avoid eating too many processed foods. It’s part of her overall approach to seeking a healthy mix of foods, rather than demonizing anything as off limits.
“All foods can fit” in a healthy diet, Brinkmann says, “it’s just a matter of the function that they serve.”