If you follow any health influencers on social media, there’s a good chance you’ve encountered those who proclaim that certain oils are killing us and that we should avoid them at all costs. The oils they’re referring to usually include seed oils, like canola oil, corn oil, grapeseed oil, peanut oil, soybean oil and sunflower oil, among others.
These influencers are typically basing their declarations on a handful of studies—some poorly designed—and sometimes just parroting what other influencers are saying.
But is it true that we should throw out and avoid any foods with seed oils—including foods we make at home? Seeds themselves are a healthy choice for most. Why would their oils be toxic and cause inflammation like these influencers are suggesting?
Gastroenterologist Will Bulsiewicz, M.D., recently shared that he thinks much of the social media concern is overblown. What most folks are missing, Bulsiewicz said, is something to compare seed oil’s nutritional value to.
Nutrition doesn’t happen in a vacuum. When you ask yourself if something is healthy, you also need to ask, “Compared to what?” In the case of seed oils, the “compared to what” is usually saturated fat.
Bulsiewicz added that studies suggest that compared to saturated fat from foods like butter and coconut oil, oils rich in unsaturated fats were preferred for better LDL cholesterol levels, weight maintenance and reduced inflammation.
Unsaturated fats are typically oils, including seed oils, and can be polyunsaturated or monounsaturated. Polyunsaturated fats include omega-3 fatty acids and omega-6 fatty acids. Omega-3s come from things like fatty fish—salmon, tuna and sardines—as well as seeds and nuts, like walnuts and chia seeds. Omega-6s are found in foods like corn, soybeans, sunflower seeds and safflower oil.
It’s important to note that many sources of polyunsaturated fats have a mix of both omega-3 and omega-6 fatty acids. Walnuts are a prime example of this.
But omega-6 fatty acids have gotten a bad reputation over the years. So, what is the truth about omega-6s? Are they harmful?
A new narrative review published on October 30, 2024, in the British Journal of Nutrition attempts to clear up some of the confusion. Here’s what you need to know.
How Was This Study Conducted & What Did It Show?
This study is a narrative review, which means that researchers took studies that were previously done on the topic of seed oils and health and simply reported the findings. They didn’t analyze the information or critique it. While the study was financially supported by the United Soybean Board, National Corn Growers Association, Corn Refiners Association, Canola Council of Canada and U.S. Canola Association, its findings are backed up by other research, too.
The researchers found overwhelming evidence in favor of omega-6 polyunsaturated oils (n-6 PUFAs) over rich sources of saturated fats, like butter, tallow, lard, duck fat, ghee, palm oil and coconut oil. The main n-6 PUFA this review looked at was linoleic acid, found in high amounts in soy, corn and canola oils.
Linoleic acid (LA) and its omega-3 cousin, alpha-linolenic acid (ALA), are considered essential fatty acids because our bodies cannot make them on their own. This means we must get them from food sources.
“Strong and consistent evidence shows higher intake of n-6 PUFA, particularly linoleic acid, is associated with lower risk of heart disease,” says Kristina Petersen, Ph.D., an associate professor in nutritional sciences at Penn State and the study’s lead author. “Evidence from clinical trials shows intake of n-6 PUFA instead of saturated fat improves major risk factors for heart disease. Also, clinical trials show that increased n-6 PUFA—linoleic acid—intake does not increase markers of inflammation or oxidative stress.”
Inflammation and oxidative stress are points that some social media influencers really drive home. And they aren’t entirely wrong—in some contexts, n-6 PUFA intake can be cause for concern. For example, Bulsiewicz points out that many ultra-processed foods contain PUFAs—and overconsumption of them may cause inflammation and oxidative stress, in part, because they often replace whole foods and foods high in fiber. Ultra-processed foods include things like chicken nuggets, frozen pizza, hot dogs, cookies and cakes.
Another claim many researchers and social media influencers make is that Americans consume too many PUFAs. But Petersen challenges this belief based on the review, stating, “The current U.S. intake of oils is in the range recommended for heart health.”
Petersen also challenges the “ideal” ratio of omega-6s to omega-3s that is often touted by health professionals and other researchers—between 2-to-1 and 4-to-1 omega-6 to omega-3 intake. In other words, for every 2 to 4 grams of omega-6s, experts say you should balance that with 1 gram of omega-3s.
Petersen states, however, that the evidence shows the ratio is less important than simply getting a mix of the two—and reducing saturated fat intake. “The ratio of PUFA to MUFA is not important,” says Petersen. “The important thing is to consume MUFA and PUFA instead of saturated fats.”
Essentially, it comes down to what we at EatingWell promote—eating a wide variety of foods, including whole grains, lean proteins and sources of healthy fats, like nuts, seeds, oils and fatty fish—so that you get the nutrients you need. If you need some guidance, following the Mediterranean diet will help.
How Does This Apply to Real Life?
Petersen sums up the narrative review by stating, “There is a lot of misinformation about oils on the internet. Collectively, the available evidence does not support claims of harm, and in fact, shows oils, particularly n-6-containing oils, improve heart health.”
And since heart disease is the leading cause of death in the U.S. and globally, it’s important to do what we can to prevent it. So while it’s OK to enjoy your favorite fast-food burger and fries or frozen pizza now and then, you don’t want to make ultra-processed foods your primary source of omega-6s—or any other nutrients for that matter. Instead, use these oils in things like salad dressings or dips and for sautéing foods. Oils like canola and peanut oil have higher smoke points than olive oil, making them a better choice for higher-heat cooking.
And don’t worry as much about your ratio of omega-6s to omega-3s. Really, how cumbersome would it be to have to measure all your food and figure out the amount of fatty acids in it? Instead, include a variety of foods so that you also get a wide range of fatty acids.
As far as saturated fats go, there are different types of those, too—and there is some evidence suggesting that the saturated fat found naturally in whole foods like milk and eggs is not as harmful as once thought. Again, it’s the added saturated fat found in ultra-processed foods that is the biggest problem regarding heart health.
The Bottom Line
Seed oils can definitely be part of a healthy eating pattern, as this study suggests. When you trade saturated fats for unsaturated fats like seed oils, you’re often making a heart-healthy choice that your ticker will thank you for. Plus, folks who consume more linoleic acid, of which soy, corn and canola oils are a good source, did not experience elevated levels of inflammation or oxidative stress.
So go ahead! Use canola oil in your quick bowl of ramen and Carrot Cake-Inspired Loaf Bread. Or peanut oil in Thai Curry-Chile Dip or Shrimp Pad Thai. And remember that you can’t always believe what people are saying on social media—especially if they suggest cutting out a food entirely.
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