Seed oils are a hot-button topic in the nutrition world, sparking heated debates on social media and beyond. In one camp, experts say they’re completely harmless, that the whole conversation is overblown. On the other side, though, seed oils are being referred to as “poison” and “toxic,” with a call to ban them entirely.
Just last month as this column was going to print, Louisiana lawmakers passed a bill to discourage restaurants and food manufacturers from using seed oils. And if they continue to use them, they’ll have to flag it on the menu or label so that it’s visible to consumers (this is slated to go into effect in 2028, to give the industry time to change course).
So what’s the real story on seed oils? As is often the case, the truth lands somewhere in the middle.
What Are Seed Oils?
They’re referred to as seed oils because they’re extracted from the seeds (rather than the fruit) of plants like soybeans, corn, safflower, sunflower, canola, cottonseed and grapeseed. They’re cheap, shelf-stable and often subsidized, making them a go-to option for restaurants and food manufacturers.
To dive deeper into the research, I’ve reached out to experts in the field, including Dr. Mary Sco, MD, PhD, a family medicine doctor who also has her doctorate in Nutritional Sciences. You can hear our interview in full in my podcast, FUELED Wellness + Nutrition; below is a summary of our conversation.
The Omega-6 Factor
Much of the debate around seed oils centers on their omega-6 concentration. In simple terms, omega-6 fats can be pro-inflammatory, while omega-3 fats (like those found in oily fish and plant-based foods like walnuts and flax) have an anti-inflammatory effect.
This doesn’t mean that omega-6s are always harmful – but they can tilt the inflammatory balance if consumed in large amounts without enough omega-3s to compensate. And chronic inflammation can contribute to conditions ranging from heart disease to cancer and more.
“Until about a hundred years ago, the ratio of omega-6 to omega-3 fats in our diets was about 4:1, if not less. Now, that ratio is at least 20:1,” notes Dr. Sco. “And over the last 50 years, the concentration of omega-6 fatty acids in Americans’ fat tissue has more than doubled. We’re now surrounded – literally – by more omega-6 fatty acids than at any other time in history.”
“It’s important to note that, within the category of ‘seed oils’ there is still a lot of variation,” says Dr. Sco. “Canola oil, for example, has a better ratio of omega-6 to omega-3 fatty acids (2:1) than soybean oil (8:1) and a far more favorable balance than corn oil (46:1) or sunflower oil (128:1).”
Heart Disease Controversy
There’s also heated debate around seed oils and heart health. By replacing saturated fats like butter or beef tallow with plant-based fats, including seed oils, studies have shown modest reductions in LDL cholesterol. Yet some older research, such as the Minnesota Coronary Experiment, found that replacing animal fats with seed oils did not necessarily reduce death rates from heart disease – and, in some cases, mortality risk went up.
The Heated Question
Another point of concern is how seed oils behave at high heat. Prolonged or repeated heating of seed oils – like what happens with restaurant deep-frying or ultra-processed foods – can produce harmful byproducts including lipid oxidation, linked to conditions like elevated blood pressure and vascular inflammation that raise our risk for cardiovascular disease, among other negative effects.
Risking a Health Halo
When we single out an ingredient, there’s a risk of creating a ‘health halo’ that otherwise unhealthy foods do not deserve.
Take Doritos, for example. If the brand were to replace the seed oils (listed as ‘corn, canola, soybean and/or sunflower oil’) with other fats like beef tallow or avocado oils, they’re still just a low-quality, ultra-processed snack filled with refined carbs, MSG and artificial food dyes, among other not-so-natural ingredients.
Similarly, if a fast food chain touts that they don’t use seed oil for their flour-battered chicken on processed white bread with french fries, it’s still just a fried chicken sandwich with fries.
Finding Your Balance
“Some people – especially those with inflammatory conditions or those prone to migraines – might benefit from reducing their intake of seed oils,” says Dr. Sco. “But it’s never the whole answer.”
“Sugar, refined carbs, alcohol and overall excess calories can also drive inflammation,” says Dr. Sco. “Fixating on seed oils alone can mean that we miss the other culprits.”
“Eat fewer fried foods, cut back on ultra-processed snacks, and emphasize whole foods whenever you can, also balancing your fats by including sources of omega-3s like salmon, sardines, flaxseed, and walnuts,” advises Dr. Sco. “By doing that, you’ll naturally dial down your omega-6 intake and you’ll do your body far more good than any single ingredient swap ever could.”
