Seed oils are the latest food villain to emerge on social media. You might have read about the dangers of the so-called “hateful eight,” a group of oils made from seeds like canola. Is it time to cancel these common cooking oils?
Take a deep breath. Seed oils are nothing to fear. “Despite what you may have heard, seed oils aren’t harmful,” says Brianna Scopel, RD, a registered dietitian at Henry Ford Health. “In fact, these oils are part of a healthy diet.”
Here’s what seed oils are, and what to know about them.
What Are the Hateful Eight Seed Oils?
Internet rumors have sprung up around a group of seed oils known as the hateful eight. These oils, extracted from the seeds of plants, include:
- Canola
- Corn
- Cottonseed
- Grapeseed
- Rice bran
- Safflower
- Soy
- Sunflower
Seed oils contain high levels of omega-6 fatty acids, a type of unsaturated fat. Critics claim omega-6s can lead to chronic inflammation and illness. But research doesn’t bear that out.
“Unsaturated fatty acids, including those from seed oils, can help to lower total cholesterol and reduce the risk of diseases like heart disease,” Scopel says.
Omega-3 vs. Omega-6 Fatty Acids
So how did omega-6s become the bad guys? To understand, it helps to know a bit about different types of fats.
Polyunsaturated fats, which come from both plant and animal sources, are considered healthy fats—especially if you eat them instead of saturated fats. (Saturated fats, which come from animal sources like butter or lard, increase cholesterol and heart disease risk.)
“Polyunsaturated fatty acids are essential nutrients,” Scopel explains. “The body can’t make them, so we need to include them in our diet.”
But there are two types of polyunsaturated fats. One type, known as omega-3s, is found in foods like salmon, walnuts and olive oil. Seed oils are rich in omega-6s, the other type.
In the U.S., people usually eat more omega-6s. But it turns out that omega-3s are a bit better for protecting the heart. That doesn’t mean omega-6s and seed oils are bad for you, however. “Variety is key to healthy nutrition, and we need both omega-3s and omega-6s,” Scopel says.
Seed Oils and Inflammation
One of the claims about seed oils is that they can contribute to chronic inflammation. Chronic, or long-term, inflammation raises the risk for a host of diseases, including type 2 diabetes, heart disease and dementia.
Some studies have shown that omega-6 fatty acids might increase inflammatory processes in the body. Yet other studies have found a diet high in omega-6s might reduce inflammation. And a recent study found that swapping out butter for plant-based oils, including canola oil, was linked to a reduced risk of dying from heart disease, cancer or other causes.
Another criticism of seed oils comes from the way they’re made. The seeds sometimes go through a chemical process to extract their oils. Some critics argue that toxic byproducts might be left behind. But there’s no evidence that any trace residue is left in seed oils, or even that such residues would be harmful. “Based on extensive research, the benefits of omega-6s outweigh the risks,” Scopel says.
The Scoop on Seed Oils
Olive oil, rich in omega-3s, is still the star of heart-healthy diets like the Mediterranean diet. But sometimes, there are good reasons to reach for seed oils instead.
“Seed oils tend to have a higher smoke point, so they’re better for cooking things at high heat, like when you’re making a stir fry,” Scopel says. They can also be more affordable than olive oil.
Seed oils can be especially beneficial if you’re using them to replace unhealthy saturated fats—such as sautéing a piece of salmon in canola oil instead of butter. They can also add nice flavor variety. Dressing a salad with sunflower oil, for example, can be a tasty way to add healthy fats to your plate.
Eating a lot of ultra-processed or deep-fried foods made with seed oils, on the other hand, is not a healthy way to get your polyunsaturated fats. “As with most things,” Scopel says, “moderation is key.”
Reviewed by Brianna Scopel, RD, a registered dietitian at Henry Ford Health.
