Does Cutting Out Seed Oils Make a Difference in Your Health?

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Seed oils like canola oil have been a hot topic on social media for years, with plenty of people claiming that they’re unhealthy.

While these oils aren’t perfect—they’re higher in a certain type of fatty acid that’s linked to inflammation, and overheating them could cause the formation of potentially harmful substances—the American Heart Association (AHA) says that they aren’t necessarily bad for you. And plenty of dietitians and doctors seem to agree.

So, what happens when you stop eating seed oils? Will you notice a difference or is it likely to be business as usual? And can one particular ingredient have that much of an impact on your overall health, or are all of the seed oil concerns overblown?

Like many things with nutrition, the answer is slightly complicated. With that in mind, here’s what you need to know about seed oils and their potential impact on your health, plus what can happen when you stop consuming them.

Meet the experts: Christopher Gardner, Ph.D., is a professor of medicine and nutrition scientist at Stanford University. Keri Gans, R.D.N., is the author of The Small Change Diet. Scott Keatley, R.D., is co-owner of Keatley Medical Nutrition Therapy.

What are seed oils?

Seed oils are extracted from the seeds of plants like soybean, sunflower, safflower, canola, and cottonseed, says Keri Gans, R.D.N., author of The Small Change Diet. “They’re high in polyunsaturated fats, especially omega-6 fatty acids,” she adds.

There are a lot of different seed oils, but some are more common than others. Here are some to have on your radar:

• Canola oil

• Corn oil

• Cottonseed oil

• Soybean oil

• Sunflower oil

• Safflower oil

• Grapeseed oil

• Rice bran oils

Worth noting: Olive oil and avocado oils are not seed oils.

Downsides of seed oils

There are a few reasons why seed oil is getting so much negative attention.

For one, they tend to have a high concentration of omega-6 polyunsaturated fats. Some people claim that the omega-6 fatty acids found in seed oil (particularly linoleic acid) can raise the risk of chronic inflammation. But the AHA says that omega-6 fatty acids can be a part of a healthy diet—they just may not be as healthy as omega-3 fatty acids.

And striking the right balance between the two is key: “Excessive omega-6 intake without adequate omega-3s may contribute to a pro-inflammatory state in the body, potentially exacerbating conditions like arthritis or cardiovascular disease,” says Scott Keatley, R.D., co-owner of Keatley Medical Nutrition Therapy. But as long as you’re eating enough omega-3-rich foods (such as fish, walnuts, and fortified yogurts) in general, and not going crazy with omega-6-rich foods, this shouldn’t be an issue, per Keatley.

There are a few other things to consider. “Overheating these oils past their smoke points may degrade them, leading to the formation of harmful compounds such as acrolein, aldehydes, and polycyclic aromatic hydrocarbons (PAHs),” Keatley says. “These substances may irritate the respiratory system, promote inflammation, and, with long-term exposure, potentially increase the risk of chronic diseases like cancer or cardiovascular issues.”

In case you’re not familiar with the term, a smoke point is the temperature at which an oil starts to smoke. Seed oils are known for their high smoke points, although the smoke points are different for each type. Safflower oil has a smoke point of 510°F, for example, while rice bran, sunflower oil, and soybean oil have smoke points of 450°F. You’ll see your oil start to smoke if you hit the smoke point, so it’s best to ditch it and start over with a lower level of heat if this happens to you.

It’s worth noting that olive oil, which has a smoke point of 325°F to 375°F, can also form harmful compounds like acrolein when it’s past its smoke point.

There are also concerns around phytoestrogen content in soybean oil. “These plant-based compounds are thought to mimic estrogen and potentially affect hormone levels,” Keatley says. But the phytoestrogens in soy “are significantly reduced or eliminated during the refining process of soybean oil,” he says. As a result, Keatley says that refined soybean oil contains “negligible amounts” of phytoestrogens and are unlikely to have any meaningful impact on hormone levels.

Should you stop eating seed oils?

The experts we spoke to say you don’t need to stop eating seed oils. “There is no conclusive evidence they’re harmful and avoiding them entirely isn’t necessary,” Gans says.

A lot of the potential issues with seed oils stem from what they’re used to cook, like fried foods, Keatley says. In general, it’s good to cut back on those—but it’s not just a seed oil thing, he says.

What happens when you stop eating seed oils?

It depends on what you replace them with, says Christopher Gardner, Ph.D., a professor of medicine and nutrition scientist at Stanford University. If you stop eating seed oils and don’t replace them with anything, you’ll likely lose weight “because you are now consuming fewer calories,” he points out.

If you swap your seed oil for olive oil, Gardner says it’s likely that “nothing” will happen since these oils are similar. But if you trade your seed oil for butter, lard, or beef tallow, Gardner says that your levels of LDL (aka “bad cholesterol”) may go up.

It also matters what you were eating your seed oil with, Gardner reiterates. “Were you eating seed oils like safflower oil as part of a salad dressing on salad?” he says. “Were you eating seed oils that were used in junk foods high in sugar and sodium?”

“With, what, and instead of what make all the difference,” he says. “[It] could be worse, better, or nothing.”

Gans agrees. “If your diet is already balanced, eliminating seed oils may not provide any additional value,” she says.

What can you swap for seed oils?

If you’re interested in cutting back on seed oils, Gans says that extra virgin olive oil is an “excellent choice” thanks to its polyphenols and monounsaturated fats. (Just bear in mind its lower smoke point.)

“However, using a variety of oils is key, and that can include seed oils, avocado, and nuts,” she says. “Each oil offers different nutrients, smoke points, and flavors, which can support a balanced diet.”

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