Are Seed Oils Actually Bad for You?

Are seed oils toxic or harmful for your health? The answer depends on who you ask.

Spend any time watching health influencers on social media, and you might be convinced that these commonly used oils are downright poisonous. But that's a pretty far cry from the truth.

"When a headline is scary, such as 'seed oils cause inflammation,' it creates a black-and-white or right-or-wrong answer to a very nuanced subject," explains Asheville, North Carolina-based registered dietitian Katie Schwartz, RDN.

The fact is, seed oils aren't the nutritional demons they've been made out to be. But they're used in foods that tend to cause negative health effects, which in turn have given the oils a bad rap. Here's what you need to know about incorporating these fats into your diet.

Seed oils are oils that are extracted from the seeds of different plants. They're sometimes called vegetable oils. They include oils like:

• Canola
  
• Corn
  
• Cottonseed
  
• Grapeseed
  
• Rice bran
  
• Peanut
  
• Safflower
  
• Sunflower
  
• Soybean
  

Seed oils often show up in ultraprocessed foods, including things like deep fried foods, fast foods and packaged snacks, according to Massachusetts General Hospital. But you can also use them in home cooking and baking.

Seed oils are often criticized for being highly processed. And they can be, depending on how they're produced. The more common method involves extraction using high temperatures and pressure, often with chemical solvents to make them more heat stable, according to the Cleveland Clinic.

Alternately, seed oils can be cold-pressed, where the seeds are mechanically crushed to extract the oils without the use of chemicals. "Cold-pressed oils tend to retain more nutrients and have a different flavor profile but often come at a higher cost and have a shorter shelf life," explains Sue James, RDN, registered dietitian and owner of Pinnacle Health and Wellness LLC.

"The primary concern comes from overconsumption of processed foods rather than seed oils themselves."

The other concern is that seed oils are high in omega-6 fatty acids, a type of fatty acid that can increase inflammation, especially when eaten in large quantities. "The worry that seed oils cause inflammation is because seed oils contain something called linoleic acid, an omega-6, which the body can use to make an inflammatory compound called arachidonic acid," Schwartz says.

But this assumption hasn't born out in the research, Schwartz points out. Levels of arachidonic acid in the body don't decrease when people drastically slash their linoleic acid intake, according to an older review in ‌Nutrition & Metabolism‌. What's more, there's no research showing diets high in linoleic acid lead to inflammation in the body, per May 2012 research in the ‌American Journal of Clinical Nutrition‌.

So where does the inflammation connection come from? Many experts say it's not the seed oils themselves that are unhealthy, but rather, the foods that they tend to be used in — think: fried foods, baked goods, and packaged snacks, according to the Mayo Clinic. These foods "often contain high amounts of saturated fats, preservatives and additives that may contribute to inflammation," James says.

Despite claims you might've come across online, there's no evidence that seed oils themselves are bad for you. In fact, replacing saturated fats in your diet (like butter) with sources of polyunsaturated fats (like seed oils) can actually help protect against diabetes and heart disease, according to a July 2018 meta-analysis in the ‌Journal of Lipid Research‌.

That said, there's plenty of evidence that ultraprocessed foods ‌can‌ increase inflammation and raise your risk for chronic diseases. And reducing your reliance on these products can make a big difference in your health, per the Cleveland Clinic. "The primary concern comes from overconsumption of processed foods rather than seed oils themselves," James says.

Neither James nor Schwartz tells their clients to avoid seed oils. "The key to a healthy diet is consuming a variety of oils in moderation rather than focusing on eliminating a single type," James says. "When used appropriately, seed oils are not inherently more inflammatory than other oils."

Instead, make it a goal to eat more whole, minimally processed foods and fewer ultraprocessed ones. Not only will you automatically take in less seed oil, you'll slash your intake of other unhealthy fats, added sugars, sodium and additives and preservatives, according to the Harvard T.H. Chan School of Public Health.

When cooking at home, reach for a few different types of oils rather than just one. "Using a mix of oils ensures a more balanced intake of fats and essential nutrients," James says. Try canola oil for baking, olive oil for roasting and salad dressings and sesame oil for stir-fries, for instance.

Make it a point, too, to buy cold-pressed oils whenever you can. They tend to be a bit more expensive, but because they undergo less processing, they tend to have higher levels of antioxidant compounds, according to a December 2023 review in ‌Food Research International‌. They're also free of the chemical solvents used in oils that are heat-processed.

Just be sure to buy small quantities and store them in the refrigerator to keep them fresh. "They have a shorter shelf life," James says.

If you'd still rather steer clear of seed oils altogether, you've got plenty of alternatives to choose from. "I would recommend choosing oils high in monounsaturated fatty acids instead of ones that are high in saturated fats like coconut oil, because a diet high in saturated fat is shown to negatively affect heart health," Schwartz says. Oils rich in omega-3 fatty acids are a good choice too, James notes.

Solid options include:

• Olive oil
  
• Avocado oil
  
• Flaxseed oil
  
• Chia seed oil
  
• Walnut oil
  

Seed oils aren't the nutritional villains they're sometimes made out to be. If your goal is to prevent or reduce inflammation, focus on reducing your intake of ultraprocessed foods instead.