The “Hateful Eight” Seed Oils: Separating Myth from Science

Seed oils, especially the so-called “hateful eight”: canola, corn, cottonseed, grapeseed, soy, rice bran, sunflower, and safflower, have become a hot topic in nutrition circles. Social media and pop culture have cast them as the latest dietary villains, prompting some restaurants to remove them from menus. But what does the science actually say?

The two main criticisms of seed oils are:

1. Omega-6 overload: Because seed oils contain more omega-6 than omega-3 fatty acids, some argue they promote chronic inflammation, chronic disease, and even obesity.
2. Processing concerns: These oils are highly refined, often using solvents like hexane, and some claim replacing them with butter or beef tallow is a healthier option.

Let’s unpack these claims.

Omega-6s Are Not the Enemy

It’s true that Americans consume far more omega-6s than omega-3s—according to Harvard Health about10 times more[1]. But both are essential fatty acids, meaning our bodies cannot produce them—we must obtain them from food. According to Harvard Health:

Omega-6 fatty acids lower LDL cholesterol (‘bad’ cholesterol) and reduce inflammation, and they are protective against heart disease. So, both omega-6 and omega-3 fatty acids are healthy. While there is a theory that omega-3s are better for our health than omega-6s, this is not supported by the latest evidence. Thus, the omega-3 to omega-6 ratio is basically the ‘good divided by the good,’ so it is of no value in evaluating diet quality or predicting disease.[1]

Christopher Gardner, director of nutrition studies at the Stanford Prevention Research Center, adds, “We’re eating more ultra-processed and fast foods than ever before. Those foods aren’t good for us, but there’s no evidence to suggest that seed oils are what makes them unhealthy.”[2] In other words, the problem isn’t the oils themselves—it’s the fried, calorie-dense, ultra-processed foods in which they’re commonly used.

A large, long-term study[3] tracking over 220,000 participants for up to three decades found that those who consumed the most plant-based oils, including olive and seed oils, had a lower overall risk of death. Replacing just two teaspoons of butter with plant-based oils each day was associated with a 17% reduction in premature mortality. Notably, the protective effects were consistent across individual oils such as canola, soybean, and olive oil.

What About Hexane and the Refining Process?

Hexane, a solvent commonly used to extract oils from seeds such as soybeans or canola, often sparks concern online. Peer-reviewed research shows that nearly all hexane is removed during the refining process. The trace amounts that remain (typically less than 1 milligram per kilogram of oil) are well below levels associated with any toxicity. Health risks from hexane exposure, such as neurotoxicity, occur with long-term inhalation in industrial settings, not from eating foods made with refined oils. Both the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) have reviewed the evidence and concluded that trace residual hexane in edible oils poses no safety concern for consumers.[4] If you prefer to avoid refined oils, organic and cold-pressed seed oils aren’t extracted with hexane or other chemical solvents. Because they’re less refined, these oils are more prone to oxidation and rancidity, so it’s best to store them in a cool, dark place or in the refrigerator for extra protection.

The Takeaway

If you want to reduce seed oil intake, focus on cutting fried and ultra-processed foods rather than villainizing the oils themselves. Whole-food dietary patterns that emphasize plant-based unsaturated fats from extra virgin olive oil and seed oils consistently show reductions in chronic disease risk.

A drizzle of olive oil on salad or a seed oil for roasted vegetables is a far better choice than frying French fries in beef tallow or reaching for an ultra-processed snack labeled “made without seed oils.” As Gardner notes, “In a situation where you need some kind of fat for cooking or food preparation, you can use plant oils or you can use butter or lard. Very consistently, all the data say butter and lard are bad for our hearts. And studies show swapping out saturated fats and replacing them with unsaturated fats lowers the risk for heart disease.”[5]

Ultimately, it’s not about focusing on a single ingredient: it’s about prioritizing whole, minimally processed, healthy dietary patterns.

1. Harvard Health Publishing. (2019, August 20). No need to avoid healthy omega-6 fats. Harvard Health. https://www.health.harvard.edu/newsletter_article/no-need-to-avoid-healthy-omega-6-fats
2. Callahan, A. (2024, November 9). Are seed oils actually bad for you? The New York Times. https://www.nytimes.com/2024/11/09/well/eat/seed-oil-effects.html
3. Zhang, Y., Chadaideh, K. S., Li, Y., Li, Y., Gu, X., Liu, Y., Guasch-Ferré, M., Rimm, E. B., Hu, F. B., Willett, W. C., Stampfer, M. J., & Wang, D. D. (2025). Butter and plant-based oils intake and mortality. JAMA Internal Medicine, 185(5), 549-560. https://doi.org/10.1001/jamainternmed.2025.0205
4. European Food Safety Authority (EFSA). (2010). Scientific opinion on hexane in food and feed. EFSA Journal, 8(4), 1074. https://doi.org/10.2903/j.efsa.2010.1074
   1. U.S. Food and Drug Administration. (2023). Guidance for industry: Residual solvents in drug products and components. https://www.fda.gov
   1. Zhu, H., & Damodaran, S. (2019). Hexane removal and safety evaluation in edible oil refining. Journal of the American Oil Chemists’ Society, 96(5), 567–578.
   1. Agency for Toxic Substances and Disease Registry (ATSDR). (1999). Toxicological profile for n-hexane. U.S. Department of Health and Human Services. https://www.atsdr.cdc.gov/toxprofiles/tp92.pdf
5. American Heart Association News. (2024, August 20). There’s no reason to avoid seed oils and plenty of reasons to eat them. American Heart Association. https://www.heart.org/en/news/2024/08/20/theres-no-reason-to-avoid-seed-oils-and-plenty-of-reasons-to-eat-them