Are Seed Oils Bad for You?
I often hear this question from patients navigating health & wellness with both curiosity and caution: “Are seed oils bad?” It’s a fair concern—especially when social media headlines warn about “toxic oils” and urge you to toss every bottle of canola oil from your pantry.
But here’s the truth: seed oils are not inherently harmful for you—and when used wisely, they can support your heart and metabolic health.
The Case for Seed Oils
Let’s start with what we know. The American Heart Association recommends replacing saturated fats (like butter or coconut oil) with liquid plant oils—including seed oils like canola, sunflower, and safflower—to improve cardiovascular outcomes (Lichtenstein et al., 2021).
Seed oils are rich in polyunsaturated (PUFAs) and monounsaturated fats (MUFAs), which have been shown to reduce LDL cholesterol and cardiovascular disease risk (Voon et al., 2024).
But What About the Warnings?
Concerns about seed oils typically involve their chemical stability during cooking. Oils rich in polyunsaturated fats can break down into harmful compounds—like aldehydes—when exposed to high heat or prolonged light (Freis & Vemulapalli, 2025). Aldehydes are associated with increased cancer and neurodegenerative risk.
The cooking method matters: stir-frying with a stable oil is not the same as deep-frying at high heat. That’s why industrial food processing and ultra-processed snacks deserve more scrutiny than your sauté pan.
Are There Safer Alternatives?
Yes—and you likely already use them.
Olive oil, especially extra virgin, is high in MUFAs and consistently linked to lower cardiovascular risk and improved lipid profiles (Petersen et al., 2024).
Canola oil contains both MUFAs and alpha-linolenic acid (a plant-based omega-3) and is considered heart-healthy (Heymsfield & Shapses, 2024).
Camellia seed oil has shown benefits in improving liver enzymes and cardiometabolic markers in clinical trials (Wu et al., 2022).
Flaxseed oil is another excellent option for boosting omega-3s—just avoid using it for cooking due to its low smoke point.
Cooking temperature matters just as much as oil selection. Oils like rapeseed or canola generate fewer aldehydes during cooking compared to sunflower oil (Peng et al., 2017).
What About Omega-6s?
Omega-6s, particularly linoleic acid (LA), have drawn criticism for potentially contributing to inflammation. However, most high-quality studies show that moderate LA intake does not elevate inflammation markers (Visioli & Poli, 2025; Petersen et al., 2024). In fact, higher intake of omega-6 PUFAs is associated with lower risks of cardiovascular disease and type 2 diabetes (Marklund et al., 2019; Maki et al., 2018).
So where did the “inflammatory” label come from? LA is a precursor to arachidonic acid, which can be converted into pro-inflammatory eicosanoids. But in real-world diets, increased LA doesn’t reliably trigger this cascade.
Why the Omega-6/Omega-3 Ratio Matters
The problem isn’t omega-6s—it’s the imbalance between omega-6 and omega-3 intake. The typical Western diet contains a ratio as high as 20:1, which may promote chronic inflammation (Simopoulos, 2006; Simopoulos, 2008).
Omega-3s—like EPA and DHA found in fatty fish—create anti-inflammatory compounds and reduce cardiovascular and autoimmune risk (Djuricic & Calder, 2021; Saini & Keum, 2018).
A lower omega-6/omega-3 ratio is more desirable. You don’t need to fear LA—but you do need more EPA and DHA in your life.
What's the Ideal Ratio?
Experts suggest aiming for an omega-6/omega-3 ratio between 4:1 and 2:1 for optimal health (Simopoulos, 2002). For example:
A 4:1 ratio was associated with a 70% reduction in mortality in secondary prevention of heart disease (Simopoulos, 2008).
A 2–3:1 ratio was shown to suppress inflammation in rheumatoid arthritis (Simopoulos, 2006).
This can be achieved by:
Increasing your intake of omega-3-rich foods (e.g., salmon, sardines, flaxseed, walnuts)
Using omega-6-rich seed oils like corn or soybean oil in moderation
Choosing heat-stable, heart-healthy oils for cooking
Final Takeaway: Don’t Fear Seed Oils—Use Them Wisely
At Well Endocrinology, we believe your nutrition should reflect both evidence and lived experience. Seed oils aren’t “toxic,” but they shouldn’t dominate your diet either. Balance, variety, and thoughtful cooking matter far more than any single ingredient.
If you’re navigating high cholesterol, insulin resistance, or inflammation and wondering what fats are best for your body, we’re here to help. Together, we can create a science-backed plan that supports your long-term health goals.
References
Djuricic, I., & Calder, P. C. (2021). Beneficial outcomes of omega-6 and omega-3 polyunsaturated fatty acids on human health: An update for 2021. Nutrients, 13(7), 2421. https://doi.org/10.3390/nu13072421
Freis, A. M., & Vemulapalli, S. P. B. (2025). Analysis of the generation of harmful aldehydes in edible oils during sunlight exposure and deep-frying. Foods, 14(3), 513. https://doi.org/10.3390/foods14030513
Heymsfield, S. B., & Shapses, S. A. (2024). Guidance on energy and macronutrients across the life span. The New England Journal of Medicine, 390(14), 1299–1310. https://doi.org/10.1056/NEJMra2214275
Lichtenstein, A. H., Appel, L. J., Vadiveloo, M., et al. (2021). 2021 dietary guidance to improve cardiovascular health: A scientific statement from the American Heart Association. Circulation, 144(23), e472–e487. https://doi.org/10.1161/CIR.0000000000001031
Maki, K. C., Eren, F., Cassens, M. E., Dicklin, M. R., & Davidson, M. H. (2018). ω-6 polyunsaturated fatty acids and cardiometabolic health: Current evidence, controversies, and research gaps. Advances in Nutrition, 9(6), 688–700. https://doi.org/10.1093/advances/nmy038
Marklund, M., Wu, J. H. Y., Imamura, F., et al. (2019). Biomarkers of dietary omega-6 fatty acids and incident cardiovascular disease and mortality. Circulation, 139(21), 2422–2436. https://doi.org/10.1161/CIRCULATIONAHA.118.038908
Petersen, K. S., Maki, K. C., Calder, P. C., et al. (2024). Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat. The British Journal of Nutrition, 132(8), 1039–1050. https://doi.org/10.1017/S0007114524002459
Peng, C. Y., Lan, C. H., Lin, P. C., & Kuo, Y. C. (2017). Effects of cooking method, cooking oil, and food type on aldehyde emissions in cooking oil fumes. Journal of Hazardous Materials, 324(Pt B), 160–167. https://doi.org/10.1016/j.jhazmat.2016.10.045
Rimm, E. B., Appel, L. J., Chiuve, S. E., et al. (2018). Seafood long-chain n-3 polyunsaturated fatty acids and cardiovascular disease: A science advisory from the American Heart Association. Circulation, 138(1), e35–e47. https://doi.org/10.1161/CIR.0000000000000574
Saini, R. K., & Keum, Y. S. (2018). Omega-3 and omega-6 polyunsaturated fatty acids: Dietary sources, metabolism, and significance. Life Sciences, 203, 255–267. https://doi.org/10.1016/j.lfs.2018.04.049
Simopoulos, A. P. (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & Pharmacotherapy, 56(8), 365–379. https://doi.org/10.1016/s0753-3322(02)00253-6
Simopoulos, A. P. (2006). Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: Nutritional implications for chronic diseases. Biomedicine & Pharmacotherapy, 60(9), 502–507. https://doi.org/10.1016/j.biopha.2006.07.080
Simopoulos, A. P. (2008). The importance of the omega-6/omega-3 ratio in cardiovascular disease and other chronic diseases. Experimental Biology and Medicine, 233(6), 674–688. https://doi.org/10.3181/0711-MR-311
Visioli, F., & Poli, A. (2025). Omega 6 fatty acids: Helpful, harmless or harmful? Current Opinion in Clinical Nutrition and Metabolic Care, 28(2), 114–120. https://doi.org/10.1097/MCO.0000000000001096
Voon, P. T., Ng, C. M., Ng, Y. T., et al. (2024). Health effects of various edible vegetable oil: An umbrella review. Advances in Nutrition, 15(9), 100276. https://doi.org/10.1016/j.advnut.2024.100276
Wu, M. Y., Du, M. H., Wen, H., et al. (2022). Effects of n-6 PUFA-rich soybean oil, MUFA-rich olive oil and camellia seed oil on weight and cardiometabolic profiles among Chinese women: A 3-month double-blind randomized controlled-feeding trial. Food & Function, 13(8), 4375–4383. https://doi.org/10.1039/d1fo03759e
