TikTokers have been harping on about toxic seed oils for a while now, with several prominent health influencers claiming that they’re highly inflammatory. Is there any truth to their claims? Here’s what the science says about seed oils and why they aren’t as bad for you as you might think.
If you’re feeling a bit confused about seed oils like canola, sunflower, and soy oil, you’re not alone. Once lauded for their abundance of unsaturated fats, seed oils have been dubbed as toxic and inflammatory by a growing group of health influencers. But is their any evidence to substantiate their claims or are seed oils another victim of the TikTok rumor mill? There’s a lot to unpack here so let’s dig in.
What Are Seed Oils?
Seed oils are derived from the seeds of plants and include commonly used oils such as canola, safflower, sunflower, sesame, and peanut oil. These oils are found in kitchens, restaurants, and processed foods worldwide due to their versatility and relatively low cost. Although the exact nutrition composition varies depending on the oil, non-tropical seed oils are rich in polyunsaturated and monounsaturated fats and low in saturated fat and have traditionally been considered heart healthy.
Are seed oils bad for you?
The controversy surrounding seed oils primarily stems from two concerns 1) the use of hexane in the oil extraction process and 2) the presence of polyunsaturated omega-6 fatty acids, specifically linoleic acid.
Hexane Explained
Hexane is a chemical solvent often used in the extraction process of seed oils. When inhaled as a gas in high amounts, hexane can be toxic to humans, posing risks to factory workers exposed to it in poorly ventilated areas. However, exposure to trace amounts of hexane in food has not been proven harmful to health [1].
Moreover, not all seed oils use hexane in the extraction process. Cold-pressed and expeller-pressed oils use mechanical methods to separate the oil from the raw material, omitting the hexane altogether. So, arguing that seed oils are toxic on the basis of hexane, doesn’t hold much water.
Omega-6 Fatty Acids: The Facts
Omega-6 fatty acids, particularly linoleic acid, are abundant in seed oils and another point of contention among influencers who claim they are toxic. In theory, metabolites of omega-6 fat such as linoleic acid are pro-inflammatory, however, this is not consistent with the evidence from clinical and population studies [2]. On the contrary, some evidence suggests that saturated fat with unsaturated fats such as omega-6s can help reduce your risk of heart disease and diabetes [3].
The science gets less positive when omega-6s are compared against omega-3 fats, which are well-known for their inflammation-fighting capacity.
Population studies indicate that a high omega-6 to omega-3 ratio in your diet is associated with an increased risk of dying from all causes, cancer, and cardiovascular disease [4]. This doesn’t mean that omega-6 are bad but omega-3 fats are better, and underscores the importance of incorporating omega-3 fats throughout the week.
Tips for choosing and cooking with oils
Seed oils are not the villains they are sometimes made out to be. However, it makes sense to incorporate them alongside omega-3 fats and other sources of fat with known health benefits such as extra virgin olive oil and avocado oil.
Here are my recommendations for buying and choosing oils:
- Opt for cold-pressed oils: Cold-pressed oils use mechanical methods to separate the oil from the raw material, resulting in less nutrient loss than other extraction methods such as expeller-pressed and solvent extraction. (Expeller-pressed uses mechanical methods and heat to extract oils).
- Incorporate omega-3s often: Omega-3-rich foods like salmon, sardines, walnuts, and flaxseeds help improve your omega-6 to omega-3 ratio, promote heart health, and fight inflammation. Omega-3 fats are widely under-consumed, and a few more servings a week can go a long way!
- Avoid overheating seed oils or reusing them: High temperatures can lead to the formation of harmful compounds such as polycyclic aromatic hydrocarbons (PAHs) and certain seed oils like pumpkin seed oil are particularly susceptible to these changes [5]. Cook low and slow to minimize the formation of PAHs and other harmful compounds.
- Don’t forget about old stand-bys like extra virgin olive oil and avocado oil. Both these oils have known health benefits and a variety of applications.
The Bottom Line
Seed oils aren’t the villains they’re made out to be. Nevertheless, it makes sense to incorporate other sources of unsaturated fat such as extra virgin olive oil, rather than relying solely on seed oils for cooking. Omega-6 fats may not have the inflammation-fighting strength of omega-3s but that doesn’t make them toxic.
Hungry for more nutrition tips? Find them here.
References
[1] Cravotto, C., Fabiano-Tixier, A. S., Claux, O., Abert-Vian, M., Tabasso, S., Cravotto, G., & Chemat, F. (2022). Towards Substitution of Hexane as Extraction Solvent of Food Products and Ingredients with No Regrets. Foods (Basel, Switzerland), 11(21), 3412. https://doi.org/10.3390/foods11213412
[2] Su, H., Liu, R., Chang, M., Huang, J., Jin, Q., & Wang, X. (2018). Effect of dietary alpha-linolenic acid on blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. European journal of nutrition, 57(3), 877–891. https://doi.org/10.1007/s00394-017-1386-2
[3] Petersen, K. S., Maki, K. C., Calder, P. C., Belury, M. A., Messina, M., Kirkpatrick, C. F., & Harris, W. S. (2024). Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat. The British journal of nutrition, 1–12. Advance online publication. https://doi.org/10.1017/S0007114524002459
[4] Zhang, Y., Sun, Y., Yu, Q., Song, S., Brenna, J. T., Shen, Y., & Ye, K. (2024). Higher ratio of plasma omega-6/omega-3 fatty acids is associated with greater risk of all-cause, cancer, and cardiovascular mortality: A population-based cohort study in UK Biobank. eLife, 12, RP90132. https://doi.org/10.7554/eLife.90132
[5] Ganesan, K., & Xu, B. (2020). Deep frying cooking oils promote the high risk of metastases in the breast-A critical review. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 144, 111648. https://doi.org/10.1016/j.fct.2020.111648
