My husband and I are scheduling a short trip to visit friends this month. I’m a planner, which means I’ve been busy reading restaurant menus online and compiling a list of any that look promising for vegan dining. I wasn’t surprised to see that several restaurants boast that none of their dishes contain seed oils.  

It’s not my first personal run-in with the anti-seed oil crowd. At a recent gathering, a family member recoiled in absolute horror when I handed her a bottle of canola oil for a dish she was making. I couldn’t convince her that it was safe to use. Instead, she waited until she could get to the store to buy olive oil.  

Some evidence suggests that the anti-seed oil conspiracy originated with carnivore diet advocates who were platformed by conservative media. Notably, RFK, Jr, Donald Trump’s terrifying pick to lead the Department of Health and Human Services, avidly spreads anti-seed oil misinformation. He wants to replace the oils used in fast food restaurants with beef tallow. But wherever it started, the fear around seed oils has become so pervasive that no one group, political or otherwise, owns credit for it.

Commonly used seed oils include sunflower, safflower, soy, and corn oils, all of which are rich in linoleic acid, an essential omega-6 polyunsaturated fat. Canola is another seed oil although it is relatively low in linoleic acid and higher in monounsaturated fats.

Critics maintain that linoleic acid promotes inflammation through its conversion to the fatty acid arachidonic acid, thereby raising the risk for chronic diseases. This perspective is outdated. First, conversion of linoleic acid to arachidonic acid is limited and increased intake of linoleic acid has only negligible effects on blood or tissue levels.1  Intake of red meat is more likely to be associated with higher levels of arachidonic acid.2 Furthermore, arachidonic acid is converted to both inflammatory and anti-inflammatory compounds.1,3 So it’s not surprising that neither the clinical trials nor observational studies have linked linoleic acid consumption to inflammation in the body.4-8   

Seed oils are also criticized because of the processing required to extract oil from seeds. But what matters is how a food affects health, not whether it has undergone processing.  Contrary to the fearful discussion around seed oils and linoleic acid, there is abundant evidence that higher intake lowers risk for heart disease and possibly for type 2 diabetes.3,9-14 We also know – and have known for a long time – that replacing saturated fat in the diet with linoleic acid-rich fats like seed oils lowers blood cholesterol levels.15

It’s true that many highly processed foods are made with seed oils, but this has nothing to do with why some of these foods are unhealthful. Calorie-dense, sugary or salty foods made with lots of refined ingredients aren’t especially good for you regardless of the type of fat they contain. Adding seed oil to a processed snack food isn’t the thing that makes that food unhealthy. And Twinkies aren’t better for you than other snack cakes because they are made with beef tallow instead of canola oil.   

In my house, we use a lot of good quality extra-virgin olive oil, especially to dress salads or drizzle over cooked vegetables. I also use small amounts of oil for sauteing, and it’s usually some type of seed oil like soy or canola. I’ve yet to see any evidence-based reason why I should avoid these fats.

We should always push back against conspiracy theories aimed at discouraging harmless plant-based choices. The misinformation around seed oils is more than just annoying; it’s a real issue for veganism. It’s no big deal if manufacturers and restaurants start replacing soy oil with olive oil. It matters though, if they replace it with tallow and lard. Anything that drives up the demand for animal products harms animals and anything that shrinks the number of options for vegan dining hurts animals, too.

References

  1. Rett BS, Whelan J. Increasing dietary linoleic acid does not increase tissure arachidonic acid content in adults consuming Western-type diets: a systematic review. Nutr Metab (Lond) 2011;8:36.
  2. Seah JY, Gay GM, Su J, Tai ES, Yuan JM, Koh WP, Ong CN, van Dam RM. Consumption of Red Meat, but Not Cooking Oils High in Polyunsaturated Fat, Is Associated with Higher Arachidonic Acid Status in Singapore Chinese Adults. Nutrients 2017;9.
  3. Farvid MS, Ding M, Pan A, Sun Q, Chiuve SE, Steffen LM, Willett WC, Hu FB. Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies. Circulation 2014;130:1568-78.
  4. Su H, Liu R, Chang M, Huang J, Wang X. Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Food Funct 2017;8:3091-3103.
  5. Johnson GH, Fritsche K. Effect of dietary linoleic acid on markers of inflammation in healthy persons: a systematic review of randomized controlled trials. J Acad Nutr Diet 2012;112:1029-41, 1041 e1-15.
  6. Virtanen JK, Mursu J, Voutilainen S, Tuomainen TP. The associations of serum n-6 polyunsaturated fatty acids with serum C-reactive protein in men: the Kuopio Ischaemic Heart Disease Risk Factor Study. Eur J Clin Nutr 2018;72:342-348.
  7. Pischon T, Hankinson SE, Hotamisligil GS, Rifai N, Willett WC, Rimm EB. Habitual dietary intake of n-3 and n-6 fatty acids in relation to inflammatory markers among US men and women. Circulation 2003;108:155-60.
  8. Mazidi M, Gao HK, Vatanparast H, Kengne AP. Impact of the dietary fatty acid intake on C-reactive protein levels in US adults. Medicine (Baltimore) 2017;96:e5736.
  9. Jackson KH, Harris WS, Belury MA, Kris-Etherton PM, Calder PC. Beneficial effects of linoleic acid on cardiometabolic health: an update. Lipids Health Dis 2024;23:296.
  10. Amiri M, Raeisi-Dehkordi H, Sarrafzadegan N, Forbes SC, Salehi-Abargouei A. The effects of Canola oil on cardiovascular risk factors: A systematic review and meta-analysis with dose-response analysis of controlled clinical trials. Nutr Metab Cardiovasc Dis 2020;30:2133-2145.
  11. Karatzi K, Stamatelopoulos K, Lykka M, Mantzouratou P, Skalidi S, Zakopoulos N, Papamichael C, Sidossis LS. Sesame oil consumption exerts a beneficial effect on endothelial function in hypertensive men. Eur J Prev Cardiol 2013;20:202-8.
  12. Marangoni F, Agostoni C, Borghi C, Catapano AL, Cena H, Ghiselli A, La Vecchia C, Lercker G, Manzato E, Pirillo A, et al. Dietary linoleic acid and human health: Focus on cardiovascular and cardiometabolic effects. Atherosclerosis 2020;292:90-98.
  13. Wu JHY, Marklund M, Imamura F, Tintle N, Ardisson Korat AV, de Goede J, Zhou X, Yang WS, de Oliveira Otto MC, Kroger J, et al. Omega-6 fatty acid biomarkers and incident type 2 diabetes: pooled analysis of individual-level data for 39 740 adults from 20 prospective cohort studies. Lancet Diabetes Endocrinol 2017.
  14. Marklund M, Wu JHY, Imamura F, Del Gobbo LC, Fretts A, de Goede J, Shi P, Tintle N, Wennberg M, Aslibekyan S, et al. Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality. Circulation 2019;139:2422-2436.
  15. Schwingshackl L, Bogensberger B, Bencic A, Knuppel S, Boeing H, Hoffmann G. Effects of oils and solid fats on blood lipids: a systematic review and network meta-analysis. J Lipid Res 2018;59:1771-1782