The claimEvidence B · meta-analysis
Seed oils (omega-6) are toxic, inflammatory, fattening
The evidence
There is no human evidence for it. Replacing saturated fat with polyunsaturated fat lowers coronary heart disease (Mozaffarian 2010); the appetite idea has only been shown in mice (Alvheim 2012). The real issue is the fried, packaged form of the food, not the molecule.
The mechanism, in brief
Start with the heart: this is where the omega-6 argument has the most evidence, and the conclusion may not match either camp.
Sources (2)
- Mozaffarian, D., Micha, R., & Wallace, S. (2010). Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Medicine, 7(3), e1000252. Replacing saturated fat with polyunsaturated fat reduced CHD events ~19% (RR 0.81, 95% CI 0.70-0.95), ~10% per 5% energy.
- Hooper, L., Al-Khudairy, L., Abdelhamid, A. S., Rees, K., Brainard, J. S., Brown, T. J., et al. (2018). Omega-6 fats for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, (11), CD011094. Increasing omega-6 fats made little or no difference to cardiovascular events or mortality (low-certainty evidence), with a possible small reduction in myocardial infarction.