Seed oils are industrial oils from soy, corn, canola, cottonseed, sunflower, safflower, and similar seeds, usually high in linoleic acid.

Peat's view

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Primary foods to remove from the pantry and fryer. Marketing as heart-healthy conflicts with the membrane-stability view. Butter and animal fats replace them for cooking.

Specialty high-PUFA oils

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Supplement and "health" oils that are still high-PUFA specialty products, not cooking foundations or metabolic fixes: borage oil and evening primrose oil (GLA-rich omega-6), hemp oil, and similar seed extracts. Same structural problem as pantry seed oils: unstable polyunsaturates. Prefer not expanding them into separate doctrine pages.

Adulteration of avocado and olive oil

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A processed food labeled "avocado oil" can still contain seed oil. A 2026 UC Davis study tested 54 avocado-oil-labeled processed foods (chips, mayonnaise, salad dressing) bought from California stores and online retailers in 2025-2026.[1] 89% of the products were inconsistent with authentic avocado oil: 93% of chips, 71% of mayonnaise (100% of U.S.-made mayonnaise), and 100% of salad dressings tested.[2] Olive oil products in the same study fared much better, 1 of 20 failed.

Genuine avocado and olive oil are mostly oleic acid (monounsaturated), with linoleic acid around 10% or less. The adulterated samples showed a diluted fatty-acid and sterol profile consistent with cutting in cheap seed oils (soybean, sunflower, canola), plus reduced cis-vaccenic acid, a second independent marker for seed-oil adulteration.[2] A "100% avocado oil" label on a processed food, especially chips, mayonnaise, and dressings, is not proof of an oleic-acid-dominant product.

Cooking oil fumes and lung cancer

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Heating seed oils to frying temperatures creates an airborne exposure, not just an ingested one. A meta-analysis of thirteen Chinese case-control studies (3,596 lung cancer cases, 6,082 controls) found long-term cooking oil fume exposure associated with roughly double the risk of lung cancer in nonsmoking women, with the highest risk in kitchens lacking a fume extractor.[3] The pooled studies were mostly traditional high-heat wok frying in Chinese households, so the size of the effect may not transfer directly to other cooking styles, but heated linoleic acid breaks down into reactive aldehydes and other oxidized fragments, the same class of compounds implicated in PUFA's other harms.

See also

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References

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  1. ↑ Wang, S. et al. "Authenticity of avocado and olive oils used as ingredients in commercially processed foods." Applied Food Research (2026). https://doi.org/10.1016/j.afres.2026.102389
  2. ↑ 2.0 2.1 "That avocado oil chip you're eating may not be made with pure avocado oil." UC Davis, July 15, 2026. https://www.ucdavis.edu/food/news/avocado-oil-chip-youre-eating-may-not-be-made-pure-avocado-oil
  3. ↑ Xue Y, Jiang Y, Jin S, Li Y. "Association between cooking oil fume exposure and lung cancer among Chinese nonsmoking women: a meta-analysis," Onco Targets Ther. 2016;9:2987-92. PMID 27284248.