This page has been folded into Dietary Fat.
Seed oils are not a fat type of their own — they are the n-6 polyunsaturated (linoleic acid) end of the same fat-type question, and their evidence sits alongside saturated, monounsaturated, n-3 and trans fat rather than apart from it. The seed-oil-specific material now lives in two sections of Dietary Fat:
- “The omega-6 inflammation claim, tested on its own terms” — the proposed omega-6 -> arachidonic-acid -> inflammation -> heart-disease pathway, tested on its own marker (Johnson: feeding linoleic acid does not raise CRP, IL-6, TNF-alpha or the other inflammatory markers; the LA -> AA conversion is minimal; arachidonic acid is not associated with higher cardiovascular risk). The mechanism is unsupported — which is not the same as seed oils being proven safe; a flat surrogate marker is as weak a proxy in either direction.
- “Seed oils: dose, composition, and the open questions” — the one bounded stratum flag (a concentrated, omega-6-selective oil at high dose after a heart attack, Sydney Diet Heart); the n-6-selective-versus-mixed-PUFA composition distinction (not an omega-6:omega-3 ratio target, which has no human-outcome evidence); the FADS1 genetic effect-modifier as a lead not a stratification; and the genuine gaps — heating, oxidation, extraction — held as insufficient-evidence, not as harm and not as a clean bill.
The short answer is unchanged: for a general-population eater, replacing saturated fat (butter, lard) with seed oils is the direction the evidence supports; there is nothing to gain from adding oil to a diet that already has enough fat; and this is a small lever well below the big rocks (smoking, body fat, activity). Provenance — “industrial”, “refined” — is not itself a health argument, in either direction.