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vegetable oils are the worst type of food known to manactually, there is no evidence that the commonly consumed vegetable seed oils such as sunflower, corn, canola, soy, peanut, safflower, cottonseed, walnut, linseed, etc., are harmful at all, except when rancid, trans, or hydrogenated. there was a long period when they were believed to be harmful simply because they were fats, but we now know that was wrong
there's a lot of old research where they were conflated with high-trans-fat-content partially-hydrogenated versions of themselves, and we now know that the trans fats were the major problem there. there was a period when it was believed that low ω-3 fatty acid levels relative to ω-6 levels were causing inflammation, and some people do see improvements in health when they eat more ω-3, but both ω-3 and ω-6 fatty acids are unsaturated fatty acids of the kind you find predominantly in vegetable seed oils; that's not a question of eating more or less seed oils but of which ones you eat. (and the ω-3 effect turned out to be fairly small on a population level.)
finally, there's a certain fanatical contingent that is convinced that unsaturated fatty acids in general (seed oils, fish oil) are terrible, and saturated fat (coconut oil, beef) is what's good for you, but this is basically completely unsupported by the evidence. a and there's a mountain of evidence against it. see https://slatestarcodex.com/2020/03/10/for-then-against-high-... for a deeper dive