Most seed-based oils contain a lot of linoleic acid, for example sunflower oil has 65%. It is an essential fatty acid, but the average consumption nowadays is way too high. It oxidizes easily which leads to health problems when too much of it is incorporated into cell and mitochondrial membranes.

Plant oils such as those from olive, coconut, palm, cocoa or avocado have much less linoleic acid.

Plant based oils often have low oxidation temperatures, and oxidized oils are not particularly healthy. Saturated fats usually have higher oxidation temperatures making them more suited to high temperature cooking.

Polyunsaturated fats have many unstable double carbon bonds, so especially under heat a wide range of new fat compounds form which were never present in the human diet.