The refining process for seed oils can increase polymerized triglycerides and trans fats, but these are present in very low amounts (around 0.5%) and below thresholds for negative effects.

“um the the refining of vegetable oils seed oils is particularly problematic because of the types of fats they contain and I think you know the fact that we we couldn't eat these oils before modern industrial processing just shows how near impossible would have been to produce to consume high amounts of linoleic acid before modern industrial processing and you know there are plenty of studies showing that things like canola oil when they go through this high heat processing before they even go in the bottle a lot of those polyunsaturated fats actually turn into trans fats”