This is something I only learned recently and the information isn’t getting any better for seed oils (vegetable oils).
VEGETABLE oils are highly unstable.
When they interact with oxygen, they release neurotoxic, DNA mutating chemicals which are known to cause cancer (at least).
Recent improvements in measurement technology have now thrown a spotlight on the quantity of these chemicals released by normal use. And the results are truly terrifying.
Cheap vegetable oil made from seeds (canola, sunflower, corn, safflower, grapeseed, rice bran and soybean oils) is a new addition to the human diet. Unlike animal fats and oils made from fruit (olive, avocado and coconut oils), they’re very high in polyunsaturated fats and in particular something called an omega-6 fat.News Corp Australia
A recent study found that when seed oils containing these fats are heated at a normal cooking temperature (of 180 degrees celsius), they create highly toxic chemicals known to be involved in cancer causation.