Polyunsaturated oils such as corn, soy, safflower and sunflower oils are hard-seed oils high in omega-6s and should be limited or avoided if possible. (Safflower and sunflower oils labeled high-heat or high oleic are exceptions ??? they???re primarily monounsaturated.) Polyunsaturates have more than one double bond, which break easily, and makes them more vulnerable to oxidation and degeneration.