peroxide ions are most damaging, another reason to skip out on vegetable oils, they have a lot of deodorizers which can mask their rancidness. Pure EVOO, coconut oil, butter, ghee, avocado oil, sesame seed oil, hemp seed oil, all can go rancid if not stored properly, or adulterated. If your oil is tangy or has that tingly aftertaste, throw it out. Good oil goes down smooth.