What are antioxidants? We’ve all heard about antioxidants and how they’re good for our body. But what are they and how do they work? To understand the role and importance of antioxidants, we need to look at what oxidation and free radicals affect our bodies. The cells that help our body process food also produce waste substances, which are called Free radicals. “Oxidative stress” is what occurs when our bodies do not process or remove these free radicals fast enough.