Antioxidants are substances that can prevent or slow damage to cells caused by free radicals, unstable molecules that the body produces as a reaction to environmental and other pressures. They are sometimes called “free-radical scavengers.” Examples of antioxidants that come from outside the body include: vitamin A, vitamin C, vitamin C beta-carotene, lycopene, lutein, selenium, manganese, zeaxanthin, Flavonoids, polyphenols, and phytoestrogens are all types of antioxidants and phytonutrients, and they are all found in plant-based foods.