Oxygen fuels the body's systems. In the process, byproducts - free radicals - are created that oxidize and break down tissues. An antioxidant is a molecule capable of inhibiting the oxidation of another molecule, breaking the free radical chain of reactions. Your body naturally circulates a variety of nutrients for their antioxidant properties. For example, vitamin C, vitamin E, carotenes, and lipoic acid are well-known and well-researched antioxidant nutrients.