Antioxidants are chemical compounds or substance that inhibits oxidation of molecules. Although oxidation reactions are crucial for life, they can also be damaging.
Low levels of antioxidants, or inhibition of the antioxidant enzymes, cause oxidative stress and may damage or kill cells. Diets high in fruit and vegetables, which are high in antioxidants, promote health and reduce the effects of ageing however, most diets still require a daily antioxidant supplement to maintain sufficient levels.
Antioxidant supplementation is particularly important for those engaging in physical activity where increased oxygen consumption and production of oxidants results in damage that contributes to muscular fatigue during and after exercise.