Free radicals are molecules generated by the breakdown of oxygen during metabolic activity. We all create a certain amount of free radicals through the very act of breathing,but normal levels do not pose a problem since the body’s defense mechanism is able to neutralize the molecules with antioxidants such as glutathione, ubiquinone, flavonoids, and vitamins A, E, and C. But when our antioxidant defenses are overwhelmed by too many free radicals, cells can be damaged and our health adversely affected. This is what is known as oxidative stress.