We depend on oxygen for our survival, so thankfully we live in an oxygen-rich environment. But oxygen is a powerful molecule, capable of reacting with other molecules. Rust is a great visual example of oxidative damage that occurs as a result of an oxygen-metal reaction. Oxygen is also a powerful reactant inside your body. While it is essential for health, it is also capable of disrupting cellular function and impairing efforts towards health by generating excessive amounts of oxygen radicals resulting in oxidative damage.
Ultimately health has a great deal to do with balance.
One of these points of balance is the relative activity of free radicals and antioxidants. Free-Radicals and Antioxidants Free radicals are highly reactive molecules. As mentioned, it is more a question of balance and your body has many redundant methods for establishing an appropriate balance of free radical activity. Substances that fuel your body's capability of keeping free radical activity in check are called antioxidants. When these forces become unbalanced and free radical troops outnumber your antioxidant forces, health invariably suffers.