Antioxidants is a term referring to the function of a group of substances in combating Free Oxygen Radicals. Free Radicals are compounds that have an unopposed electrical charge due to electrons and that are highly reactive and unstable. They react with biological compounds in the body causing damage to living tissue.

They are normally produced in a variety of processes inside cells,and also by external processes including radiation, air pollution,cigarette smoking, heavy metals and drugs. Unopposed, Free Radicals can interact with the DNA in cells and destroy or alter the cell. These changes have been linked to the processes of ageing, cancer and certain chronic, degenerative and "auto-immune"diseases.

The body usually deals with Free Radicals using various enzyme systems, (some of which themselves require specific micronutrients) and specific vitamins, such as Vitamin C, Vitamin E and Vitamin A.