Antioxidants are chemical compounds that can bind to free oxygen radicals preventing these radicals from damaging healthy cells.

In early 2004, the National Cancer Institute (NCI) released a new fact sheet concerning cancer prevention and antioxidants. Fruits and vegetables are high in anti-oxidants and evidence continued to support the role of vitamins C, E, and A, as well as lycopene and beta-carotene in helping to prevent cancer. However, clinical trial results have not been consistent. The NCI reported that three large clinical trials were trying to better answer the role of antioxidants in cancer prevention.
Free radicals are naturally produced in the body through the normal metabolism of amino acids and fats. These free radicals are unstable molecules that can freely react with and destroy healthy cells. They can bind to and alter the structure of DNA thus leading to mutations and eventually to cancer. Besides cancer, this oxidative stress on the cells can lead to heart, eye, and neurological diseases.