Oxidative stress is caused by an imbalance between the production of reactive oxygen species and the ability of the biological system to readily detoxify the reactive intermediates or quickly repair the resulting damage. All forms of life maintain a reducing environment within their cells which is preserved by enzymes that maintain the reduced state through a constant input of metabolic energy. Disturbances in this normal redox state can cause toxic effects through the production of peroxides and free radicals that damage all components of the cell, including proteins,lipids, and DNA. Humans are exposed to free radicals in the environment through smoking and by exposure to radiation and pollution. Free radicals are also produced naturally in the body through various metabolic reactions. In humans, oxidative stress or free radicals are involved in many diseases including atherosclerosis, Parkinson's disease, heart failure, myocardial infarction, Alzheimer's disease and fragile X syndrome [1].