There may be as many as 10,000 oxidative hits to DNA per cell per day in humans.12 The vast majority of these lesions are repaired by cellular enzymes. Those that are not repaired may progress toward neoplasia (the formation of cancer cells). Because of the continual bombardment of DNA and other tissues by free radicals, the body must obtain ample antioxidant supplies through the diet. Epidemiological studies support a protective role for dietary antioxidants by consistently reporting that populations who consume inadequate amounts of fresh fruits and vegetables are at a higher risk for cancer, heart disease, and other degenerative diseases.
Not only can free radicals initiate cancer, they can also facilitate cancer progression. And in fact, multiple human tumor cell lines have been reported to produce ROS (especially hydrogen peroxide) in vitro.14 Under normal circumstances, few cells other than immune cells produce hydrogen peroxide. Free radical production by tumor cells may help them mutate or display other malignant properties such as tissue invasion. For example, superoxide radicals have been reported to increase the invasive capacity of rat liver cancer cells in vitro. Read More
