Unfortunately there is a lot of hype on the dangers of free radicals, but you never hear of the benefits. The body generates some free radicals to benefit the body in different ways. The most important of these free radicals is hydrogen peroxide, which is generated by the enzyme superoxide dismutase in many cells to activate white blood cells. Some flora produce peroxide to kill bacteria and fungi. White blood cells, such as NK cells, generate peroxide to destroy pathogens and cancer cells.
Healthy cells use antioxidants and antioxidant enzymes (catalase, peroxidases, and superoxide dismutase) to protect themselves from the damaging effects of free radicals. Diseased cells, such as cancer cells and microbes often do not have these same defenses making them more vulnerable to attack by the free radicals produced by the body. There is a limited supply of antioxidants available to cells. Therefore, if the amount of free radicals present exceeds the body’s ability to neutralize the unnecessary free radicals then damage can occur.
On the flip side, taking excess levels of antioxidants can actually suppress the immune system by locking up beneficial free radicals like hydrogen peroxide.