Human body, like metals, will gradually oxidize in nature. Metal oxidation is such as iron to yellow rust, copper to patina and so on. The main culprit of human oxidation is not oxygen, but oxygen free radicals, a kind of active gene with unpaired electrons outside the nucleus. This kind of unpaired electron is easy to cause chemical reaction, damage DNA, protein and lipid and other important biological molecules, and then affect the membrane transport process
Oxygen free radicals can enhance the phagocytosis of leukocytes to bacteria and inhibit bacterial proliferation, which can enhance the body's ability to fight infection and immunity
that the function of various tissues and organs is damaged, leading to aging of the body.