Oxidative stress: from basic research to clinical application.

The occurrence of reactive oxygen species, known as pro-oxidants, is an attribute of normal aerobic life. The steady-state formation of pro-oxidants is balanced by a similar rate of their consumption by antioxidants that are enzymatic and/or nonenzymatic. "Oxidative stress" results from imbalance in this pro-oxidant-antioxidant equilibrium in favor of the pro-oxidants. A number of diseases are associated with oxidative stress, being the basis of antioxidant therapy. Current evidence in clinical research does not show unequivocal distinction between causal or associative relationships of pro-oxidants to the disease process.