Free radicals and antioxidants - quo vadis?

The field of free radicals and antioxidants, or 'redox biology', is fundamental to aerobic life. Aerobes constantly make reactive species, but modulate their actions by synthesizing antioxidants. This balance allows some reactive species to perform useful functions while minimizing oxidative damage. In general, dietary antioxidants are ineffective at modulating the 'redox balance' in humans. This helps to explain why, although oxidative damage contributes to the development and pathology of several human diseases, dietary 'antioxidant' supplements have limited efficacy in disease prevention. Cell culture as usually performed imposes oxidative stress upon cells, which can lead to artefactual data in studies of the roles of reactive species and the actions of added antioxidants in cultured cells. This brief commentary highlights in broad terms the current status of the redox biology field and the major challenges it faces in the next decade.