Antioxidants, DNA damage and gene expression

Reactive oxygen species (ROS) are generated from incomplete reduction in th e respiratory chain. On one hand they pose a serious threat of deleterious effects on important macromolecules, among which DNA is considered most imp ortant since it carries the genetic information and changes will be carried on to future generations, or will fundamentally change the behaviour of th e tells. On the other hand, it is becoming evident that there are important changes in the cells in response to redox changes. This review summarises the genes, the intracellular signalling elements and molecules that present ly are known to be regulated by oxidative stress. It is now clear that both oxidants and antioxidants can regulate a multitude of different cellular f unctions, signal transduction pathways and gene expression. However, the qu antitative importance is unknown and as of vet there are no examples of reg ulation exclusively by oxidative stress. Also the response to oxidative str ess is variable, can be up-regulation as well as down-regulation, and diffe rent responses to dose or magnitude of the oxidative stress can be demonstr ated. The effect from supplementation with an antioxidant is difficult to p redict, and ultimately must be assessed in clinical trials.