[Conclusions, future prospects and recommendations]

Understanding the notion of oxidative stress implies a good knowledge of the reactivity of the different reactive oxygen species (ROS). Cell damage can be induced by an overproduction of these species and/or by a deficiency in the protective antioxidant systems. Nevertheless, ROS do not display only deleterious effects and play key-roles in cell signalisation and regulation of the expression of redox sensitive genes. Besides ROS, reactive nitrogen species (RNS) with nitric oxide (*NO) as leader element, are widely involved in biology and lead to the term "nitrosative stress" that particularly describes the damage induced by peroxynitrite, a species formed by reaction between superoxide anion and degrees NO. Nutritional strategies have been based on antioxidant-rich diets, or on supplementation with antioxidants; they could constitute adjunct therapies of interest. Given all these data, radical biochemistry must be considered as a specific discipline.