Oxidative modification of biologically essential molecules by reactive oxygen and nitrogen species
(ROS/RNS) has been implicated in the pathogenesis of various diseases. At the same time, roles of
ROS/RNS as physiological signaling messenger have been established. Lipid oxidation products also
have two faces. It is argued that the radical scavenging antioxidants taken from diet or supplement
may impair such beneficial effects of ROS/RNS and lipid oxidation products. However, it is unlikely
that antioxidants impair physiologically important signaling, since the antioxidants do not scavenge
signaling ROS/RNS nor do they inhibit the formation of signaling molecules. Lipid peroxidation
products are not produced on purpose and inhibition of lipid peroxidation by antioxidants should
be beneficial for maintenance of health and reducing disease risk.