The free radical theory of ageing

Abstract

The free radical theory of ageing hypothesizes that ageing is a consequence of incomplete inactivation of certain harmful toxins (called reactive oxygen species, or ROS) by the defence systems of the body. ROS are produced by the body as a direct consequence of its need for oxygen to survive. They are produced either accidentally, in the process of energy production, or deliberately, to annihilate bacteria and viruses. ROS produced in excess damage cell membranes, proteins and even DNA. It is hypothesized that the damage cannot always be reversed and hence causes the deterioration seen in the body during ageing.