Oxygen (or dioxygen, O2) is a gas essential to life. With the exception of some organisms, oxygen is essential to all animals, plants and bacteria in producing energy.
During evolution, living species adapting to oxygen resulted in the appearance of enzymes to help its consumption. During this process of cellular respiration, the body produces molecules that can be toxic. These molecules are called free radicals.
Free radicals are inevitable as they are produced daily during the body’s metabolism. The phenomenon is observable when an apple left in the open air turns brown, or when iron exposed to air and humidity turns to rust.
Oxidative damage due to an excess of free radicals are the major cause of cell senescence and aging. Although their excess must be controlled, their presence is nevertheless essential to stimulate cell repair and homeostasis mechanisms, especially in the defence against bacteria.
The body possesses a defence system to control these free radicals. There is a delicate balance between the production of free radicals and our body’s antioxidant defence system. It is for this reason that the cell can continue to function despite the formation of these free radicals.