The free radical theory has never been talked about more than it has been now. The reason? Free radicals multiply by the second and are practically all around our environment. But what really is the origin of this term, free radicals?
The free radical theory was coined by Denham Harman in 1950s. This theory explains the damage within the cells that are otherwise unexplainable. Here is what Wikipedia has to say about Free Radicals.
The free-radical theory of aging states that organisms age because cells accumulate free radical damage over time. A free radical is any atom or molecule that has a single unpaired electron in an outer shell. While a few free radicals such as melanin are not chemically reactive, most biologically-relevant free radicals are highly reactive. For most biological structures, free radical damage is closely associated with oxidative damage. Antioxidants are reducing agents, and limit oxidative damage to biological structures by passivating free radicals.
Strictly speaking, the free radical theory is only concerned with free radicals, but it has since been expanded to encompass oxidative damage from reactive oxygen species such as O2-,H2O2, or OH-.
Denham Harman first proposed the free radical theory of aging in the 1950s,[1] and in the 1970s extended the idea to implicate mitochondrial production of reactive oxygen species.[2]
In some model organisms, such as yeast and Drosophila, there is evidence that reducing oxidative damage does, as the theory would predict, extend lifespan. In mice, interventions that enhance oxidative damage generally shorten lifespan. Whether reducing oxidative damage below normal levels is sufficient to extend lifespan remains an open and controversial question.
