Ageing and free radicals.

Mammalian ageing is a universal phenomenon that is both obvious and inevitable, yet poorly understood, and under-researched at the molecular level. Numerous ageing theories have been proposed to explain the progressive and deleterious changes characteristic of ageing. One of the most popular of these is the 'free radical' theory of ageing, which proposes that ageing results from imperfect protection against tissue damage brought about by free radicals. Oxygen free radicals are constantly produced during aerobic metabolism, and certainly provide a universal mechanism for oxidative damage. However, a major obstacle to acceptance of the theory has been the poor record of antioxidants in prolonging the lifespan of small animals. Many other variables, such as genetic factors, temperature, activity and nutrition can affect lifespan, making it a highly complex multi-factorial process.