Diet and ageing: the possible relation to reactive oxygen species.

The hypothesis that the generation of reactive oxygen species (ROS) is the principal mechanism responsible for ageing, is reviewed in relation to the influence of diet and dietary factors on the generation of ROS and the effects on life span. Particular focus has been placed on the generation of ROS in the mitochondria, the effects this has on oxidative damage to cellular macromolecules, and the evidence that dietary factors can reduce this damage. Support for the hypothesis that the generation of ROS is a major causative factor in ageing depends on the demonstration that dietary factors, which are antioxidants, or which will reduce the rate of generation of ROS, will increase life span. The experimental evidence so far is not strong, apart from the consistent observation, across many species, that caloric restriction increases longevity. Proof that antioxidants are beneficial is mainly limited to the demonstration that they do increase average life span, principally through a reduction in the incidence of life-threatening diseases in animals, but there is little current evidence to support an increase in maximum life span. Since the experimental approach to date has been phenomenological, rather than mechanistically based, there is a need for further studies to be undertaken looking at specific mechanisms which are known to be influenced by antioxidants.