Hormesis and the antiaging action of dietary restriction.

Hormesis refers to the often encountered phenomenon of a beneficial biological action from a factor or agent that is generally viewed as detrimental. Beneficial actions that have been observed include life span extension. It is proposed that life span extension in rodents by dietary restriction is an example of hormesis and that sustained moderate hyperadrenocorticism underlies this life prolongation. Evidence supporting this concept is presented. The possibility is also suggested that whenever hormesis leads to an extension of mammalian life span, it is likely that moderate hyperadrenocorticism plays a major role.