The aging paradox: free radical theory of aging

Exp Gerontol. 1999 Jun;34(3):293-303. doi: 10.1016/s0531-5565(99)00005-4.


There are more than 300 theories to explain the aging phenomenon. Many of them originate from the study of changes that accumulate with time. Among all the theories, the free radical theory of aging, postulated first by Harman, is the most popular and widely tested, and is based on the chemical nature and ubiquitous presence of free radicals. This review aims to recapitulate various studies on the role of free radicals in DNA damage-both nuclear as well as mitochondrial-the oxidative stress they impose on cells, the role of antioxidants, the presence of autoantibodies, and their overall impact on the aging process.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aging / genetics
  • Aging / immunology
  • Aging / metabolism*
  • Animals
  • Antioxidants / metabolism
  • Autoantibodies / metabolism
  • DNA Damage
  • Free Radicals / metabolism
  • Humans
  • Models, Biological
  • Oxidative Stress
  • Proteins / metabolism
  • Reactive Oxygen Species / metabolism*


  • Antioxidants
  • Autoantibodies
  • Free Radicals
  • Proteins
  • Reactive Oxygen Species