Is the Free-Radical Theory of Aging Dead? (preview)

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The hallowed notion that oxidative damage causes aging and that vitamins might preserve our youth is now in doubt

By Melinda Wenner Moyer

Image: THOMAS BORN Corbis

In Brief

• For decades researchers assumed that highly reactive molecules called free radicals caused aging by damaging cells and thus undermining the functioning of tissues and organs.
• Recent experiments, however, show that increases in certain free radicals in mice and worms correlate with longer life span. Indeed, in some circumstances, free radicals seem to signal cellular repair networks.
• If these results are confirmed, they may suggest that taking antioxidants in the form of vitamins or other supplements can do more harm than good in otherwise healthy individuals.

David Gems's life was turned upside down in 2006 by a group of worms that kept on living when they were supposed to die. As assistant director of the Institute of Healthy Aging at University College London, Gems regularly runs experiments on Caenorhabditis elegans, a roundworm that is often used to study the biology of aging. In this case, he was testing the idea that a buildup of cellular damage caused by oxidation?technically, the chemical removal of electrons from a molecule by highly reactive compounds, such as free radicals?is the main mechanism behind aging. According to this theory, rampant oxidation mangles more and more lipids, proteins, snippets of DNA and other key components of cells over time, eventually compromising tissues and organs and thus the functioning of the body as a whole.

Gems genetically engineered the roundworms so they no longer produced certain enzymes that act as naturally occurring antioxidants by deactivating free radicals. Sure enough, in the absence of the antioxidants, levels of free radicals in the worms skyrocketed and triggered potentially damaging oxidative reactions throughout the worms' bodies.

This article was originally published with the title The Myth of Antioxidants.

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