Do Free Radicals Cause Aging?

Maybe not:

Conventional wisdom has held for decades that free radicals cause aging, and that antioxidants, which squelch the reactivity of these highly reactive molecules, are a way to slow the process. But new work adds to a growing body of research that suggests the story is not so simple.

In the new study published in PLoS Biology, worms that made more free radicals or that were treated with a free-radical-producing herbicide actually lived longer than normal worms.

What's more, when the longer-lived mutant worms were given antioxidants, the effects were reversed, and the worms had a conventional worm lifespan. The finding flies in the face of the idea that antioxidants battle the effects of aging.

According to study author Siegfried Hekimi of McGill University in Montreal and others, what is emerging from this and other experiments is a view of free radicals -- or, more precisely, reactive oxygen species -- as a normal part of the body's stress response, with beneficial effects at certain levels. "Maybe the reason why free radicals and aging are correlated is because free radical production in the mitochondria (part of the cell) is a stress reaction to the damage of aging," Hekimi said. "The organism tries to counter with free radical production."