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Definition of Free Radicals


Updated April 04, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Definition: Free radicals are atoms or molecules that have an odd number of electrons. Free radicals are unstable and roam the body in search of electrons to balance themselves. In the process, they create more free radicals out of the molecules they "steal" electrons from. Inhaled toxins in cigarette smoke create an abundance of free radicals.

Free radicals cause damage to cells and DNA, and are associated with creating an environment within the body that may contribute to chronic diseases such as cancer and heart disease.

See also: Smoking and Vitamin Depletion

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