antioxidant, substance that prevents or slows the breakdown of another substance by oxygen. Synthetic and natural antioxidants are used to slow the deterioration of gasoline and rubber, and such antioxidants as vitamin C (ascorbic acid), butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA) are added to foods (see food additives) to prevent them from becoming rancid or from discoloring.

In the body, nutrients such as beta-carotene (a vitamin A precursor), vitamin C, vitamin E, and selenium have been found to act as antioxidants. They act by scavenging free radicals, molecules with one or more unpaired electrons, which rapidly react with other molecules, starting chain reactions in a process called oxidation. Free radicals are a normal product of metabolism; the body produces its own antioxidants (e.g., the enzyme superoxide dismutase) to keep them in balance. However, stress, aging, and environmental sources such as polluted air and cigarette smoke can add to the number of free radicals in the body, creating an imbalance. The highly reactive free radicals can damage healthy DNA and have been linked to changes that accompany aging (such as age-related macular degeneration, a leading cause of blindness in older people) and with disease processes that lead to cancer, heart disease, and stroke.

Studies have suggested that the antioxidants that occur naturally in fresh fruits and vegetables have a protective effect. For example, vitamin E and beta-carotene appear to protect cell membranes; vitamin C removes free radicals from inside the cell. There is still some question as to whether antioxidants in the form of dietary supplements counteract the effects of increased numbers of free radicals in the body. Some scientists believe that regular consumption of such supplements interferes with the body's own production of antioxidants.

The Columbia Encyclopedia, 6th ed. Copyright© 2018, The Columbia University Press.

Antioxidants: Selected full-text books and articles

Beyond the 120-Year Diet: How to Double Your Vital Years By Roy L. Walford Four Walls Eight Windows, 2000 (Revised edition)
Librarian's tip: "Antioxidants" begins on p. 170
Controversies in Food and Nutrition By Myrna Chandler Goldstein; Mark A. Goldstein Greenwood Press, 2002
Librarian's tip: Chap. 11 "Antioxidants"
Antioxidants: Still Hazy after All These Years By Liebman, Bonnie Nutrition Action Healthletter, Vol. 32, No. 9, November 2005
The SkepDoc Antioxidants? It's a Bit More Complicated By Hall, Harriet Skeptic (Altadena, CA), Vol. 16, No. 4, Summer 2011
Antioxidant Supplementation Prevents Oxidation and Inflammatory Responses Induced by Sidestream Cigarette Smoke in Old Mice. (Articles) By Zhang, Jin; Jiang, Shuguang; Watson, Ronald R Environmental Health Perspectives, Vol. 109, No. 10, October 2001
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Antioxidants: No Magic Bullet By Liebman, Bonnie Nutrition Action Healthletter, Vol. 29, No. 3, April 2002
Role of Antioxidants in Generalised Anxiety Disorder and Depression By Gautam, Medhavi; Agrawal, Mukta; Gautam, Manaswi; Sharma, Praveen; Gautam, Anita; Gautam, Shiv Indian Journal of Psychiatry, Vol. 54, No. 3, July-September 2012
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Vitamin E-How Much Is Enough? By Emanoil, Pamela Human Ecology, Vol. 28, No. 2, Spring 2000
Food and You: A Guide to Healthy Habits for Teens By Marjolijn Bijlefeld; Sharon K. Zoumbaris Greenwood Press, 2001
Librarian's tip: "Antioxidants and the Role They Play" begins on p. 26
Bad Medicine: Misconceptions and Misuses Revealed, from Distance Healing to Vitamin O By Christopher Wanjek Wiley, 2003
Librarian's tip: Chap. 21 "Learning Your Alpha-Beta-Carotenes: Antioxidants, Pro and Con"
Coffee, Tea, Chocolate, and the Brain By Astrid Nehlig CRC Press, 2004
Librarian's tip: "Antioxidant Effects of Coffee" begins on p. 191
How Science Works: Evaluating Evidence in Biology and Medicine By Stephen H. Jenkins Oxford University Press, 2004
Librarian's tip: Chap. 2 "Do Vitamin C and Other Antioxidants Benefit Health? Using Observational and Experimental Studies to Test Medical Hypotheses"
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