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Are Antioxidant Supplements Such as Vitamin C Harmful?

For related articles and more information, please visit OCA's Health Issues page and our Nutri-Con page.

Dr. Offit says yes. Our experts say no. Here's why.

Last month we told you about Dr. Paul A. Offit, who wrote a New York Times opinion piece and related book about the dangers of vitamin supplements. In the article, Dr. Offit writes, "When people take large doses of antioxidants in the form of supplemental vitamins, the balance between free radical production and destruction might tip too much in one direction, causing an unnatural state where the immune system is less able to kill harmful invaders."

Please note that Dr. Offit refers vaguely to "large doses," although in interviews he seems to oppose any antioxidant supplementation. But is his science right? Might, for example, antioxidant supplements increase the risk of cancer?

Two years ago we discussed a similar article on antioxidants published in Newsweek. You may recall that Dr. Jonathan Wright noted that Newsweek's view of antioxidants vs. oxidants was too simplistic: "When a molecule loses electrons, it has been 'oxidized'; when it gains electrons, it has been 'reduced.' Since one molecule's loss is always another molecule's gain, the oxidation/reduction must always occur simultaneously, and the whole electron-exchange transaction is called a 'redox reaction.' " He showed that it's not a straight reaction between "antioxidants" and "oxidizing agents." Instead, antioxidants work on both sides of redox reaction-sometimes donating electrons, and sometimes gaining them. Antioxidants are more accurately described as "redox reaction regulators," assisting on both sides of the electron subtraction ("oxidation") and addition ("reduction") equation.

Dr. Wright also pointed out that vitamins should always be taken with other substances. For example, taking beta-carotene in large quantities without the cofactors found in nature, such as other carotenoids, or taking vitamin E in the common alpha-tocopherol form without other tocopherols, especially gamma, is dangerous. Antioxidants occur in groups in nature, and this should always be considered when supplementing.