In other words, it depends whether the antioxidants you're taking are fighting against the good, normal oxidation in your body or the bad oxidation. "The devil's in the details in a lot of these things," says Andrew Shao of the Council for Responsible Nutrition, a trade association in Washington, D.C., representing supplement manufacturers. "If you were to take all the marketing at face value, you might think that the ideal situation is to have no oxidation whatsoever. That is not what you want. It's part of normal biochemistry, part of the immune system."
"Most [antioxidants] don't work alone," he adds. "They're not drugs."
Like Cook, Shao recommends a diet high in antioxidants and a healthy lifestyle that includes regular exercise. "That may run counter to what you see in some marketing," he says, although he refused to say which ads he meant.
Marketing also makes it difficult for consumers to know what they are getting. "Is the product on the shelf the same one that was studied in clinical trials?" Shao asks. For foods, the Food and Drug Administration (FDA) and the Federal Trade Commission monitor claims made on the label or in advertising, but "it very much depends on the strength and specificity of the language in the claim," he says. A product that claims "antioxidant support" will raise less ire than one that claims to lower the risk of a particular disease.
In any case, the research is clear: Large, carefully controlled studies and trials have consistently found no benefit to antioxidant supplements, says Alice Lichtenstein of Tufts University.* "You have to take the totality of the data, and that's what we normally do [in science]," she says. "Why are they popular? I don't know. Maybe because it sounds like the easy answer."
With reporting by Willa Austen Isikoff
* Note (7/7/08): This sentence has been modified since the original posting.