Free Radical Shift; May 2009; Scientific American Magazine; by Kate Wilcox; 2 Page(s)

Companies have started putting antioxidants in goods as different as face creams and soda, claiming that they clean out cells, prevent cancer and even stave off death. The idea is to prevent unstable oxygen molecules, which are normal by-products of metabolism, from damaging cells. But a recent study suggests that when it comes to living longer, those antioxidants may not be the answer.

The antioxidant theory of aging states that some of the oxygen molecules used by the body become negatively charged, making them reactive. As a result, they compromise health and age the body by damaging cell structures, proteins and DNA. Cells have a natural defensesuperoxide dismutase (SOD), a special class of antioxidant that neutralizes the chemicals and prevents them from harming cells. According to the theory, proposed in 1956 by Denham Harman, now emeritus professor of medicine at the University of Nebraska, when the body gets older, SODs become less efficient at preventing oxidative stress. Over the past 50 years this widely accepted theory has held up in studies: when the SOD gene is knocked out in mice, flies or yeast, the organisms develop cancers and have shorter life spans.