More of a good thing isn’t always better. In fact, it may not be good at all. One of those counter-intuitive examples has been identified by researchers as the antioxidant paradox.
We’ve all heard that antioxidants are good. Our bodies use oxygen to convert food to energy, and in the process produce free radicals, those atomic and molecular enemies that are linked to aging, cancer and heart disease. To neutralize free radicals, our bodies generate antioxidants, and advertisers offer us a host of products that promise to boost antioxidant power. Paul A. Offit, MD, chief of the infectious diseases division of Children’s Hospital in Philadelphia, explains in a New York Times piece "Don't Take Your Vitamins" that anti-oxidant rich diets and supplements don’t necessarily make us healthier and may even have a negative impact. That’s probably because antioxidants are part of elaborate networks in our bodies that interact in intricate ways. And free radicals aren't always bad. It turns out people need free radicals to kill bacteria and eliminate new cancer cells, Dr. Offit writes, and antioxidant overload can throw our immune systems out of whack. Tufts University scientists say more research is needed to explore the function and promise of antioxidants.
Dr. Offit also reminds readers that while vitamin deficiencies can cause dreadful diseases, the quantity needed is not always certain, and experts disagree about whether we should take supplements or get the vitamins we need from a good diet. But aren’t supplements harmless? Dr. Offit says don’t count on it. He cites several studies in which people who took vitamin E and vitamin A supplements had greater risk of disease and shorter lives than people in the same studies who took placebos. In one study, he writes, 18,000 people at risk for lung cancer because of smoking or asbestos exposure were given vitamin A and beta carotene or a placebo. Investigators halted that study, he writes, upon learning that those who took the vitamins had a 46% higher risk of death from cancer.
For another example of both/and in bodily matters, consider the gut bacterium Helicobacter pylori. In 1982 scientists discovered H.pylori, not stress, caused gastritis and ulcers, and it has since been linked to stomach cancer. Regarded as a dangerous pathogen, the bacterium was targeted for extinction with antibiotics.
Martin Blaser, MD, chairman of the Department of Medicine and a professor of microbiology at New York University School of Medicine, wondered how an organism that has been with us for 200,000 years could survive if it did nothing but harm. A New Yorker story by Michael Specter describes Dr. Blaser’s research. He has studied H. pylori extensively, and now considers it endangered-ubiquitous at one time, it now inhabits only half the world’s population, and fewer than half of the people in Western countries have gut H. pylori. Dr. Blaser and colleagues found it does have an important role in human health. They discovered people who had H. pylori in their guts were far less likely to have had asthma as children than those who did not. They also found a strong relationship between absence of H. pylori and risk for obesity. The New Yorker story explains two stomach hormones, ghrelin, which triggers hunger, and leptin, which suppresses hunger when we are full, work together to regulate appetite. H. pylori lowers ghrelin level after a meal. Those who lack H. pylori may have a harder time managing their weight because the message to stop eating may not reach the brain. Dr. Blaser suspects the lack of H. pylori is a factor in increasing obesity and other modern ills.
Dr. Blaser stresses that whether H. pylori causes or protects against disease depends on context. The organism plays a part in healthy development and functioning from infancy through early adulthood, but by mid-life and later-when we become increasingly prone to such woes as stomach trouble and cancer-we’re better off without it.