Probiotic Hope and Hype

Despite their popularity, supplements with billions of "good" microbes help only a few illnesses, research shows

- BY LYDIA DENWORTH

THERE ARE MICROBES living in medicine cabinets across the U.S., next to the aspirin and the Band-Aids. And people want them there. Indeed, consumers probably paid good money for them.

Probiotics are capsules or pills with live microorganisms—almost always bacteria or yeast—that are supposed to confer health benefits once people swallow them. Some of my friends, including a woman who was recently treated for cancer and a man with persistent digestive issues, bought the pills at the recommendation of doctors. Others, aware of a lot of new evidence about the ways microbes in our guts influence physical functioning, bought them on their own. Many hope the bacteria will improve their overall gut health, a desire reflected in bottle labels that say things like “improved digestion” and “clinically studied.”

But despite this popularity, evidence that probiotics help people is surprisingly limited. Medical organizations such as the American Gastroenterological Association (AGA) recommend only a few specific bacterial strains for a few well-defined conditions. “The average person likely doesn’t need probiotics and is unlikely to benefit from them for day-to-day use,” says gastroenterologist Omeed Alipour of the Santa Clara Health System in California, a spokesperson for the AGA.