Antibiotics Could Be Driving Up Obesity

The human gut is home to a galaxy of bacteria thought to protect us from disease in the digestive tract and beyond. So what happens when we take antibiotics?

Sure, the pills can wipe out bad bacteria. But they also kill the good stuff. On top of fueling a rise in antibiotic-resistant superbugs, they could be permanently changing the gut environment — a feat some experts fear might be making us fat.

Dr. Martin Blaser of New York University Langone Medical Center studies the effects of antibiotics on Helicobacter pylori — a bacterium that lives quietly in most but leads to ulcers in some.

Although the majority of H. pylori infections are harmless, doctors are quick to treat them with antibiotics that change the way the stomach works.

“Antibiotics are miraculous,” Blaser told ABCNews.com in August after publishing an editorial on antibiotic overuse. “They’ve changed health and medicine over the last 70 years. But when doctors prescribe antibiotics, it is based on the belief that there are no long-term effects. We’ve seen evidence that suggests antibiotics may permanently change the beneficial bacteria that we’re carrying.”

Blaser discussed his latest research with the New York Times, explaining that antibiotics for H. pylori trick the body into eating more by disrupting hunger hormone levels. Indeed, mice given antibiotics get fatter than their untreated counterparts despite having the same diet, Blaser said.

The findings add weight to studies that have found differences in gut bacteria between lean and obese mice. Changes in gut bacteria – called the microbiome – could also be a risk factor for allergies, asthma and diabetes...