Saturday, March 06, 2010

gut bacteria cause overeating in mice

Wired | The connection between gut bacteria and obesity has gained some weight, with new findings demonstrating links in mice among immune-system malfunction, bacterial imbalance and increased appetite.

Mice with altered immune systems developed metabolic disorders and were prone to overeating. When microbes from their stomachs were transplanted into other mice, they also become obese.

“This supports the notion that some of the increase in obesity may be because of changes to gut bacteria,” said Andrew Gewirtz, an Emory University immunologist and co-author of the study, published March 4 in Science.

The findings are the latest in a growing body of research about the long-unappreciated role of bacteria in our bodies. Bacterial cells actually outnumber human cells in the body: From an outside perspective, people are not so much individual organisms as symbiotic human-bacteria collectives.

Disturbances to internal bacteria have been linked to asthma, cancer and many autoimmune diseases. Gut flora have also been linked to obesity. In 2006, researchers led by Washington University microbiologist Jeffrey Gordon documented bacterial changes in the stomachs of mice who became obese on high-fat diets.

When transplanted, their gut bugs turned other mice obese, suggesting that altered bacteria were not only an effect of weight gain, but a cause. The Science findings complement those, but also emphasize the immune system’s role and the possibility of appetite change.

“The reason why people are eating too much may not simply be because unhealthy food is cheap and available, but that their appetites may be driven by changes in gut bacteria,” said Gewirtz. Fist tap Dale.