GI bacteria linked to obesity in mice studies

In the April issue of Mayo Clinic Proceedings, researchers from the USA's Mayo Clinic Arizona and Arizona State University suggest that the mix of the trillions of bacteria that populate the human gastrointestinal tract - gut microbiota - are involved in regulating weight and that modifying them could one day be a treatment option for obesity.

One study cited by the authors observed that young, conventionally-reared mice have significantly higher body fat content than a laboratory-bred, germ-free strain of mice that lack these bacteria, despite consuming less food than their germ-free counterparts. When gut microbiota from normal mice were transplanted into germ-free mice, they experienced a 60% increase in body fat within two weeks, without any increase in food consumption or differences in energy expenditure. Another animal study reviewed by the authors focused on the gene content of the gut microbiota in mice. Finding more end products of fermentation and fewer calories in the feces of obese mice led researchers to speculate that the gut microbiota in the obese mice help extract additional calories from ingested food.