Fighting Obesity with Bacteria

Intestinal bacteria from lean humans can confer protection against fat gain in experimental mice. [Also see Research Article by Ridaura et al.] The human large intestine harbors a complex community of microorganisms (microbiota) that affect many aspects of our physiology and health (1). Numerous lines of evidence, particularly from rodent models, have suggested that the intestinal microbiota may play a role in the development of obesity. On page 1241214 of this issue, Ridaura et al. (2) demonstrate that the microbiota from lean or obese humans induces similar phenotypes in mice and, more remarkably, that the microbiota from lean donors can invade and reduce adiposity gain in the obese-recipient mice if the mice are fed an appropriate diet.