Gut bacteria may contribute to obesity

A new animal study has revealed that a species of gut bacteria called Clostridium ramosum, coupled with a high-fat diet may be contributing to obesity.

A research team from the German Institute of Human Nutrition Potsdam-Rehbruecke in Nuthetal observed that mice harboring human gut bacteria including C. ramosum gained weight when fed a high-fat diet. Mice that did not have C. ramosum were less obese even when consuming a high-fat diet and mice that had C. ramosum but consumed a low-fat diet also stayed lean.

Michael Blaut, PhD, head of the institute's Department of Gastrointestinal Microbiology, said that previous studies have found C. ramosum and other representatives of the Erysipelotrichi class in obese humans and the study suggested that growth of this organism in the digestive tract was stimulated by high-fat diets, which in turn improves nutrient uptake and enhances the effect of such diets on body weight and body fat.

Associations between obesity and increased levels of lipopolysaccharides (components of the cell wall of gram-negative bacteria) causing inflammation, or increased formation of molecules called short chain fatty acids, reported by other researchers, were not found in this study, which could possibly mean that there are more than one mechanism underlying the promotion of obesity by intestinal bacteria, he further added.

The study is published in mBio, the online open-access journal of the American Society for Microbiology.