Study gut bacteria promotes overweight

Intestinal bacteria can promote the development of obesity

01/10/2014

A special intestinal bacterium promotes the development of obesity. At least in mice, as a new study shows. It has been suggested that the Clostridium ramosum bacterium in a high-fat diet helps boost sugar and fat intake and allows the fat deposits to grow faster.

Faster growing fat pads
A new study concludes that the naturally occurring in the human intestine bacterium Clostridium ramosum promotes the development of obesity. At least in mice. The study suggests that this microbial species on a high-fat diet helps boost sugar and fat intake from the small intestine. The associated greater intake of energy-supplying nutrients allows the fat pad to grow faster. The team of scientists around Prof. Dr. med. Michael Blaut and Anni Woting of the German Institute of Human Nutrition (DIfE) published their results in „mBio®“, the „online open-access journal“ the „American Society for Microbiology“.

Mechanisms still largely unknown
The DIfE, a member of the Leibniz Association, is researching the causes of nutrition-related diseases. Obesity, diabetes, cardiovascular diseases and cancer are the research priorities. The work should help to develop new strategies for prevention, therapy and nutritional recommendations. In recent years, various studies have suggested that the bacterial strain of the company, which includes C. ramosum, can affect human body weight and promote obesity. In addition, studies in humans suggest that there is a relationship between this type of microbe and the onset of the metabolic syndrome, which is characterized by obesity, hypertension, insulin insensitivity of the body's cells and impaired lipid metabolism. However, it is still largely unknown which mechanisms underlie these observations.

Four weeks high fat diet
„To find out more about these mechanisms, we studied mice that were not colonized with mouse-specific intestinal bacteria, but specifically with bacterial species of the human gut“, explained study leader Michael Blaut. „Our goal was to help create new scientific foundations for strategies that prevent overweight people and their associated diseases“, added Anni Woting, first author of the study. The researchers studied three mouse groups vaccinated with different bacterial species. At the beginning of the study, microbiologists selectively colonized germ-free animals with certain types of bacteria that are found naturally in the human gut. During the following four-week high-fat diet, no apparent differences were seen in feed intake and feed digestion. In addition, the researchers found no signs of inflammatory processes in the body of the animals. However, they apparently observed that the two mouse groups populated with C. ramosum had significantly more body weight and body fat than mice without this bacterial species.

More than just a mechanism
In addition, further analyzes showed that the two mouse groups inoculated with C. ramosum increasingly produced transport proteins in their small intestine cells that play a role in the intake of grape and fructose or in the absorption of fatty acids. However, the scientists were unable to observe any other mechanisms in their model system that favor obesity and have already been described in other studies. For example, such mechanisms include increased bacterial production of short-chain fatty acids, which could also serve as an energy source for the mice. „We therefore assume that there is more than one mechanism by which intestinal bacteria can contribute to the development of obesity“, so blue. It is also surprising that even a single bacterial species show such a strong effect, the microbiologist continues.

Many questions are open
The DifE researchers want to continue exploring the relationships between diet, microbiota and overweight in the future, as many questions remain open. One question that arises is why the observed effects were observed only under a high-fat diet and not under a low-fat, as control studies of the scientists revealed. Many other researchers also deal with microorganisms that colonize humans and especially the intestine. Thus, many insights were gained regarding the influence of the intestinal flora on health. Therefore, many experts also advise to rebuild the intestinal flora in order to help strengthen the immune system. (Ad)