The gut microbiome is the community of symbiotic bacteria which inhabits the gut, where it plays a role in digestion, metabolism and inflammation. The composition of this community varies from person to person, and has been found to play an important role in a variety of diseases, including obesity.
Here, researchers showed that when mice received gut microbiota transplants from obese humans, they gained weight and developed metabolic problems, despite being fed a lean diet. Conversely, mice receiving the gut microbes of lean humans remained lean. When the mice were kept together so that they would share their gut microbes, the lean-associated bacteria were able to colonise the guts of the other mice, but only when the recipients were fed a lean diet.
By identifying those bacteria specific to the guts of lean individuals, it should in principle be possible to transplant these microorganisms in order to treat or prevent metabolic disorders. This research also suggests that transplantation alone would not be enough: recipients would need to change their diet to support colonisation by the new bacteria.
“Eating a healthy diet encourages microbes associated with leanness to quickly become incorporated into the gut,” said senior author Jeffrey I. Gordon, MD, director of the Center for Genome Sciences & Systems Biology at Washington University. “But a diet high in saturated fat and low in fruits and vegetables thwarts the invasion of microbes associated with leanness. This is important as we look to develop next-generation probiotics as a treatment for obesity.”
“We think the lack of diversity leaves open niches – or jobs, if you will – that can be filled by microbes associated with leanness,” he said. “Our results underscore the strong interactions between gut microbes and diet and help illustrate how unhealthy diets select against gut microbes associated with leanness.”