The Microbiome in Obesity, Diabetes, and NAFLD: What is Your Gut Telling Us?

Abstract

The gut microbiota has considerable complexity and is influenced by multiple factors including host genetics and diet as well as metabolic diseases such as obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD). Despite animal studies demonstrating the gut microbiota may play a significant pathogenic role in these conditions, the exact mechanisms and host-bacterial interactions responsible remain cryptic. Reductions in the relative abundance of bacteria Clostridium leptum and coccoides groups, including Roseburia and Eubacterium spp. and Faecalibacterium prausnitzii, are implicated to protect against obesity and diabetes. The mucin-utilizing bacterium Akkermansia muciniphila has also been shown in animal models to have “protective” effects against obesity. Similarly, in animal and clinical studies of NAFLD, increased levels of Ruminococcus and Escherichia spp. have been documented, although their overall significance is unclear. Constraints in our understanding of cause- versus consequence relationships may be overcome in the future by utilizing “rationally designed” microbial consortia in small animal models.