Measuring the metabolic output of the human gut microbiota: implications for chronic disease risk

Recent metagenomic studies have highlighted significant associations between dysregulation of the intestinal microbiome and chronic disease risk in humans. Indeed, many diet and life-style associated diseases, obesity, type 2 diabetes, autoimmune diseases and certain cancers, all appear to possess characteristic profiles of gut bacteria and dysbiosys at the genetic level, with differences both in microbial diversity and relative abundance of important groups of gut bacteria compared to healthy individuals. However, clear links between aberrant microbiota composition and disease mechanisms in the host remain elusive. This presentation will focus on metabolic links between host and microbiome, metabolic links which appear to be altered in disease states and which in turn appear to be modifiable through dietary intervention. Interactions between specific dietary components, e.g. fermentable fibers/prebiotics, polyphenols and aromatic amino acids, appear to strongly influence both the composition and metabolic output of the gut microbiota and modify metabolites of known importance in physiological pathways regulating host metabolism and immune function. Similarly, high resolution MS based metabolomics is presenting a detailed picture of host:microbiome co-metabolism of many complex dietary components, providing novel biomarkers of intake and new putative therapeutic targets. Using data from model systems and human dietary interventions, the ability of host:microbiota co-metabolism to impact significantly on the risk of metabolic disease will be discussed using examples combining microbiome 16S rRNA sequence based profiling and biofluid targeted and untargeted MS based metabolomics.