Diet : Microbe interactions - ecosystem support

Recent metagenomic studies are confirming what pioneers in gut microbiology have long said, that diet:microbe interactions in the gut impact on human health and disease. The gut microbiota appear to regulate various physiological functions including host energy metabolism, immune homeostasis, and brain development and function. The gut microbiota produces a range of biologically active metabolites, not least, short chain fatty acids, small phenolic compounds derived from polyphenol metabolism, and, immunologically and neurologically active amino acid derivatives such as gamma-aminobutyric acid, serotonin and dopamine. Microbiota activities also control systemic tryptophan metabolism and peripheral concentrations of potentially harmful metabolites derived from choline and carnitine metabolism, notably the cardiotoxicant trimethylamine-N-oxide. The gut microbiota also determines the profile of bile acids returning to the liver through the enterohepatic circulation, important cell signalling molecules involved in various physiological functions, including host energy metabolism and immune function. Diet in large part regulates these important microbiota physiological services and dietary constituents, particularly the relative proportions of fermentable fiber and plant polyphenols on the one hand, and refined sugars, fat and animal protein, on the other, appear to critically determine the flux of either beneficial or potentially harmful metabolites from the gut. This presentation will discuss how diet regulates both the composition and metabolic output of the gut microbiota constituting, in effect, ecosystem support, not just for the gut microbiota, but for the greater human:microbe ecosystem as a whole