Gut Microbiota Regulation of Tryptophan Metabolism in Health and Disease

Cell Host Microbe. 2018 Jun 13;23(6):716-724. doi: 10.1016/j.chom.2018.05.003.


The gut microbiota is a crucial actor in human physiology. Many of these effects are mediated by metabolites that are either produced by the microbes or derived from the transformation of environmental or host molecules. Among the array of metabolites at the interface between these microorganisms and the host is the essential aromatic amino acid tryptophan (Trp). In the gut, the three major Trp metabolism pathways leading to serotonin (5-hydroxytryptamine), kynurenine (Kyn), and indole derivatives are under the direct or indirect control of the microbiota. In this review, we gather the most recent advances concerning the central role of Trp metabolism in microbiota-host crosstalk in health and disease. Deciphering the complex equilibrium between these pathways will facilitate a better understanding of the pathogenesis of human diseases and open therapeutic opportunities.

Keywords: AhR; Crohn disease; IBD; autism; cerative colitis; gut microbiota; kynurenine; serotonin; tryptophan metabolism.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Autistic Disorder / metabolism
  • Autistic Disorder / microbiology
  • Colitis / metabolism
  • Communicable Diseases / metabolism
  • Crohn Disease / metabolism
  • Gastrointestinal Microbiome / physiology*
  • Gastrointestinal Tract / immunology
  • Gastrointestinal Tract / microbiology*
  • Gastrointestinal Tract / physiology
  • Humans
  • Indoles / metabolism
  • Inflammatory Bowel Diseases / metabolism
  • Kynurenine / metabolism
  • Metabolic Syndrome / metabolism
  • Metabolic Syndrome / microbiology
  • Obesity / metabolism
  • Serotonin / metabolism
  • Short Bowel Syndrome / metabolism
  • Short Bowel Syndrome / microbiology
  • Tryptophan / metabolism*


  • Indoles
  • Serotonin
  • Kynurenine
  • Tryptophan