title: Towards microbial fermentation metabolites as markers for health benefits of prebiotics.
abstract: Available evidence on the bioactive, nutritional and putative detrimental properties of gut microbial metabolites has been evaluated to support a more integrated view of how prebiotics might affect host health throughout life. The present literature inventory targeted evidence for the physiological and nutritional effects of metabolites, for example, SCFA, the potential toxicity of other metabolites and attempted to determine normal concentration ranges. Furthermore, the biological relevance of more holistic approaches like faecal water toxicity assays and metabolomics and the limitations of faecal measurements were addressed. Existing literature indicates that protein fermentation metabolites (phenol, p-cresol, indole, ammonia), typically considered as potentially harmful, occur at concentration ranges in the colon such that no toxic effects are expected either locally or following systemic absorption. The endproducts of saccharolytic fermentation, SCFA, may have effects on colonic health, host physiology, immunity, lipid and protein metabolism and appetite control. However, measuring SCFA concentrations in faeces is insufficient to assess the dynamic processes of their nutrikinetics. Existing literature on the usefulness of faecal water toxicity measures as indicators of cancer risk seems limited. In conclusion, at present there is insufficient evidence to use changes in faecal bacterial metabolite concentrations as markers of prebiotic effectiveness. Integration of results from metabolomics and metagenomics holds promise for understanding the health implications of prebiotic microbiome modulation but adequate tools for data integration and interpretation are currently lacking. Similarly, studies measuring metabolite fluxes in different body compartments to provide a more accurate picture of their nutrikinetics are needed.
authors.affiliation: Translational Research in Gastrointestinal Disorders (TARGID), KU Leuven and Leuven Food Science and Nutrition Research Center (LFoRCe),Leuven,Belgium.
authors.forename: Kristin A
authors.initials: KA
authors.lastname: Verbeke
authors.affiliation: Department of Medicine, Imperial College London,London,UK.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Boobis
authors.affiliation: Formerly ILSI Europe,Box 6, Avenue Emmanuel Mounier 83,BE-1200,Brussels,Belgium; now European Commission, Research Executive Agency (REA) Unit B2, Brussels, Belgium.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Chiodini
authors.affiliation: Human Nutrition School of Medicine, College of MVLS, University of Glasgow,Glasgow,Scotland.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Edwards
authors.affiliation: Cargill,Vilvoorde,Belgium.
authors.forename: Anne
authors.initials: A
authors.lastname: Franck
authors.affiliation: Host Microbe Interactomics, Wageningen University,Wageningen,The Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: Kleerebezem
authors.affiliation: FrieslandCampina,Amersfoort,The Netherlands.
authors.forename: Arjen
authors.initials: A
authors.lastname: Nauta
authors.affiliation: Microbiology and Immunology, Rega Institute, KU Leuven, Leuven; VIB, Leuven; DBIT, Vrije Universiteit Brussel,Brussels,Belgium.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Raes
authors.affiliation: Mead Johnson Nutrition,Nijmegen,The Netherlands.
authors.forename: Eric A F
authors.initials: EA
authors.lastname: van Tol
authors.affiliation: Nutrition and Nutrigenomics, Research and Innovation Centre-Fondazione Edmund Mach,Trento,Italy.
authors.forename: Kieran M
authors.initials: KM
authors.lastname: Tuohy
mesh_terms: D001419:Bacteria / Q000378:metabolism; D002241:Carbohydrates; D003106:Colon / Q000502:physiology; D005227:Fatty Acids / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000378:metabolism; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005285:Fermentation / Q000502:physiology*; D000069196:Gastrointestinal Microbiome / Q000187:drug effects; D006293:Health Promotion; D006801:Humans; D007422:Intestines / Q000382:microbiology*; D055432:Metabolomics; D056186:Metagenomics; D010944:Plants / Q000737:chemistry; D059808:Polyphenols / Q000378:metabolism; D056692:Prebiotics; D011506:Proteins / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D005227:Fatty Acids; D005232:Fatty Acids, Volatile; D059808:Polyphenols; D056692:Prebiotics; D011506:Proteins
keywords: Metagenome; Microbial metabolites; Nutrikinetics; Prebiotic health benefits