title: The Influence of Dietary Protein Intake on Mammalian Tryptophan and Phenolic Metabolites.
abstract: Although there has been increasing interest in the use of high protein diets, little is known about dietary protein related changes in the mammalian metabolome. We investigated the influence of protein intake on selected tryptophan and phenolic compounds, derived from both endogenous and colonic microbial metabolism. Furthermore, potential inter-species metabolic differences were studied. For this purpose, 29 healthy subjects were allocated to a high (n = 14) or low protein diet (n = 15) for 2 weeks. In addition, 20 wild-type FVB mice were randomized to a high protein or control diet for 21 days. Plasma and urine samples were analyzed with liquid chromatography-mass spectrometry for measurement of tryptophan and phenolic metabolites. In human subjects, we observed significant changes in plasma level and urinary excretion of indoxyl sulfate (P 0.004 and P 0.001), and in urinary excretion of indoxyl glucuronide (P 0.01), kynurenic acid (P 0.006) and quinolinic acid (P 0.02). In mice, significant differences were noted in plasma tryptophan (P 0.03), indole-3-acetic acid (P 0.02), p-cresyl glucuronide (P 0.03), phenyl sulfate (P 0.004) and phenylacetic acid (P 0.01). Thus, dietary protein intake affects plasma levels and generation of various mammalian metabolites, suggesting an influence on both endogenous and colonic microbial metabolism. Metabolite changes are dissimilar between human subjects and mice, pointing to inter-species metabolic differences with respect to protein intake.
authors.affiliation: Department of Microbiology and Immunology, Division of Nephrology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Ruben
authors.initials: R
authors.lastname: Poesen
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Physiology and Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands.
authors.forename: Henricus A M
authors.initials: HA
authors.lastname: Mutsaers
authors.affiliation: Translational Research for Gastrointestinal Disorders (Targid) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University of Leuven, Leuven, Belgium.
authors.forename: Karen
authors.initials: K
authors.lastname: Windey
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Petra H
authors.initials: PH
authors.lastname: van den Broek
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Vivienne
authors.initials: V
authors.lastname: Verweij
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, Drug Delivery and Disposition, University of Leuven, Leuven, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Augustijns
authors.affiliation: Department of Microbiology and Immunology, Division of Nephrology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Kuypers
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Physiology and Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Jitske
authors.initials: J
authors.lastname: Jansen
authors.affiliation: Department of Microbiology and Immunology, Division of Nephrology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
authors.affiliation: Translational Research for Gastrointestinal Disorders (Targid) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University of Leuven, Leuven, Belgium.
authors.forename: Kristin
authors.initials: K
authors.lastname: Verbeke
authors.affiliation: Department of Microbiology and Immunology, Division of Nephrology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Björn
authors.initials: B
authors.lastname: Meijers
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands; Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands.
authors.forename: Rosalinde
authors.initials: R
authors.lastname: Masereeuw
mesh_terms: D000328:Adult; D000818:Animals; D004032:Diet; D004044:Dietary Proteins / Q000494:pharmacology*; D004435:Eating / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D010636:Phenols / Q000097:blood / Q000378:metabolism* / Q000652:urine; D010865:Pilot Projects; D014364:Tryptophan / Q000097:blood / Q000378:metabolism* / Q000652:urine; D055815:Young Adult
chemical_list: D004044:Dietary Proteins; D010636:Phenols; D014364:Tryptophan