Exploration of Associations Among Dietary Tryptophan, Microbiome Composition and Function, and Symptom Severity in Irritable Bowel Syndrome

Authors

Anna M Plantinga
Kendra J Kamp
Qinglong Wu
Li Chen
Linda Yoo
Robert L Burr
Kevin C Cain
Daniel Raftery
Fausto Carnevale Neto
Shyam Badu
Sik Yu So
Tor Savidge
Robert J Shulman
Margaret M Heitkemper

Publication Date

5-1-2023

Journal

Neurogastroenterology & Motility

DOI

10.1111/nmo.14545

PMID

36780542

PMCID

PMC10953042

PubMedCentral® Posted Date

5-1-2024

PubMedCentral® Full Text Version

Author MSS

Published Open-Access

yes

Keywords

Female, Humans, Adult, Irritable Bowel Syndrome, Tryptophan, Diet, Microbiota, Gastrointestinal Microbiome, diet, tryptophan, gastrointestinal microbiome

Abstract

BACKGROUND: Imbalance of the tryptophan (TRP) pathway may influence symptoms among patients with irritable bowel syndrome (IBS). This study explored relationships among different components that contribute to TRP metabolism (dietary intake, stool metabolite levels, predicted microbiome metabolic capability) in females with IBS and healthy controls (HCs). Within the IBS group, we also investigated relationships between TRP metabolic determinants, Bifidobacterium abundance, and symptoms of IBS.

METHODS: Participants with IBS (Rome III) and HCs completed a 28-day diary of gastrointestinal symptoms and a 3-day food record for TRP intake. They provided a stool sample for shotgun metagenomics, 16 S rRNA analyses, and quantitative measurement of TRP by mass spectrometry.

RESULTS: Our cohort included 115 females, 69 with IBS and 46 HCs, with a mean age of 28.5 years (SD 7.4). TRP intake (p = 0.71) and stool TRP level (p = 0.27) did not differ between IBS and HC. Bifidobacterium abundance was lower in the IBS group than in HCs (p = 0.004). Predicted TRP metabolism gene content was higher in IBS than HCs (FDR-corrected q = 0.006), whereas predicted biosynthesis gene content was lower (q = 0.045). Within the IBS group, there was no association between symptom severity and TRP intake or stool TRP, but there was a significant interaction between Bifidobacterium abundance and TRP intake (q = 0.029) in predicting stool character.

CONCLUSIONS: Dietary TRP intake, microbiome composition, and differences in TRP metabolism constitute a complex interplay of factors that could modulate IBS symptom severity.