Fecal Bile Acids, Fecal Short Chain Fatty Acids and the Intestinal Microbiota in Patients With Irritable Bowel Syndrome (IBS) and Control Volunteers: Diet Challenge

What this Trial Is About

Researchers are studying adults aged 18 to 65 years with irritable bowel syndrome (IBS), including those with diarrhea-predominant (IBS-D) and constipation-predominant (IBS-C) types, as well as healthy volunteers without gastrointestinal symptoms. The study aims to understand how changes in the gut microbiome relate to the production of fecal bile acids and short-chain fatty acids (SCFAs) and how these factors may contribute to IBS symptoms. It seeks to identify specific microbiome patterns in IBS subtypes and controls and examine their correlation with fecal SCFAs, bile acids, and bacterial fermentation after a dietary challenge with inulin. Participants will follow a structured schedule including a screening visit, a controlled diet period, and multiple clinic visits. During the study, they will consume a low fiber, high fat diet for four days, and on Day 5 receive a breakfast containing inulin powder to study fermentation. Stool samples will be collected at home and during clinic visits on several days for analysis of microbiota, SCFAs, and bile acids. Optional follow-up includes completing dietary recall questionnaires to assess diet patterns. Throughout the study, participants will complete diaries recording their bowel habits and symptoms, including IBS severity questionnaires for those with IBS. Researchers will collect stool and urine samples, conduct physical exams, and monitor vital signs. Primary outcomes include measurement of fecal bile acids, SCFAs, microbial populations, and fermentation markers over 48 hours. Secondary outcomes focus on stool characteristics over four days. Participant involvement spans from screening through at least Day 7, with optional follow-up between Day 30 and 90.

Irritable Bowel Syndrome and Control Volunteers: Diet Challenge