Study of Fecal Bile Acids, Short Chain Fatty Acids, and Gut Microbiota in Adults with Irritable Bowel Syndrome and Healthy Controls Using a Diet Challenge

What this Trial Is About

Researchers are investigating the relationship between fecal bile acids, short-chain fatty acids SCFAs, and the gut microbiota in adults with irritable bowel syndrome IBS and healthy controls. The study aims to identify specific microbiome patterns in IBS subtypes IBS with constipation and IBS with diarrhea and compare these with matched healthy volunteers. It will test if these microbiome signatures relate to fecal SCFAs, bile acids, and bacterial fermentation of an indigestible carbohydrate inulin after a dietary challenge. Participants will undergo a controlled dietary challenge involving a low fiber, high fat diet for several days, followed by a 4-day 100 g fat diet. Stool samples will be collected at multiple time points for analysis of microbiota, SCFAs, and bile acids. The intervention includes ingestion of inulin mixed in water during a clinic visit. Optional dietary follow-up using an online dietary assessment tool is also offered to some participants. Throughout the study, participants will complete bowel symptom diaries, dietary recalls, and IBS severity questionnaires. Stool samples are collected at home and during clinic visits. Physical exams, medical history, and pregnancy tests when applicable are part of screening. Researchers will measure fecal bile acid and SCFA profiles, colonic transit, and stool characteristics. The total participation lasts about a week with additional optional follow-up up to 90 days.

Irritable Bowel Syndrome and Control Volunteers: Diet Challenge