Dietary Fiber for Irritable Bowel Syndrome

The goal of this clinical trial is to characterize regional intestinal fermentation physiology and determine how the response to fermentable dietary fiber differs between healthy individuals and individuals with irritable bowel syndrome (IBS). The study will use ingestible capsule technologies to directly measure intestinal gases and regional microbiome composition following low-fiber and high-fiber meal challenges.

The main questions it aims to answer are:

Does the change in regional intestinal gas levels following a fermentable-fiber challenge differ between participants with IBS and healthy controls? How are regional intestinal gas dynamics associated with microbiome composition, breath gases, serum short-chain fatty acids, glucose dynamics, metabolites, and gastrointestinal symptoms?

Researchers will compare participants with IBS to healthy controls to determine whether intestinal fermentation responses to dietary fiber differ between these populations.

Participants will:

Complete two study visits approximately one week apart. At one visit, participants will receive a low-fiber control meal, and at the other visit, they will receive the same base meal containing 15 g of inulin. The order of the two meals will be assigned at random.

Swallow an Atmo gas-sensing capsule to measure intestinal H2, CO2, and O2 and a CapScan capsule to collect regional intestinal fluid for microbiome analysis.

Undergo serial blood and breath sampling and gastrointestinal symptom assessments during each 8-hour study visit.

Complete stool and urine collections, dietary assessment, and continuous glucose monitoring before and/or after the study visits.