Stanford University
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.
Irritable Bowel Syndrome (IBS) affects an estimated 25-45 million people in the United States, accounts for roughly 20-40% of gastroenterology visits, and imposes a major societal burden, with annual U.S. costs estimated at approximately $1.7-$10 billion in direct medical spending and approximately $20 billion in indirect costs from lost productivity (Hulisz 2004; Leong et al. 2003; Canavan et al. 2014). Despite this burden, IBS remains poorly understood, and no validated biochemical diagnostic or curative therapy currently exists (Lacy et al. 2021; Kim et al. 2017). In most individuals, a hi…
Inclusion Criteria: 1. Age 18-75 years. 2. Able to provide written informed consent. 3. Able and willing to swallow capsules and complete all study procedures. 4. For the Healthy cohort: no history of a diagnosed chronic GI disorder and no ongoing GI symptoms warranting clinical evaluation. 5. For the IBS cohort: meets Rome IV diagnostic criteria for IBS, with a prior clinical hydrogen/methane breath test on record sufficient to assign a breath-test subtype. 6. Willing and able to complete a virtual (Zoom) screening visit and two in-clinic study visits approximately one week apart. Exclusion…
Participants consume a standardized breakfast shake containing 15 g of inulin at one of the two study visits, according to the randomized meal sequence. At the other visit, they consume the same base shake without added inulin as the low-fiber control. Visits occur approximately one week apart.
Participants consume the standardized low-fiber base breakfast shake without added inulin at one of the two study visits, according to the randomized meal sequence. This condition serves as the within-participant control. Visits occur approximately one week apart.
At each of the two study visits, participants will swallow one Atmo gas-sensing capsule with the assigned standardized breakfast shake at t=0. As it transits the gastrointestinal tract, the wireless capsule records regional luminal hydrogen (H2), carbon dioxide (CO2), oxygen-related signals, temperature, and transit-related data. Data are transmitted by radiofrequency to a wearable receiver for analysis. Capsule passage will be monitored after each visit.
At each of the two study visits, participants will swallow one CapScan capsule at t=4 hours. CapScan is a single-use, passive ingestible device that collects regional gastrointestinal luminal fluid as it transits the intestine. The collected samples will be used for ex vivo microbiome and multiomic analyses. The device passes in the stool and is retrieved by the participant using the provided retrieval materials for subsequent processing.