Clinical Research Directory

Inclusion Criteria: * Age 18 years or older * Irritable bowel syndrome by Rome IV criteria with a positive lactulose breath test for small intestinal bacterial overgrowth, defined as a rise of more than 20 parts per million of hydrogen above baseline in the first 90 minutes of testing and/or a methane level of 10 parts per million or greater at any point during the test OR * Irritable bowel syndrome by Rome IV criteria with a lactulose breath test showing a "flat line pattern," with exhaled gas levels remaining very low (3 parts per million or less) with no spikes * Female participants of childbearing age who are sexually active with male partners must agree to use a highly effective method of contraception, such as abstinence, hormonal contraceptive, intrauterine device, or bilateral tubal occlusion Exclusion Criteria: * Negative SIBO breath testing at baseline * Restricted diets (low carbohydrate, Atkins, gluten-free, low FODMAP, or others) * Confirmed celiac disease * Immunocompromised (chronic steroids, biologics), CD4 less than 400, AIDS not on therapy, neutropenia, acute and chronic leukemia, lymphoma * Portal hypertension * Chronic liver disease, defined as: ICD-10 known diagnoses of chronic liver disease; OR known or suspected liver cirrhosis, portal hypertension, or chronic hepatitis; OR serum AST and ALT elevation greater than 2 times the upper limit of normal with decreased serum albumin less than 4.0 g/dL within the last 6 months * Pregnant or breastfeeding * Diagnosis of inflammatory bowel disease * Poorly controlled anxiety or depression despite medication * Untreated significant anxiety or depression * COVID-19 positive * Unable to provide informed consent * Insulin dependent or poorly controlled diabetes mellitus (HbA1c greater than 7.0%) * Connective tissue disease such as lupus or scleroderma * Concurrent narcotic use * Antibiotic or probiotic use within 30 days