A Study to Evaluate the Impact of Lactobacillus Rhamnosus GG on Proton Pump Inhibitor-Induced Gut Dysbiosis

Inclusion Criteria: * Individuals on an unrestricted regular diet with no dietary restrictions (vegan, low FODMAP, gluten free, dairy-free etc) or other fad diets (e.g., keto, intermittent fasting, etc.). * Healthy subjects will be screened for current or chronic GI symptoms using a 16-item questionnaire. * Only those with an absence of symptoms will eligible to participate. Exclusion Criteria: * For healthy volunteers, will include prior surgery altering the esophagus, stomach, and intestine (except appendectomy). * Chronic daily use of medications affecting GI secretion or motor function. * The presence of any GI-motility affecting systemic diseases or untreated psychiatric disease. * Pregnancy.