A Study of Glutamine to Treat Intestinal Permeability in Functional Dyspepsia

Inclusion Criteria: * Meet Rome IV criteria for functional dyspepsia (https://theromefoundation.org/rome-iv/rome-iv-criteria/) * Patients will generally be in good health. During initial evaluation, patients' symptoms will be assessed and patients categorized into either the PDS, EPS or mixed subtype of FD. Exclusion Criteria: * Significant comorbid illness * Symptoms are thought to represent an organic disorder (e.g., peptic ulcer disease, hepatitis, pancreatitis, inflammatory bowel disease, type I diabetes, a known malignancy, radiation-induced injury, an active infection, vasculitis, celiac disease), or if the patients have known esophagitis, eosinophilic esophagitis or H. pylori. * Prior surgery to the esophagus, stomach or duodenum will be excluded, as will those taking proton pump inhibitors (PPIs), opioids, corticosteroids and those taking regular (daily) antihistamines, non-steroidal anti-inflammatory drugs (NSAIDs), or mast-cell stabilizing agents within the prior 2 weeks. Of note, patients taking PPIs will be given the opportunity to discontinue their PPI in favor of famotidine 20 mg daily for 2 weeks before enrollment. * Known allergies to lactulose: mannitol. * Active tobacco use and excessive alcohol use (defined as 8 or more drinks per week for women or 15 or more drinks per week for men; http://ww.cdc.gov) * Co-existing IBS will be allowed to enter the study as long as symptoms are not predominant. * Hepatic and renal impairment within the past 6 months. Defined as AST/ALT \> 2X ULN, Total Bilirubin \> 2 X ULN, Estimated Glomerular Filtration Rate (eGFR) of \< 60 mL/min/BSA. * Diagnosed with galactosemia. * Pregnant or breastfeeding women. * Patients with documented or reported lactose intolerance.