Clinical Research Directory

Inclusion Criteria: * Age 50 to 65 years, inclusive. * Obesity, defined as body mass index (BMI) ≥30 kg/m². * Symptomatic gastroesophageal reflux disease with mild or moderate typical symptoms, including heartburn and/or regurgitation. * For female participants, postmenopausal status, defined as absence of menstruation for at least 12 months without another apparent cause of amenorrhea. * Written informed consent to participate in the study. Exclusion Criteria: * Severe or exacerbated GERD, or GERD requiring acid-suppressive therapy or additional diagnostic evaluation. * Use of proton pump inhibitors or histamine H2-receptor antagonists within 8 weeks prior to enrollment. * Use of systemic antibiotics within 3 months prior to enrollment. * Use of probiotic or synbiotic supplements within 8 weeks prior to enrollment. * Inflammatory bowel disease, celiac disease, or other severe chronic gastrointestinal disorders that may substantially affect the gut microbiota. * History of bariatric surgery or other major gastrointestinal surgery. * Acute infectious or inflammatory disease at enrollment. * History of myocardial infarction or stroke. * Type 2 diabetes mellitus. * Chronic heart failure, New York Heart Association functional class III-IV. * Chronic kidney disease with estimated glomerular filtration rate \<30 mL/min/1.73 m². * Alcohol dependence or other substance use disorder. * Severe psychiatric disorder or cognitive impairment that may interfere with providing informed consent or adherence to the study protocol. * Known hypersensitivity or contraindications to omeprazole.