Effect of Omeprazole on Gut Microbiota in Adults With Obesity and GERD

This randomized, open-label, parallel-group study will evaluate the effect of short-term omeprazole therapy on gut and oral microbiota in adults aged 50-65 years with obesity and symptomatic gastroesophageal reflux disease. Participants will be randomized 1:1 to receive omeprazole 20 mg once daily for 14 days plus standard non-pharmacological recommendations for gastroesophageal reflux disease, or standard non-pharmacological recommendations alone. Clinical and laboratory assessments will be performed at baseline and after 14 days. Stool and saliva samples will be collected to assess gut and oral microbiota, and blood samples will be collected for laboratory biomarkers.