In a related study, we have found evidence that patients with Barrett's esophagus have a leak for oral sucrose to leave the lumen of their upper gastrointestinal tract, enter the blood, and be filtered into urine. Normally the disaccharide sucrose cannot leave the lumen of the gastrointestinal tract without being first hydrolyzed to glucose and fructose. Appearance of the disaccharide in the bloodstream suggests a paracellular leak of some type in the upper gastrointestinal tract. Once in the blood, sucrose is likewise not taken up or metabolized by the kidney but simply filtered into the urine. The amount of sucrose appearing in an overnight urine sample can be used to indicate the presence of Barrett's esophagus and/or esophagitis in a patient reporting with reflux (GERD) symptoms. The leak is presumably in the Barrett's epithelium itself. This phenomenon will be used to test if a standard 8 week therapy of Nexium in a first-time-presenting GERD patient can reduce the leak as a means of assessing the efficacy of the drug in that patient. We predict that Nexium will reduce leak in esophagitis but not Barrett's patients.