People generally associate Gastroesophageal reflux disease (GERD) with excessive production of hydrochloric acid in the stomach. We know that HCL is essential for proper digestion. In acid reflux the acid comes up the esophagus from the stomach due to the insufficiency of esophageal sphincter. But what is the acid that comes up? Is it HCL or lactic acid? Edit: Inappropriate sources removed by moderator And the real cause is under-production of HCL and not the over-production of HCL! Can anyone throw some light on this?