Acid reflux happens when stomach acid moves up into the esophagus due to a malfunction of the lower esophageal sphincter (LES), a ring of muscle at the entrance to the stomach. Normally, the LES closes tightly after food passes through to prevent acid from escaping, but if it weakens, relaxes at the wrong times, or doesn't close properly, acid from the stomach can flow back up. This backflow causes irritation and a burning sensation in the chest known as heartburn. Several factors can contribute to acid reflux, such as a hiatal hernia (where part of the stomach pushes above the diaphragm), eating large meals or lying down soon after eating, obesity, pregnancy, smoking, certain foods and beverages (like citrus, chocolate, alcohol, coffee), and some medications. Repeated acid reflux can lead to gastroesophageal reflux disease (GERD), a chronic condition where the esophagus is regularly irritated by stomach acid.
In summary, acid reflux happens due to the backflow of stomach acid into the esophagus caused by a weakened or improperly functioning LES muscle, sometimes compounded by other factors that increase abdominal pressure or relax this valve.
