when you swallow a muscular valve known as the lower esophageal sphincter or les which is located where the esophagus joins the stomach opens to let food into your stomach and then closes to keep your stomach contents from coming back up. the major cause of gerd is that this valve that does not function the way it should -- either because it is weak or because it relaxes inappropriately. a hiatal hernia (in which a portion of the stomach protrudes above the diaphragm into the chest) and poor esophageal muscle contractions also contribute to gerd. diet and lifestyle also play a role. fatty foods mints chocolate alcohol coffee and tea all relax the les. so does nicotine from cigarettes or chewing tobacco. hormonal changes associated with pregnancy can temporarily weaken the les too. obesity can lead to gerd because the pressure of extra weight pushing on your abdomen may "overpower" the les allowing reflux to occur. the same mechanism explains reflux that may occur when you bend over at the waist.
what causes gerd?