Why are so many people having heartburn?
Heartburn is actually caused by the stomach working too hard and sloshing acid up into the throat.
Eating a very large meal can over fill the stomach and cause pressure on the bottom of the throat, allowing acid to escape the stomach.
Other foods can cause the esophageal muscle (between the stomach and esophagus) to relax and allow stomach acid to escape.
Stress can also cause the stomach to over produce acids.