Of all the digestive conditions, heartburn is definitely one of the most firey. It's caused by stomach acid back-flowing into the esophagus, called gastroesophageal reflux or GERD. A little bit of reflux is normal at most meals, but a lot of reflux and at increased frequency can lead to discomfort and tissue damage. A common thought is that heartburn is caused by too much stomach acid. Brace Yourself... Usually it's the opposite ! Not having enough stomach acid can make the