Heartburn is a burning feeling caused by stomach acid regurgitating into the oesophagus from the stomach. One cause of heartburn is a condition called hiatus hernia. With this condition, a small portion of the stomach gets caught in the lower oesophageal sphincter (LES) that separates the oesophagus from the stomach. This same condition can occur if the LES is defective.
In cases of mild to moderate heartburn, actual testing for stomach acid production in one clinic has shown that hypochlorydria occurs in over 90 percent of thousands tested since 1976. In these cases, replacing stomach acid with HCL supplements is almost always successful.