But there may be new hope for those suffering chocolate-lovers.

Results from a new study at the University of Michigan Health System, presented today at the Digestive Diseases Week meeting in Atlanta, not only reveal the mechanism by which chocolate irritates the digestive tract of those who suffer with chronic heartburn - also known as gastroesophageal reflux disease, or GERD - but also suggests a novel treatment.

"We demonstrated that chocolate induces GERD symptoms by compromising the ability of the lower esophageal sphincter to prevent the stomach acids from creeping back up the esophagus," says Chung Owyang, chief of the U-M Division of Gastroenterology and professor of internal medicine in the U-M Medical School. "We also found that a medication commonly used for nausea may ease these painful symptoms," adds Owyang, the study's principal investigator.

In the study, seven GERD patients underwent a series of tests. A tube containing a pH monitor was placed in the esophagus to measure acidity. A second tube was inserted into the first part of the small intestine, the duodenum, to deliver chocolate directly to the gut.

After the chocolate infusion, researchers measured the acidity in the esophagus and how long it took the acidity to rebound to normal levels. Researchers also determined the pressure of the lower esophageal sphincter, located at the junction between the stomach and the esophagus.

In a person who does not suffer from GERD, the sphincter acts as a valve and allows substances to go from the esophagus down to the stomach only. In GERD sufferers, the sphincter does not function properly, allowing acid and other substances in the stomach to pass back up to the esophagus.

The researchers found that chocolate significantly increased the number of reflux events and the acid exposure time in the esophagus for the seven patients.

"We found that the chocolate causes a large amount of serotonin to be released from the cells in the intestines," says Wei Ming Sun, Ph.D., research scientist, U-M Department of Internal Medicine. "The serotonin causes the lower esophageal sphincter to relax. The relaxation means the 'door' between the esophagus and stomach is opened and acid is allowed to flow back up to the esophagus."

After documenting the effects, patients were given granisetron - a substance commonly used to counteract nausea. Granisetron was shown in earlier U-M studies to reduce the effects of chocolate on patients who did not have GERD.

"When the patients with GERD took the granisetron, which is a serotonin blocker, there was a significant decrease in the numbers of reflux events, the acid exposure time and the acid clearance time," Owyang says.

Specifically, the chocolate caused an average of 5.4 reflux events in a 30-minute time period. After treatment with granisetron, the events were down to 3.3 in 30 minutes. Acid exposure time decreased by more than a third after granisetron, and acid clearance time decreased from an average of 8.3 minutes just after the chocolate infusion, to 5.9 minutes with granisetron.

This novel approach may provide alternative effective methods for the treatment of GERD without inhibiting normal acid secretion, which is important to digestion and control of bacterial growth.

Next, the researchers plan to conduct a double blind, multi-center trial to confirm this observation.

Other researchers on the project were: Sutep Gonlachanvit, M.D., research fellow, U-M Department of Internal Medicine; Yen H. Chen, M.D., research fellow, U-M Department of Internal Medicine; Han-Chung Lien, M.D., research fellow, U-M Department of Internal Medicine.

Note: If no author is given, the source is cited instead.

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