Now, enjoy coffee without getting heartburn

Research has led to the counter-intuitive finding that espresso, French roast and other dark-roasted coffee may be easier on the tummy because these roasts contain a substance that tells the stomach to reduce production of acid.

The research could lead to a new generation of stomach-friendly brews with the rich taste and aroma of regular coffee, the scientists said.

"This discovery is going to help a lot of people who suffer from coffee sensitivity," says Veronika Somoza, from the University of Vienna in Austria, and Thomas Hofmann from the Technische Universität München in Germany, who conducted the study.

Estimates suggest that up to 40 million people in the US alone either avoid coffee, or cannot drink as much as they like, due to stomach irritation. Doctors think that chemicals in coffee cause the stomach to overproduce acid.

The processes used to produce stomach-friendly coffee also can reduce the amount of healthful substances in the brew, including some that scientists have linked to benefits such as protection against diabetes and heart disease, Somoza said. In addition, the processing can affect the robust taste and smell of coffee.

To study the irritants in coffee, the scientists exposed cultures of human stomach cells to a variety of different coffee preparations, including regular, dark-roast, mild, decaffeinated, and stomach-friendly. They identified several substances that appeared to trigger chemical changes associated with increased acid production. These substances include caffeine, catechols, and other ingredients.
"We found out there's no single key irritant. It is a mixture of compounds that seem to cause the irritant effect of coffee," Somoza said.

The findings were presented at the 239th National Meeting of the American Chemical Society in San Francisco.