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Brewing a Gentler Java

Scientists Discover Substances in Coffee That Cause Stomach Irritation
WebMD Health News
Reviewed by Laura J. Martin, MD

March 22, 2010 - Scientists in Europe say they’ve pinpointed several components of coffee that may cause many people to suffer stomachaches and heartburn.

The researchers say their discovery of "culprit" substances could lead to a new generation of stomach-friendly brews with the rich taste and aroma of regular coffee but without the acid-producing chemicals that cause irritation.

Veronika Somoza, PhD, of the University of Vienna in Austria, and Thomas Hofman, PhD, of the Technische Universitat Munchen in Germany, say their finding "is going to help a lot of people who suffer from coffee sensitivity" and that, as coffee lovers, they’re "very excited about this research."

They say their research shows, for the first time, that caffeine, catechols, and chemical-substances called N-alkanoly-5-hydroxtryptamides stimulate molecular mechanisms of stomach acid secretion in human stomach cells.

"We found out there’s no single, key irritant," Somoza says in a news release. "It is a mixture of compounds that seem to cause the irritant effect of coffee."

That effect is apparently significant, explaining why up to 40 million people in the U.S. alone either shun coffee or know they can't drink as much as they’d like.

"The problem is that studies have not verified the stomach irritating potential of coffee or its components until now,” Somoza says. "Manufacturers currently make ‘stomach friendly’ coffees by processing raw coffee beans with steam or solvents intended to reduce levels of the irritants."

But the processes used to make such stomach-friendly concoctions can also reduce the amounts of healthful substances, Somoza says, including some that have been linked to benefits, such as protection against diabetes and heart disease.

Ironically, the researchers report, espresso, French roast, and other dark-roasted coffee may be less hard on the stomach because they contain a substance that tells the stomach to reduce acid production.

Stomach-Friendly Coffee

The scientists exposed cultures of human cells to a variety of coffee preparations, including regular, dark-roast, mild, decaffeinated, and stomach friendly, and pinpointed the irritants.

They say they unexpectedly found that one of the components, N-methylpyridium, or NMP, seemed to block the ability of stomach cells to produce hydrochloric acid and could offer a way to reduce or avoid stomach irritation.

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