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
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
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
"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.
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
Since that chemical is generated only during roasting and isn’t found in raw
coffee beans, darker-roasted coffees contain higher amounts of this
stomach-friendly substance, the researchers say.
According to Somoza, dark-roasted coffee can potentially contain up to twice
as much of this beneficial ingredient as light-roasted brews, but its levels
vary widely depending on the variety of bean and the roasting method.
"Since NMP is generated upon roasting, dark-roasted coffees contain high
amounts of this stomach friendly coffee ingredient," the researchers say.
"There is hope for a good morning start with a freshly-brewed cup of
optimized stomach friendly coffee,” they say.
They are testing varieties of raw coffee beans and different roasting
methods to try to boost levels of the "stomach friendly" chemical.
Their research was presented in San Francisco at the annual meeting of the
American Chemical Society.