Dark-Roasted Coffee Brews Better For Stomach?

By Margarita Nahapetyan

Dark-roasted coffee brews, such as espresso and French roast, appear to be much gentler on the stomach than their lighter counterparts, because these roasts contain a substance that tells the stomach to reduce production of acid, European scientists have discovered.

The experts say that their finding of "culprit" substances could lead to a new generation of tummy-friendly coffee brews with the rich taste and aroma of regular coffee but without the acid-producing chemicals that are associated with stomach irritation. Veronika Somoza, PhD, of the University of Vienna in Austria, and Thomas Hofman, PhD, of the Technische Universitat Munchen in Germany, say that their discovery could help a lot of people who suffer from coffee sensitivity and that, as coffee lovers themselves, they are extremely excited about this study.

To come up with the conclusion, Austrian researchers used cultures of human cells in order to examine the effect of different types of coffee on stomach. They exposed cultures of human cells to a variety of coffee preparations, such as regular roast, dark-roast, mild roast, decaffeinated, and stomach friendly, and looked for the irritants. Instead of just one specific element, the investigators unexpectedly found a mixture of compounds - caffeine, catechols and N-alkanoly-5-hydroxytriptamides - as the chemicals in coffee that contribute to the production of stomach acid.

The scientists say that one of these components, N-methylpyridium, or NMP, which is more common in coffee's dark roasts, such as espresso and French roast blends, seemed to block the ability of stomach cells to produce hydrochloric acid and offered a way to decrease or even prevent stomach irritation. Since NMP chemical is generated only during the process of roasting and is not present in raw coffee beans, darker-roasted coffee brews contain higher amounts of this stomach-friendly substance, the experts say.

How NMP acts on the gastric system at this moment is not well understood. Acid secretion did not change noticeably in stomach cells that were treated with just NMP. And the amounts of caffeine have not been cleared - the tummy-friendly darker brews also contained less amounts of caffeine than their lighter-brewed peers.

Doctors assume that chemicals that are found coffee cause the stomach to overproduce acid, whereas some coffee lovers take antacids or drink decaf coffee in order to decrease this effect. There are also coffee drinkers who switch to a small but growing number of specialty coffee brews marketed as stomach friendly.

The Austrian research team is currently conducting a pilot study in which participants are asked to swallow a sensor embedded in a capsule that measures the stomach's pH and then transmits the readings to a computer. According to the preliminary results, stomach acid surges for a longer time when people drink light-roast coffee compared to dark-roasted brews.

The research was presented on March 21 at the 239th National Meeting of the American Chemical Society in San Francisco.