As many as 40 million Americans avoid coffee, or limit their consumption, because it exacerbates stomach upset, "Science Daily" reported in 2010. You may think a switch to decaf will ease your woes, but the caffeine in coffee isn't the only irritant. If you want to soothe your stomach issues, think about changing the type of coffee you drink.
Why Coffee Irritates
Coffee possesses certain chemicals that prompt your stomach to overproduce acid. In 1986, the "Journal of Clinical Gastroenterology" found that caffeinated and decaffeinated coffee had similar stimulating effects on the hormone gastrin, which prompts the release of acid in the stomach. In 2010, European researchers Veronika Somoza and Thomas Hofmann, in a study presented at the 2010 National Meeting of the American Chemical Society, identified caffeine, catechols and N-alkanoly-5-hydroxytryptamides as the compounds responsible for this release. The overproduction of acid exacerbates ulcer symptoms and causes heartburn in prone individuals. Decaf coffee has less caffeine, so it is slightly less likely to stimulate gastrin, but it still contains the other chemicals in varying amounts.
Not all components in coffee are stomach irritants. One compound, N-methylpyridium, or NMP, dissuades your stomach from producing excess acid. This compound only develops during the roasting process. The more a coffee is roasted, the more of this compound it contains. Espresso and other dark roast coffees may therefore be easiest on the stomach. Decaf versions of these dark-roasted coffees exist, but whether or not they are more or less effective on preventing overproduction of stomach acid has not been widely tested.
Coffee not only stimulates mental alertness, it also stimulates your bowels. In some people, this laxative effect leads to stomach cramping, bloating and diarrhea. Caffeine is not the only compound responsible for this effect. When you drink coffee, your body releases a digestive hormone called cholecystokinin, which may be responsible for the abdominal cramping. A 1998 study published in the "European Journal of Gastroenterology and Hepatology" noted that caffeinated coffee's colonic stimulation effects were 23 percent stronger than decaffeinated coffee's effects. Decaf was still almost as strong as a meal in inducing colon activity and had far more effect than drinking a glass of water.
Should You Drink It?
Before the findings of Somoza and Hoffman, little connection between heartburn, gastroesophageal reflux -- also called GERD -- and other stomach problems was scientifically proven. Warnings to avoid coffee when suffering from these conditions was based on anecdotal evidence. Whether or not you continue to consume coffee, regular or decaf, is entirely up to you and your doctor. If you find that coffee makes your symptoms of heartburn worse, try reducing your intake or switching to the darker roasts. If you find that coffee causes loose stools, cut back on your intake -- switching to decaf alone is unlikely to solve this problem.