Why Does Coffee Upset the Stomach?

The answer isn’t just in caffeine: coffee contains a wide variety of compounds, including chlorogenic acids and trigonelline. These can stimulate stomach acid production and potentially trigger gastric pain in some people. But it’s also worth mentioning that the acid itself is not likely to make a difference for most people, unless you have a true acid sensitivity.

In addition to the acids, coffee can contain more than 800 volatile compounds, all of which affect everyone differently. Caffeine is the most prevalent, and it’s technically a psychoactive substance, meaning that it can cause GI distress in some people.

If you’re a heavy drinker and are constantly experiencing stomach discomfort, it may be time to try cutting back on coffee. But before you do, it’s important to figure out what exactly is causing your gastrointestinal issues.

The most common reason that coffee upsets the stomach is because it’s not consumed on a full stomach. When you have a full belly, your stomach has a natural buffer against the acid that coffee can trigger. But if you drink your coffee on an empty stomach, it will hit the system with two punches: The acid and the caffeine.

This can lead to a lot of stomach discomfort, and it can even lead to ulcers in the long term. Another common factor that causes coffee to upset the stomach is because it can promote acid reflux, which can be painful for some people. This is because the caffeine can relax the lower esophageal sphincter, which then allows stomach contents, acid and all, to float up into the esophagus.