Most coffee drinkers have been in the same tough spot at some point: having to choose between a necessary morning beverage and bowel stability. There’s nothing quite like finishing a coffee and immediately needing to rush to the office bathroom for a poop.

Despite the common experience, it is not entirely understood why coffee sends so many of us directly to the toilet mere minutes after drinking it. Is it because coffee happens to be the first thing we put in our stomachs, or because it is a stimulant? SciShow takes a deeper look in a new video.

Coffee — both regular and decaf — boosts our bodies’ production of the hormone gastrin, which in turn produces more stomach acid and pushes digestion. “There’s something about coffee specifically that leads to the production of this hormone, encouraging your guts to move things along a little faster than normal and interrupting morning meetings everywhere,” video host Michael Aranda says. “We just don’t know what that is.”

Coffee Poop
Coffee makes us poop because of its ability to trigger an unusual reaction in the gut. Photo courtesy of Pixabay, public domain

The stomach acid gastrin promotes is called gastric acid, which when released, breaks down proteins in food and helps the body absorb vitamins, the Hormone Health Network says. It also kills many bacteria that occur naturally in food, helping protect us from infection — which is why people with low levels are at an increased risk of infection in their digestive systems.

Encyclopaedia Britannica adds that gastrin “increases the motility of the stomach, thereby helping to churn food and eventually to empty the stomach; to a lesser degree, gastrin also increases the motility of the upper small intestine and the gallbladder.”

Just as low levels of gastrin can affect health, high levels can be dangerous too, the Hormone Health Network says: On the mild end it can lead to diarrhea, but more severe cases include stomach and small intestinal ulcers.

A damaged stomach lining or certain antacid medications could interfere with gastrin levels, as could a serious condition called Zollinger-Ellison syndrome. The Mayo Clinic explains the rare illness is caused by tumors in the pancreas or small intestine that secrete gastrin, throwing off the balance of stomach acid. People with the condition will have abdominal pain, diarrhea, acid reflux, heartburn, nausea, a decreased appetite and internal bleeding.