Have you ever ordered an iced mocha with almond milk or an iced vanilla latte with oat milk before class and then later had to poop really badly during lecture? Well, according to science, you aren’t the only one! In fact, about 30% of people need to use the bathroom after drinking coffee.
Contrary to popular belief, caffeine isn’t the main culprit. In 2008, the National Library of Medicine published a study that tested the colonic function (pooping effect) of coffee by comparing caffeinated coffee, decaffeinated coffee, and water. While caffeine did play a role, the researchers found that decaf coffee increased colon activity, though not as much as caffeinated coffee.
Researchers believe that the biggest culprit is coffee’s interaction with stomach acid. Caffeinated and decaffeinated coffee both stimulate a hormone called gastrin. Gastrin signals your stomach to produce more hydrochloric acid and digestive enzymes. This, in turn, promotes digestion and leads us to feeling the need to poop!
Our bodies also experience a gastrocolic reflex when we consume food or drink. This reflex, defined by the stomach “stretching,” makes room for the new food by stretching your stomach and pushing out the old food. The gastrocolic reflex is stimulated by several biological factors and the hormone gastrin is one of them. Studies have also shown that this reflex correlates to our circadian rhythm, so your first coffee may stimulate your stomach even more.
However, you should never rely on coffee to poop, as coffee’s effect on the colon decreases over habitual consumption. Too much coffee can also lead to an upset stomach, diarrhea, insomnia, anxiety, and headaches. So, drink in moderation and find your favorite campus bathroom to poop in safely.
This article was edited by Simon Thill and Sarah McNamara.