Picture this: It’s Monday morning at the office and you’ve got to start the day off right with a little caffeine, so you pour yourself a nice hot cup of coffee, settle in at your desk, and get to work. But soon your guts start to rumble, things start moving, and you gotta poop.
The phenomenon is so well known that it’s even plastered on mugs. “Coffe makes me poop”.
Around three in ten people find themselves on their way to the bathroom after their morning cup of joe and a small study done in 1990 found that it wasn’t just that people felt the urge to go; within a few minutes of drinking coffee, people who needed to poop also had an increase in motor activity in their colons, so their guts were physically responding to the drink.
Which brings us to the question: “Why?”
Some scientists think that it might be not the coffee at all, it could just be that coffee is the first thing you put in your stomach in the morning and as your stomach stretches, it triggers the gastrocolic reflex. Basically, your guts wake up and start things moving.
On the other hand, drinking a glass of water when you wake up doesn’t necessarily send you to the bathroom, so theres probably more to it than that.
Caffeine could be part of what’s causing the effect. Since caffeine is a stimulant, it could be stimulating some things at the other end, as well. Coffee is pretty acidic and acid in the stomach might be another part of the problem. Where there’s a lot of acid in your stomach, you produce more bile, which can, in turn, cause diarrhea.
But that takes a while and the urge to use the restroom happens just a few minutes after drinking coffee. Research from the 1980s showed that drinking regular coffee and decaf coffee increases the release of a hormone called gastrin, which helps the stomach produce acid and encourages movement in the intestines.
But gastrin wasn’t released when the subjects drank hot water or a stimulated coffee beverage that contained caffenie and sugar.
So there is 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. We just don’t know what that is.