Why Does Coffee Make You Poop?

Everything you want to know—but are too shy to ask—about one not-so-subtle side effect of coffee.

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For many of us out there, our morning cup of coffee is more than a bare necessity; it’s a beloved ritual. Unfortunately, the way that ritual ends is kind of crappy. Literally. Like that time I grabbed my to-go cup only to find myself stuck on the slow-moving subway for half an hour, clenching in quiet desperation, yearning for a restroom. True story.

According to the National Coffee Association, 62 percent of Americans drink coffee on a daily basis and the average amount per day is 3.1 cups per person. According to one study, 29 percent of participants reported having to poop within 20 minutes of consuming a cup of coffee.

Does any of this sound painfully familiar? Rest assured, you are not alone. If you’ve always wondered why coffee makes you poop, but have been too shy to ask, we’ve got you covered right here.

Coffee Makes You Poop: Fact or Fiction?

Fact. Coffee makes you poop. There, we said it. And while many of us can’t start our day until we’ve had a piping hot cup, we do so through gritted teeth and cross our fingers no one is in the company bathroom 10 minutes later.

“It’s clear coffee makes you poop,” say Will Bulsiewicz, MD, a practicing gastroenterologist with 16 years of training. He is also a speaker, blogger, and microbiome specialist. “I can speak not only for my patients but also for myself that there is no question about it. The real question is why? The answer, however, is not completely clear at this point.”

A study done by one of the top gastroenterology and hepatology journals in the world, Gut, concluded that there was a clear stimulation of the colon after the participants in the study drank coffee. However, the stimulation occurred only four minutes after consuming the coffee. “This means that it’s not a direct effect of the coffee stimulating the colon,” says Bulsiewicz. “It is impossible for coffee to reach the rectum in four minutes. It typically takes hours. This suggests there’s a stimulation when the coffee hits the stomach.”

This is known as the gastrocolic reflex, which is a signal that the stomach sends to the colon when food is coming down the pipe, causing it to start to stimulate bowel movements. “When it comes to coffee stimulating bowel movements, based on this study, it’s quite clear that coffee has a similar effect,” adds Bulsiewicz.

A logical guess would be that caffeine is the trigger that sends this message. Coffee is one of the most concentrated sources of caffeine, which is a natural stimulant. One study shows that consuming caffeine results in contractions in the colon and intestine, which can result in the need to poop and another study shows that caffeinated coffee stimulated colon activity 23 percent more than decaf coffee, and 60 percent more than plain water.  

So decaf makes you poop, too…

The same study has concluded that decaf coffee produces a similar effect on colon stimulation and bowel movements as caffeinated coffee does. This means that there’s something other than caffeine at play. One theory points to chlorogenic acid, which is one of the components of both caffeinated and decaf coffee that is super healthy. “This unique compound found in coffee is what stimulates the stomach to have a visceral response or gastrocolic reflex,” says Bulsiewicz.

How we take our coffee could be a deciding factor as well. “It’s not disputable that lactose is something that can promote bowel movements, particularly in people who are lactose sensitive or intolerant. If you add dairy to your coffee, of course it will stimulate bowel movements,” says Bulsiewicz.

He also warns against artificial sweeteners, which can be just as unhealthy as processed sugar and can cause diarrhea. Bulsiewicz says the healthiest way to consume your coffee is black. But if sweet is your thing, give consideration to inulin, which is derived from plants, completely natural, good for the gut, and tastes sweet.

Does one size fit all?

With so many factors at play, and given that no two bodies are alike, how much validity can we give to the statement If I drink coffee, then I will poop?

That all depends. According to the previously mentioned study, only 29 percent of participants felt the urge to poop after drinking coffee. “We all have a gastrocolic reflex to some degree, but I’ve come across and taken care of people who have one out of proportion to other people,” says Bulsiewicz. “There are some people [who are] going to be more sensitive and can clearly have a more pronounced response.”

The timing of when we drink coffee may also play a role in when we have to poop. Waking up in the morning is dependent on our natural biological rhythm, known as the circadian rhythm. That stimulation also wakes up our intestines and stimulates the bowels to move. “It’s very normal for people to have a bowel movement in the morning without coffee,” says Bulsiewicz.

The Bottom Line on Bowel Movements

We can all agree that coffee can make you poop, but the line between point A and point B isn’t as straight as we originally thought. It turns out  there are a few factors involved. And while we love our cups of coffee, we might not love the immediate, sometimes uncomfortable, reaction.

The best way to reduce any unpleasant effects of coffee on the bowels is to make sure that your body is getting enough dietary fiber, which is found in fruits and veggies, and helps to keep our bowel movements regular and healthy. Routine consumption of fiber increases regularity. Drinking water over coffee is another way to stay regular without that impulsive, gurgling feeling we are all too familiar with.

That said, coffee is and can be a very healthy part of anyone’s morning routine. “Coffee protects the liver, protects against Alzheimer’s and dementia, and in many of these studies, it seems to be a dose response where more coffee is better,” says Bulsiewicz.

Keep in mind that too much caffeine can have negative effects on the body as well, as it’s associated with insomnia and digestive issues. Bulsiewicz’s take? “Coffee can be a healthy part of a morning routine, but I would say what is far more important is that we drink water.”

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