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Here's how coffee can make you poo

by Tina Sendin 6 min read

Here's how coffee can make you poo

We all love our cup of joe. Whether it’s because of the surprising health benefits it brings, the occasional buzz we need, or just a habit we’ve formed, it’s become an indispensable part of our everyday life.

But did you know that “nature’s call” comes with your java fix?

This is NOT a drill.

According to various studies, coffee can make you poop.

If you think this is a whole load of crap (pun intended), then keep reading to find out what researchers have found about coffee, caffeine and your daily toilet run.



A 1990 study showed that 29 per cent of participants had to go for a “number 2” within twenty minutes of drinking a cup of coffee. [1]

This shows coffee having a laxative effect on our body.

Here are 7 reasons why coffee makes you go:


#1 Coffee, as a rich source of caffeine, can stimulate your colon and gastrointestinal muscles that make them get rid of food from the body faster.

In the same 1990 study mentioned above, coffee prompts a “gastrocolonic response” within just a few minutes of downing a cup of joe. [1] The study didn’t specify the reasons back then, but more recent studies explain why.

Several have found that coffee can induce contractions in the colon and intestinal muscles, causing them to push food more quickly towards the rectum. This is the final section of the body’s digestive process. [2, 3]

The Washington Post published an article titled “Here’s Why Coffee Makes You Poop” that reflects what the other studies have shown: [4]

Scientists have observed—by way of some very invasive studies—that coffee of any sort can stimulate the distal colon, which helps push waste out of the body more quickly. So the physical mechanism is well understood, but not what triggers it.



Also, caffeine causes the colon to become 60 per cent more active than just water alone, and 23 per cent more active than a decaf. [5] But this isn’t to say that decaf doesn’t have any laxative effect, because it does! [6, 7]

The 1990 study also shows that caffeine may not have anything to do with more activity in the gut.

It found that even decaffeinated coffee causes more contractions in the colon and gastrointestinal muscles, prompting one to defecate. [1]

In fact, other studies show that several factors – other than presence of caffeine in a drink – may have a role to play. [8]


#2 Coffee has acids that stimulate hormones concerned with “number 2.”

Coffee’s acidic nature may be a reason for an easier poo. It stimulates bile production and this fluid, when released by the gall bladder into the intestines, can cause diarrhea. [9]

The Washington Post reflects this finding as well: [4]

It’s possible that the acidity of coffee is the key: Coffee has a compound called chlorogenic acid that triggers higher stomach acid levels and also higher production of gastric acid. It could be that the overall acidity bump makes the stomach dump its contents out more quickly than usual. Something in coffee may also trigger the release of hormones that aid digestion, which would speed up bowel movements. But it’s not clear which of the hundreds of chemicals found in a cup of coffee are responsible for that boost.

Essentially, various studies show that coffee stimulates the production of stomach acid that pushes food faster through the gut and into the rectum. [10, 11]



#3 Coffee may kill off gut bacteria, making it easier to poo 

So what is it about coffee that impacts your bowel movements?

Perhaps one of the most recent studies on the matter shows that coffee may eliminate gut bacteria, which has an effect on how fast and easy it gets when pooping.

A preliminary study done on rats have found that subjects that consumed both caffeinated and decaffeinated coffee had less bacteria in their poop, compared to those that didn’t drink coffee.



According to an article published by Gizmodo: [12]

Researchers at the University of Texas Medical Branch at Galveston fed their rats a tiny cup of joe for three days straight, with different groups getting both caffeinated and decaf coffee. Then, the researchers checked the downstairs plumbing of the rats with a physical examination and probe, focusing on the muscles that contract and help guide food (and eventually waste) through the gut. Lastly, they also studied how muscle tissues from the gut directly reacted to coffee in the lab. Their results were clear: muscles in the small and large intestine were more able to contract post-coffee, meaning things could move faster along the gut.

While it doesn’t involve humans (and thus more research is needed to arrive at a strong conclusion), this recent study reflects those same findings done way back in 1990 saying that coffee’s impact on gut motility has nothing to do with caffeine.


#4 Coffee can stimulate hormones

The Gut study conducted in 1990 also showed that coffee induces the release of the hormone gastrin in the stomach, known for stimulating more colon activity. [13]

The release happens in the area closer to the rectum, which leads researchers to believe that this increased activity can actually bring about laxative effects.

It doesn’t matter whether you drink regular or decaf – coffee has been found to naturally increase gastrin levels by 2.3 and 1.7 times, respectively, in comparison to water. [14]

Apart from gastrin, coffee also increases the levels of cholecystokinin, a digestive hormone that not only stimulates food movement through the gut, but also leads to a more active colon due to gastrocolic reflex. [15, 16] This is the same reflex that happens after eating a meal.


#5 Those add-ons on your cup of joe influence your bowel movement too

Did you know that more than two-thirds of American coffee lovers add milk, cream, sugar, sweeteners and other additives onto their java? [17]

These additives contain lactose, which can make you poo more. Unfortunately, 65 per cent of people in the world are lactose-intolerant. [18, 19] And these add-ons have something to do with your gut activity!



#6 The amount of caffeine in your drink has something to do with it too

Most people think it may be the caffeine that stimulates the bowels, but people don’t get the same laxative effect from caffeinated soda that they get from coffee. And they do get a laxative effect from tea, though not as strong as with coffee.

The main reason for this? The sheer amount of caffeine found in a beverage.

This Huffington post explains that the amount of caffeine in a drink may have something to do with how easy it is to go: [20]

We know that caffeine is the culprit because regular coffee is a lot better at this laxative effect than decaf, according to William DePaolo, a molecular microbiology and immunology professor at the Keck School of Medicine at USC. There can be anywhere from 80 to 135 milligrams of caffeine in one eight-ounce cup of brewed coffee, and up to 175 milligrams in drip coffee. [21] In contrast, Coca-Cola has only 34 milligrams of caffeine, which explains why soda doesn’t have the same laxative reputation as coffee.

According to the International Foundation for Functional Gastrointestinal Disorders, going beyond three cups of coffee may cause diarrhea for some people. [22]



While coffee may be the main reason for a regular trip to the loo, other factors may also be at play.

According to an article published in Men’s Health in May 2019, the time you drink coffee may also affect your bowel movement: [23]

Your colon is about twice as active in the morning thanks to your body’s circadian rhythms, says Dr. Rao. Add in breakfast, wash it down with coffee—both of which independently spark colonic contractions—and you can see why you’re clamoring for a crap afterward.



To avoid spending too much time in the restroom, try to time your first cup of coffee 2 hours after getting out of bed. This will give enough leeway for your colon and gut to wake up and pace itself from its morning motor activity.

And when you finally get a hold of your cup of joe, try to veer away from add-ons, pairing coffee with too much food, or doing your caffeine fix around the time of your morning workout. These things can increase your gut activity too.

Try to ease off on your coffee intake – maybe have one in the morning and one in the afternoon. (Here’s when the best time to drink your coffee is.)

And of course, you can always pop a caffeine mint to get that buzz without the unnecessary trip to the toilet!



[1] https://www.ncbi.nlm.nih.gov/pubmed/2338272

[2] https://www.ncbi.nlm.nih.gov/pubmed/18350336

[3] https://www.ncbi.nlm.nih.gov/pubmed/26222930

[4] https://www.washingtonpost.com/news/speaking-of-science/wp/2015/08/10/why-does-coffee-make-you-poop/

[5] https://www.ncbi.nlm.nih.gov/pubmed/9581985

[6] https://www.ncbi.nlm.nih.gov/pubmed/2338272

[7] https://www.ncbi.nlm.nih.gov/pubmed/9581985

[8] https://www.ncbi.nlm.nih.gov/pubmed/9581985

[9] http://www.theibsnetwork.org/wp-content/themes/maintheme/pdf/bile.pdf

[10] https://www.ncbi.nlm.nih.gov/pubmed/24510512

[11] https://www.ncbi.nlm.nih.gov/pubmed/19621729

[12] https://gizmodo.com/why-does-coffee-make-us-poop-scientists-gave-coffee-to-1834852779

[13] https://www.ncbi.nlm.nih.gov/pubmed/2338272

[14] https://www.ncbi.nlm.nih.gov/pubmed/3745848

[15] https://www.ncbi.nlm.nih.gov/pubmed/10499460

[16] https://www.ncbi.nlm.nih.gov/pubmed/8938905

[17] https://www.sciencedirect.com/science/article/pii/S003335061630453X

[18] https://ghr.nlm.nih.gov/condition/lactose-intolerance

[19] http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2036.2001.00952.x/full

[20] https://www.huffpost.com/entry/coffee-laxative-effect-makes-you-poop_n_7546170

[21] http://www.math.utah.edu/~yplee/fun/caffeine.html

[22] http://www.iffgd.org/site/gi-disorders/functional-gi-disorders/diarrhea/common-causes/

[23] https://www.menshealth.com/health/a19547837/why-coffee-makes-you-poop/

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