Here's Why Coffee Makes You Poop

Here's a scenario that is not uncommon, and it might happen to you or someone you know. That first cup of delicious coffee hits your stomach and BAM—you are running to the bathroom like your life depends on it. But are there any scientific reasons behind coffee and when nature calls?

I was going to tell a poop joke, but never mind—it's too crappy. Here's the real reason. 

Why Does Coffee Make You Poop? 

The caffeine in coffee is a proven diuretic, a substance that makes the body excrete more liquid. In other words, you have to pee more. The effect caffeine has on your body is controlled by other factors as well, such as your gender and activity level. A study at the University of Birmingham in the U.K. found that you can actually build up a tolerance to the diuretic effects of coffee.

Well, that takes care of number one, but what about number two?

Caffeine can, in fact, be a laxative to some people as well. The chemical affects your large intestine and causes it to contract in much the same way that it does after you eat a large meal. But this is only felt in about 30% of the population. So what is the real culprit here?

Coffee Can Cause Colon Contractions

The colon experiences three types of contractions that work together to brew up and ultimately eject poop. These contractions are influenced by muscular, neural and chemical factors, and the occurrence, timing and frequency can vary from person-to-person. Coffee can stimulate this colonic activity within just minutes of consuming it.

Studies have shown that drinking coffee is more effective than water at inducing bowel movements—that’s saying something since “water is an integral part of normal digestion with large amounts being released and reabsorbed by your digestive tract every day,” said Staller, an assistant professor of medicine at Harvard Medical School. Caffeinated coffee is 60% more effective than water at stimulating colonic motor activity and 23% more impactful than decaf.

According to another study, participants also said coffee gave them the urge to poop. Their colon activity increased within four minutes of drinking unsweetened black coffee, an effect that lasted at least 30 minutes.

Science doesn’t lie—when that coffee hits your stomach, the stomach lining triggers either a nervous system or hormonal response that causes the colon to start contracting and moving the stool in the colon toward the rectum—and that’s why you’re running to the bathroom after just a few sips of coffee.

Coffee Can Stimulate Hormones and Stomach Acid

Coffee appears to also stimulate the release of the hormone gastrin, which produces stomach acid (gastric acid). Stomach acid aids in food digestion and also promotes colonic activity—which may be why coffee can have an effect similar to a laxative on some people. The chemical affects your large intestine and causes it to contract in much the same way that it does after you eat a large meal.

According to some scientists, the caffeine amount in a normal cup of coffee and the amount of caffeine that is consumed daily are factors to a person's poop schedule. A normal 12-ounce cup of coffee contains 100-150 milligrams of caffeine, which is higher than a glass of Coca-Cola, for example, topping out around 34 milligrams. Death Wish Coffee contains an extra kick of caffeine—hence, why we’ve probably found the cure for your constipation woes. 

The acidic nature of coffee can also lead to higher production of bile acids in the body. Also, what you add to your cup of joe might contribute to another trip to the toilet. Artificial sweeteners and dairy products both lead to gastrointestinal issues like gas and bloating. 

So, should you depend on your morning cup of coffee to stay regular? If you’re constipated, drinking coffee to help move things along isn’t unreasonable. Coffee is rich in antioxidants, digestive benefits and provides the cognitive energy boost you need to get things moving. As to whether you poop or not after your first sip—well, that’s none of our business.

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