Coffee poops, but not because of caffeine

© Oscar Wong / Getty Images
Coffee has a natural laxative effect, but doctors don’t know exactly why. Oscar Wong / Getty Images

• Coffee promotes bowel movements, although doctors are not sure exactly why this happens.
• Caffeine is not the reason why coffee makes some people poop, since decaffeinated coffee can have the same effect.
• Four cups of coffee is the maximum recommended amount you should drink each day.
• Visit the Insider Health Reference Library for more advice.

For many people, a day does not start unless they have had a cup of coffee, but this staple in the morning is often followed by a trip to the bathroom. In a small 1990 study, coffee stimulated evacuation in 29% of participants. However, there is no definitive answer as to what is in the coffee that causes a laxative effect.

Most people think caffeine is to blame. Although caffeine has been shown to cause an early need to defecate and is a known stimulant, decaffeinated coffee can also stimulate bowel movements.

“It must be something about coffee as a whole, rather than caffeine alone, that encourages evacuation,” says Jill Deutsch, MD, director of the Yale Functional Gastrointestinal Disorders Program.

Here’s what you need to know about the laxative effects of drinking coffee.

Why does coffee poop you?

The exact reason for the laxative effect of coffee is not clear, but doctors assume it is a combination of factors. “The short answer is that we are not sure! It seems that just the general formulation of coffee helps us poop,” says Deutsch.

How coffee affects your intestines:

• Milk: Drinking milk can cause bloating, increased gas and diarrhea in people with lactose intolerance, the inability to digest the sugar found in dairy products. They can benefit from choosing lactose-free milk options, such as soy milk, oats, coconut and almonds.
• Gastrin levels: Both caffeinated and decaffeinated coffee can increase levels of gastrin, the hormone that makes the colon more active.
• Colon motor function: With or without caffeine, coffee can stimulate the motor activity of the colon or the contractions that cause the urge to evacuate.
• Time: Colon motor activity naturally increases after waking up, which may explain why some people feel like going to the bathroom in the morning.

There is no specific amount of coffee that encourages evacuation because it is different for each person. “Not everyone gets the same type of laxative benefit from drinking coffee. And, in fact, some people are not affected by drinking coffee, ”says Deutsch.

Is it healthy to drink coffee as a laxative?

If it works for you, it may be healthy to drink coffee as a laxative, says Deutsch. Consuming up to 400 milligrams of caffeine per day is safe and without adverse effects, which is approximately the amount in four cups of coffee. However, sustained consumption of higher doses can lead to caffeine addiction.

What the research says: According to a 2013 study, caffeine is the most widely used drug in the world. It is important to consume less than 400 milligrams of caffeine a day to avoid symptoms of caffeine addiction, such as a strong desire to continue using the drug, difficulties in controlling the drug consumption and withdrawal.

Other drinks also contain caffeine, such as soft drinks, teas (including kombucha) and energy drinks. However, there is no research proving that they provide a laxative effect similar to that of coffee. “We have no data to support that other caffeinated beverages encourage evacuation,” says Deutsch.

Insider Takeaway

Caffeinated and decaffeinated coffee stimulates bowel movement in some people, but there is no solid reason for this. The general digestive effects of coffee, milk and the time you drink can contribute to the laxative effect.

It may be healthy to drink coffee as a laxative if it works for you, but prolonged consumption of more than 400 milligrams of caffeine per day (which means about cups of coffee) can lead to caffeine addiction. Remember that caffeine is not only found in coffee, but also in teas, soft drinks and energy drinks, although it is not proven to stimulate bowel movement.

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