Of the variety of effects coffee produces, it makes a significant percentage of people feel the urge to poop. This may or may not be a welcome reaction. Although the coffee bean is actually the seed of the coffee fruit, it has effects that you might attribute to other beans.
Coffee can create an urgent need to run to the bathroom for some people. For others, it brings on a bowel movement in a more subtle way. It depends on your individual body chemistry, but there are some general guidelines for figuring out the odds of whether or not your number one drink will move your body to a quick number two.
Who Feels the Laxative Effects of Coffee?
According to a classic study on the topic, coffee makes about 29 percent of the population need to poop soon after drinking. Far more women than men reported the effect, with 53 percent of the women in the study and 19 percent of the men. However, this was a small study.
When Do You Need to Poop?
In the study, 52 percent said that coffee only made them have a bowel movement in the morning. Similarly, 58 percent said that coffee only had this effect if they hadn't defecated yet that day. Those who were "moved" by coffee said that there was a span of about 20 minutes between drinking coffee and visiting the toilet. In a 2005 study, measurements indicated that coffee triggered a reaction in the colon within 30 minutes of coffee intake.
Why Does Coffee Make You Poop?
The main documented reason for coffee making people defecate has to do with a reaction in the distal colon, which is located at the end of the colon. The reasons for this are not well understood but scientists speculate that it is due to the hormonal effects of the exorphins in coffee (which bind to opiate receptors that slow down or speed up your gut) and two naturally occurring chemicals in coffee called gastrin and cholecystokinin. These chemicals are absorbed into the blood and directed to the brain and colon. They may stimulate muscle contractions in the lower colon, thus promoting bowel movements in the 20 minutes after coffee is consumed.
Additionally, coffee is high in magnesium, which can also make people poop. Some say that the caffeine causes this, but decaf coffee has been shown to be just as likely to make people have a bowel movement as regular coffee.
But other factors may be at play. Artificial sweetener, cream, or milk in your coffee can trigger defecation in those who are sensitive to them. Some people have lactose intolerance with symptoms that can include loose stools when they consume dairy products. Alcohol sugars such as mannitol, sorbitol, xylitol, and maltitol found in some artificial sweeteners have a laxative effect and can cause diarrhea.
Brown SR, Cann PA, Read NW. Effect of coffee on distal colon function. Gut. 1990;31(4):450-3. doi:10.1136/gut.31.4.450
Sloots CE, Felt-bersma RJ, West RL, Kuipers EJ. Stimulation of defecation: effects of coffee use and nicotine on rectal tone and visceral sensitivity. Scand J Gastroenterol. 2005;40(7):808-13. doi:10.1080/00365520510015872
US National Library of Medicine. Lactose intolerance. Updated May 2010.