If you were to poll the populous, you would find a huge percentage of people reporting that their morning is made much easier by a piping hot cup of coffee. It can help you feel alert, take the chill out of your bones on a cold morning, and get you ready to begin the day. More than just a caffeinated beverage that can jumpstart your day, however, it has been proven by researchers that coffee can also jumpstart a specific part of your digestive system—your bowels.
You may fall into the category of coffee-drinkers who already recognize this effect. If you rely on your daily cup of coffee to send you to the bathroom, you should know that you’re not alone. According to a study done by researchers Brown, Cann, and Read, about 29% of people they polled reported that drinking coffee caused them to feel the sudden need to defecate. While this percentage of responders represents a sizable group, however, it is far from a majority. Brown and his fellows were intrigued by the responders who admitted that coffee made them have to poop, and they set out to do a little more research into why this was the case. The results they found were surprisingly physiological rather than purely psychological.
Of those people who responded to the researchers’ initial poll, 14 were chosen to participate in the physical study. Eight of the participants reported regularly feeling the urge to defecate after drinking coffee while the other six had never had this experience. The method of research is slightly graphic, but all of the subjects had an anal probe inserted by researchers. These probes were similar to the ones used in sigmoidoscopies, a procedure similar to a colonoscopy, but which only looks at the lower portion of the colon, known as the rectosigmoid. Equipped with an apparatus that could measure the amount of muscle constriction inside the rectosigmoid after various stimuli were applied, the probes were able to physically deduce the effect coffee consumption had on bowel activity. This effect was measured in three phases. First, subjects drank a glass of hot water. A little later, they drank some caffeinated coffee, and then finally, they drank a cup of decaffeinated coffee. Any increases in bowel contractions after each beverage was consumed were measured on a scale known as the motility index.
The results of the study proved exactly what it set out to show. All of the responders who had never felt any increased need to poop after drinking coffee had no change in their bowel motility after drinking either the water or either type of coffee. The subjects who had associated coffee with defecation had no change in their motility with the cup of hot water, but both caffeinated and decaffeinated coffee caused their bowel contractions to spike (which would be associated with an increased desire to head to the bathroom).
While scientists were baffled at the time of the study as to what key ingredient in coffee was causing this reaction (since it clearly wasn’t the caffeine), further research has revealed that the answer is likely hormonal. Since the effect happens so instantaneously, it is very unlikely that the coffee physically reaches your colon or even your bloodstream before it makes you have to run to the toilet. Instead, it appears that coffee—regardless of its caffeine level—releases some chemicals from the brains of affected individuals which send a motor response to your colon. This reaction also explains why the mere smell of coffee can be enough to set some people’s bowels churning.
While less than one-third of the population feels the association of coffee with defecation, the relationship is still interesting in that it has both neurological and physiological elements. Many of you will likely be baffled by the entire premise (likely the two-thirds of you who have never particularly thought coffee made your need to poop), but for those of you who have always felt the correlation, it is certainly comforting to know that it’s not all in your head.
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Posted on: 2013-06-27 12:00 AM 
