And he said it’s not uncommon for patients who have given up coffee for one reason or another to tell him, “Doc, I can’t go to the bathroom without a coffee.” Martindale also suggests coffee, along with other dietary changes, when he counsels patients with chronic constipation.
Martindale, who routinely offers his patients a cup of coffee the morning after surgery.ĭr. Researchers have hypothesized that coffee’s gut-brain messaging is likely caused by one or more of coffee’s many chemicals, and perhaps mediated by some of our own hormones that play important roles in the digestive process, like gastrin or cholecystokinin - both of which can spike after coffee drinking. But coffee seems to have an outsize effect one study published in 1998 found that eight ounces of coffee stimulated colonic contractions similar to those induced by a 1,000-calorie meal. This communication between the stomach, brain and colon, called the gastrocolic reflex, is a normal response to eating. The coffee itself would move through the intestines much more slowly, likely taking at least an hour to traverse the long path from the stomach through the small intestine and to the colon. That is, the arrival of coffee in the stomach sends a message to the brain, which then “stimulates the colon to say, ‘Well, we’d better empty out, because things are coming downstream,’” he explained. That drinking a cup of coffee can stimulate the opposite end of the gastrointestinal tract within minutes means “it’s probably going through the gut-brain axis,” Dr. Among those who said that coffee usually stimulated a bowel movement, the probe showed a significant increase in pressure within four minutes of drinking coffee, while the so-called nonresponders had no change in colon activity. In the same study, some volunteers agreed to have a pressure-sensing probe inserted into their colon to measure intestinal muscle contractions before and after drinking a cup of Joe. We also know that a gut response to coffee can happen fast. Martindale said that the percentage of people who have a bowel response after drinking coffee is likely much higher in the general population - he estimated that around 60 percent of his patients do - and he hasn’t noticed any differences between men and women.) In one study published in 1990 in the journal Gut, 92 young adults filled out a questionnaire about how coffee affected their bowel habits just 29 percent of the respondents said it “induced a desire to defecate,” and most of them - 63 percent - were female. One thing we do know is that coffee doesn’t affect everyone the same way. And determining how they affect the intestines is challenging. One paper published in 1998, for instance, found that decaffeinated coffee had a similar stimulatory effect on the colon as caffeinated coffee, whereas a cup of hot water did not.Ĭoffee is a complex beverage containing more than 1,000 chemical compounds, many of which have antioxidant and anti-inflammatory properties. Some studies on the topic - which tend to be small, old and limited - have suggested that it’s probably not the caffeine that triggers the urge to go. Robert Martindale, a professor of surgery and the medical director for hospital nutrition services at Oregon Health and Science University. This satisfying brew revs energy levels with a dose of caffeine and, for many people, quickly and reliably jump-starts gut activity and an urgent need to poop.īut given coffee’s popularity, it’s surprising that we know so little about how it affects the gastrointestinal tract, said Dr. Like opening the blinds and stepping into the shower, a cup of coffee gets people moving in the morning - in more ways than one.