But what is it about the brew that blasts your bowels? Many people think caffeine gets things going, but that may not be the case, according to the results of a preliminary study conducted in rats. Critters that drank both caffeinated and decaf coffee had less bacteria in their poop compared to rats that weren't given any coffee, reported Gizmodo . This indicates that some compound in coffee may kill off gut bacteria to have an impact on bowel movements.
Coffee has this stimulating effect on gut motility, and that is not related to caffeine at all. We could see this even with decaffeinated coffee, so its caffeine-independent, study co-author Xuan-Zheng Shi, an associate professor in internal medicine at the University of Texas Medical Branch at Galveston, explained to Gizmodo. The research has not yet been published but was presented at the Digestive Disease Week research conference, May 18-21.
Of course this study wasn't conducted in people, and much more research needs to be done before we can determine coffee messes with our gut health.
Other studies have shown that caffeine may not be the only reason we run to the bathroom. Scientists already knew that coffee causes gut contractions that activate that gotta-go urge, says Satish Rao, M.D., Ph.D., the director of the digestive health center at Georgia Regents University.
Two decades ago, Dr. Rao and his teams recruited 12 lucky people to wear anal probes with sensors that measured pressure activity throughout different parts of their colons and rectums. Over the course of 10 hours, the subjects drank the same amounts of caffeinated coffee, decaf coffee, and hot water, and ate a 1,000-calorie burger meal.
The food triggered the greatest activity in the participants guts, but the researchers were surprised to discover that caffeinated java prompted contractions of a near-similar magnitude-60 percent stronger than that of hot water, and 23 percent more intense than decaf.
This shows caffeine-a known stimulant-does play a role in jumpstarting your colon, but its not the only player involved. Theres likely something in coffee itself thats responsible for your need to go number 2, says Dr. Rao.
Experts have a theory: Just minutes after you ingest java, it reaches your stomach. One or more of its hundreds of compounds triggers the production of certain hormones in your body, such as motilin-which stimulates gut contractions-or gastrin, which causes the secretion of acid in your stomach. Thats when the pooping kicks in.
But scientists say its also possible that a combination of everything involved in your A.M. routine sends you scurrying to the toilet.
Your colon is about twice as active in the morning thanks to your bodys circadian rhythms, says Dr. Rao. Add in breakfast, wash it down with coffee-both of which independently spark colonic contractions-and you can see why youre clamoring for a crap afterward.
To avoid spending overtime in the office restroom, hold off on making your Starbucks run until about 2 hours after you wake up. This will give your colon enough time to calm down from its morning rev, Dr. Rao says.
And when you drink your first cup, try not to pair it with food or exercise, since theyll both get your gut going, too.