Your daily cup of coffee could have long-term impact on gut health, study finds

Drinking coffee every day, like two-thirds of Americans, may not only improve your gut bacteria but the function of the gut itself, according to a study published Tuesday.

People who consumed 1-5 cups of coffee, more than three days a week, had higher acidity levels in their small intestine and more contractions in the colon which could impact digestive health, say researchers at the University of Copenhagen.

“Contractions in the gut can support healthy digestion, help prevent constipation and keep the intestinal muscles in good condition,” author Francesca Bucci, a PhD student at the school, said in a statement.

Bucci and her fellow researchers are not yet certain if the higher acidity levels are beneficial or harmful. However, they noted that the acidity level in the small intestine, or “pH,” plays an important role in how the body breaks down food.

The researchers also aren’t sure if the changes they observed in coffee drinkers are caused solely by a cup of joe but past research seems to support that conclusion, Henrik Munch Roager, an associate professor, said.

“For example, we already know from other studies that coffee can influence a range of processes in the digestive system, including acid secretion in the stomach. So there are good reasons to believe that what we are seeing is not merely coincidence,” he added.

The new study’s results also confirmed findings in 2024 research from the University of Texas Medical Branch that coffee positively affects the balance of gut bacteria, leading to a healthy diversity of species. A diverse gut is more flexible and able to fight off different pathogens, experts at Louisiana State University say.

A smart pill

The nine-day study included more than 60 adults, 50 of whom swallowed a sensor known as a “SmartPill.” Inside the body, the wireless capsule sent measurements of acidity, temperature, pressure, transit time and intestinal contractions to researchers.

The participants also reported everything they ate and drank over eight days, and provided daily stool and urine samples so researchers could analyze the make-up of their gut bacteria and levels of coffee-related hallmarks in the body, such as caffeine metabolites.

Caffeine conundrum

More research is needed to understand what happens to gut function during periods of high coffee consumption versus periods without coffee.

The study authors hope their findings could point the way toward better treatment for constipation, a digestive condition that affects 16 percent of adults and a third of those aged 60 and older, according to the National Institute of Health.

“A great many people struggle with constipation and irregular bowel movements. If we can understand how coffee affects digestion and intestinal contractions, it may be possible to use that knowledge to stimulate gut motility in a natural way,” said Roager. “That would be extremely valuable.”