Regular Coffee Drinking Linked to Gut Bacteria Diversity and Colon Changes, Copenhagen Study Finds

A study by the University of Copenhagen has found that drinking coffee regularly may affect the functioning of the digestive system, especially bowel movements and colon contractions, and is also linked to greater diversity of gut bacteria. The study was published in the journal Gut Microbiology, which specialises in research on gut microorganisms.

The research team used a small electronic capsule that participants swallowed to track changes as it travelled through the digestive system. The capsule measured indicators including the time contents took to pass through the gastrointestinal tract, temperature, acidity levels and intestinal contractions.

The study involved 61 healthy adults in Denmark, divided into two groups according to how much coffee they consumed. The first group drank between one and five cups a day on more than three of the eight days covered by the study, while the second group drank coffee less frequently.

The results showed that people who consume coffee regularly have greater diversity in the microorganisms present in their intestines compared with participants who drink less coffee. The researchers said this is consistent with research suggesting coffee may influence the composition of the gut microbiome, the community of bacteria and other microorganisms that live inside the digestive system.

Francesca Bucci, the lead researcher and a PhD student in the Department of Nutrition, Exercise and Sports at the University of Copenhagen, said regular coffee consumption seems to affect the physiology of the intestines.

One of the most notable results was that people who drink coffee regularly had much lower acidity levels in the small intestine than those who consume it less often.

The researchers also observed a link between higher coffee intake and a greater number of contractions in the colon. These muscle movements help push intestinal contents through the digestive system, play a role in digestion and in keeping bowel movements regular, and may help prevent constipation and keep the intestinal muscles in good condition, the study said.

By contrast, the researchers are still unable to determine whether the lower level of acidity in the small intestine benefits health or could have negative effects.

The researchers stress that the study cannot prove that coffee consumption is the direct cause of the changes observed in the digestive system.

Henrik Munch Roager, associate professor and head of the research group in the same department, believes there are reasons to support the possibility that coffee plays a role. He said previous studies have shown coffee affects processes inside the digestive system, including the secretion of acids in the stomach, and that many people notice from daily experience that coffee affects their digestion.

The research team sees the next step as a study that allows control over the amount of coffee participants drink, instead of merely observing their habits. Such a study would help determine whether coffee is actually causing these changes and understand the mechanisms through which it may affect bowel movements and contractions.