Regular coffee consumption may influence how the digestive system works, affecting intestinal contractions, bowel movements and the diversity of gut bacteria, according to research conducted by the University of Copenhagen.
The study, published in the scientific journal Gut Microbiology, examined the relationship between habitual coffee drinking and changes in the digestive system. Researchers found that people who regularly drink coffee had a more diverse gut microbiome, lower acidity levels in the small intestine and a greater number of contractions in the colon than those who consumed coffee less frequently.
To investigate these effects, the research team used a small electronic capsule that participants swallowed. The device travelled through the digestive system, collecting information about several internal conditions, including the time taken for material to pass through the gastrointestinal tract, temperature, acidity levels and intestinal contractions.
The study involved 61 healthy adults in Denmark, divided into two groups based on their coffee-drinking habits. One group consisted of people who drank between one and five cups of coffee a day on more than three of the eight days covered by the study. The other group included participants who consumed coffee less frequently.
When the researchers compared the results, they found that regular coffee drinkers had greater diversity among the microorganisms living in their intestines. These microorganisms, collectively known as the gut microbiome, include bacteria and other organisms that play important roles in digestive health.
The findings add to existing research examining how coffee consumption may influence the gut microbiome and digestive processes. Francesca Bucci, the study’s lead researcher and a PhD student in the Department of Nutrition, Exercise and Sports at the University of Copenhagen, said the results suggest that regular coffee consumption can affect intestinal physiology.
Another notable finding concerned acidity in the small intestine. Participants who regularly drank coffee had significantly lower acidity levels in this part of the digestive system compared with those who consumed it less often. However, the researchers could not establish whether this change has positive or negative effects on health.
The study also identified a relationship between coffee consumption and increased contractions in the colon. These contractions are part of the digestive system’s natural movement, helping push intestinal contents towards the rectum and supporting regular bowel movements.
Changes in colon activity can influence how quickly waste moves through the digestive tract. When these movements are functioning properly, they help maintain normal bowel habits and reduce the likelihood of constipation. Bucci noted that intestinal contractions play an important role in digestion and in maintaining the functional condition of the intestinal muscles.
Despite these findings, the researchers caution against interpreting the results as proof that drinking coffee directly causes changes in gut health. The study compared people with different coffee-drinking habits but did not control how much coffee each participant consumed.
Henrik Munch Roager, associate professor and head of the research group in the Department of Nutrition, Exercise and Sports at the University of Copenhagen, said previous research has already shown that coffee can influence several processes in the digestive system, including the secretion of stomach acids.
He believes this existing evidence supports the possibility that coffee contributes to the differences observed in the study. Many coffee drinkers also report noticing changes in their digestion after drinking it, although personal experiences alone cannot establish the biological effects.
The researchers say further investigation is needed to understand how coffee affects the digestive system and whether the observed changes have meaningful health consequences.
Their proposed next step is a controlled study in which participants would be given specific amounts of coffee rather than simply being observed according to their existing drinking habits. Such research could help establish whether coffee is directly responsible for changes in gut bacteria, intestinal acidity and colon contractions.
For now, the findings provide further evidence of a possible relationship between habitual coffee consumption and digestive function, but they do not establish that drinking more coffee improves gut health.
