Study: Coffee Reshapes Gut Microbiome, Improves Mood

A new study from researchers at University College Cork in Ireland has found that regular coffee consumption, whether caffeinated or decaffeinated, can reshape the gut microbiome and improve mood while reducing stress levels. The research, involving 31 habitual coffee drinkers and an equal number of non-drinkers, highlights how the beverage influences the microbiota-gut-brain axis, the bidirectional communication between gut bacteria and the brain that affects overall health.

Led by Professor John Cryan, principal investigator at APC Microbiome Ireland, the team monitored participants over two weeks of coffee abstinence followed by reintroduction of the beverage in a blinded trial. Habitual drinkers, defined as those consuming three to five cups daily—a level deemed safe by the European Food Safety Authority—underwent psychological assessments, food and caffeine diaries, and provided stool and urine samples to track microbiome changes and stress markers. During abstinence, coffee drinkers showed significant shifts in gut metabolites compared to non-drinkers, indicating the beverage's ongoing impact on microbial activity.

Upon reintroducing coffee, half the participants received...