Researchers at APC Microbiome Ireland at University of Cork published a study in Nature Communications on Monday that compared 31 regular coffee drinkers with 31 non-coffee drinkers to test coffee’s effects on the gut-brain axis. [1]
The team said coffee consumption changed the intestinal microbiome, increasing some bacteria, including Eggerthella species and Cryptobacterium curtum, that help eliminate harmful intestinal bacteria. [1]
Lead researcher John Cryan said public interest in gut health has risen and that digestive and mental health are increasingly being better understood, but the mechanisms behind coffee’s effects on the gut-brain axis have stayed unclear. He said, "Coffee is more than just caffeine, it’s a complex dietary factor that interacts with our gut microbes, our metabolism, and even our emotional well-being." [1]
The study found the effects of coffee on the gut-brain axis appear to involve both caffeine and other compounds, with influence on gut microbes, metabolism and emotional well-being. [1]
On behavior, regular coffee drinkers in the study showed higher impulsiveness and emotional reactivity than non-drinkers. [1]
The findings were published on 2026-05-04 in Nature Communications. [1]
