A major new study has found that regular consumption of coffee significantly boosts mood and improves concentration, while also reducing anxiety. Researchers at APC Microbiome Ireland, a world-leading centre at University College Cork, discovered that both caffeinated and decaffeinated coffee alter the gut microbiome in ways that improve perceived mood and stress levels.
The study, published in Nature Communications, is the first of its kind to explore how coffee affects the microbiota–gut–brain axis. It followed 31 regular coffee drinkers and 31 non-coffee drinkers through psychological assessments, dietary diaries, and biological sampling. After two weeks of abstaining from coffee, the regular drinkers showed significant shifts in their gut microbiome compared to non-drinkers.
When coffee was reintroduced to both groups, with half receiving caffeinated and half decaffeinated, participants reported lower perceived stress, depression, and impulsivity. Notably, improvements in learning and memory were seen only in those drinking decaffeinated coffee, suggesting that compounds such as polyphenols may drive certain cognitive benefits. Caffeinated coffee, meanwhile, was associated with reduced anxiety, heightened vigilance and attention, and lower inflammation risk.
Professor John Cryan, principal investigator at APC Microbiome Ireland and co-author of the study, 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 wellbeing. Our findings suggest that coffee, whether caffeinated or decaffeinated, can influence health in distinct but complementary ways.'
