Coffee doesn’t just impact your energy levels first thing in the morning; it also influences the makeup of the gut microbiota, which in turn could influence mood and stress levels. This is according to new research from APC Microbiome Ireland, a research center based at University College Cork, in Ireland.
The study is published in Nature Communications . “Coffee is more than just caffeine,” said study author John Cryan , PhD, Principal Investigator at APC Microbiome Ireland, in a press release .
“It’s a complex dietary factor that interacts with our gut microbes, our metabolism, and even our emotional well-being.” The term gut microbiota refers to all the different micro-organisms such as bacteria that live inside the digestive tract. They are a vital part of the gut microbiome, which refers not only to the microbes but also the environment they live in.
Research has already established that there is a two-way relationship between the gut and the brain, known as the gut-brain axis .
This report summarizes a human experimental study from APC Microbiome Ireland (University College Cork) published in Nature Communications that examined how habitual coffee consumption, a short-term period of coffee (and caffeine) abstinence, and subsequent reintroduction of either caffeinated or decaffeinated coffee affect mood-related measures and gut-related biological sampling.
The authors framed the work against existing interest in gut–brain interactions and prior observational links between coffee consumption and health outcomes.
The report does not list specific questionnaire instruments or laboratory assays in the source text.
The coffee-drinking cohort ceased all coffee and other dietary sources of caffeine (examples cited: sodas, dark chocolate) for 14 days.
Following that abstinence period, participants were randomized in a blinded fashion to reintroduce either decaffeinated coffee (n = 15) or caffeinated coffee (n = 16) for a 21-day intervention.
The prescribed intake during reintroduction was four sachets of instant coffee per day.
Repeated assessments were performed during the abstinence phase and through the three-week reintroduction period.
The source does not present details of laboratory endpoints or microbiota analytic methods in this summary.
Self-report instruments showed reductions in stress, depression, and impulsivity after resumption of either coffee type.
The authors emphasize that coffee contains multiple bioactive constituents beyond caffeine that can interact with gut microbes and host metabolism.
Therefore, effect sizes, statistical significance, and robustness of the associations are not reported here.
The source does not report on safety events, microbiome compositional changes, or whether specific coffee constituents mediated distinct effects.
Detailed quantitative results, methods for microbiome analyses, and broader causal inferences were not included in the source summary.