New research reveals mechanisms behind coffee’s positive effects on the gut-brain axis
How does coffee affect the gut, and what does the mind have to do with it?
A new study by APC Microbiome Ireland at University College Cork, a world-leading research centre, has, for the first time, comprehensively investigated the mechanisms behind the positive effects of coffee on the gut-brain axis. Published in Nature Communications and funded by the Institute for Scientific Information on Coffee (ISIC), the study shows how regular consumption of caffeinated and decaffeinated coffee can influence the gut microbiome and, in turn, be linked to changes in mood and stress levels.
The positive effects of coffee on digestion and mood have already been studied, but the exact mechanisms behind these effects have not yet been fully understood. This study therefore used various measurement methods to analyse how coffee consumption affects the gut-brain-microbiota axis – in other words, the ‘communication’ between the gut microbiome and the brain.
How the study was conducted – and what it revealed
The study involved 31 coffee drinkers and 31 non-coffee drinkers, who were assessed using a series of psychological tests, caffeine and food diaries, and stool and urine samples. The aim was to record changes in the microbiome, as well as in perceived mood and stress levels. ‘Coffee drinkers’ were defined as people who regularly consume 3–5 cups of coffee per day – a quantity classified by the European Food Safety Authority (EFSA) as safe and moderate for most people.
At the start, participants abstained from coffee for two weeks. Among regular coffee drinkers, this withdrawal period led to significant changes in the metabolite profiles of the gut microbiome compared to non-coffee drinkers.
Regular coffee drinkers were then given coffee again in a blind trial: one group consumed decaffeinated coffee, the other caffeinated coffee. Both groups reported lower levels of perceived stress, depressive mood and impulsivity. This suggests that coffee consumption can have a positive effect on mood, regardless of the caffeine content.
Effects on gut flora and mental performance
The researchers also found differences in the microbiome: certain bacteria, which play a significant role in eliminating harmful gut bacteria and infections, were more common among coffee drinkers. Bacteria associated with positive emotions were also more common in women.
The picture was more nuanced when it came to cognitive effects: improvements in learning and memory were observed only after the consumption of decaffeinated coffee, suggesting a possible role for other compounds such as polyphenols. Caffeinated coffee, on the other hand, was associated with reduced anxiety and improved alertness and attention.
Professor John Cryan, lead researcher at APC Microbiome Ireland and corresponding author of the study, explained that public interest in gut health has risen sharply in recent years. The link between digestion and mental health is also being increasingly better understood. The findings revealed microbiome and neurological responses to coffee, as well as its potential to contribute to a healthy digestive balance as part of a healthy, balanced diet.
About ISIC
The Institute for Scientific Information on Coffee (ISIC) is dedicated to contributing and consolidating balanced scientific information on coffee consumption – providing a reference for professionals and authorities who address health and wellbeing.
ISIC respects scientific research ethics in all its activities. ISIC’s communications are based on sound science and rely on scientific studies derived from peer-reviewed scientific journals and other publications.
ISIC members are five of the major European coffee companies: illycaffè, JDE Peet’s, Lavazza, Paulig and Tchibo.
more informations about ISIC: www.coffeeandhealth.org
