New Irish study finds both caffeinated and decaffeinated coffee improve gut health, mood, and cognitive function through microbiome-related changes.
A study conducted in Ireland has shown that even decaffeinated coffee can positively impact gut health, mood, and cognitive performance. Researchers from University College Cork compared health indicators of 31 individuals who consumed three to five cups of coffee daily with 31 participants who did not drink coffee.
At the outset, no significant differences were observed between the two groups in terms of body mass index, blood pressure, stress, anxiety, depression, gastrointestinal symptoms, sleep quality, or physical activity. However, notable changes were later identified in immune markers within the blood and in specific microbial species present in the gut of coffee drinkers.
CONTROLLED TESTING OF CAFFEINE EFFECTS
To determine whether caffeine itself was responsible for these outcomes, researchers asked the coffee-consuming group to abstain from coffee for two weeks. Following this phase, participants resumed coffee intake under controlled conditions: 16 individuals consumed caffeinated coffee while 15 consumed decaffeinated coffee over a three-week period, without knowing which type they were drinking.
After reintroduction, changes associated with coffee consumption were observed in the gut microbiome of all participants, including species-level variations linked to both caffeinated and decaffeinated coffee. The authors concluded that both forms of coffee reduced stress, depression, impulsivity, and inflammation, while also enhancing mood and cognitive performance.
IMPACTS ON GUT-BRAIN AXIS
The findings suggest that caffeinated coffee is associated with reduced anxiety, lower psychological distress, decreased blood pressure, improved attention, and enhanced stress resilience. However, individuals who consumed coffee displayed higher impulsivity and emotional reactivity compared to non-drinkers, both at baseline and after caffeine reintroduction.
In contrast, decaffeinated coffee was linked to improvements in sleep quality, physical activity levels, and memory. These results indicate that while caffeine may play a role in shaping mood and cognition, decaffeinated coffee may still influence the gut-brain connection independently.
Microbiologist John Cryan emphasized that coffee should not be viewed solely as a source of caffeine, describing it as a complex dietary component that interacts with gut microbes, metabolism, and emotional well-being. He noted that the findings demonstrate how both caffeinated and decaffeinated coffee can affect health in distinct yet complementary ways.
LIMITATIONS AND FUTURE INSIGHTS
The study acknowledged that its conclusions are based on associations between microbial changes and self-reported mood and behavioral shifts, which may not fully capture causal relationships. Nonetheless, the research relied on a detailed analysis comparing how participants metabolized coffee compounds and linking these differences to metabolic patterns within the gut microbiome.
Cryan also highlighted that much remains unknown about the gut microbiome, noting that while the relationship between digestion and mental health is becoming clearer, the mechanisms underlying coffee’s effects on the gut-brain axis are still not fully understood.