A new study from APC Microbiome Ireland at University College Cork has found that regular coffee consumption—both caffeinated and decaffeinated—alters the gut microbiome, influencing mood, stress levels, and cognitive function. The research, published in Nature Communications, analyzed 62 participants, including 31 regular coffee drinkers and 31 non-drinkers, to assess the effects of coffee on gut bacteria and mental health.
Core Findings
Regular coffee drinkers (consuming three to five cups daily) exhibited higher levels of beneficial gut bacteria, such as Eggertella and Cryptobacterium curtum, which aid digestion and reduce inflammation. When coffee drinkers abstained for two weeks, their gut microbiomes changed significantly, and they reported lower stress and impulsivity. Upon reintroducing coffee, participants experienced different effects based on whether they consumed caffeinated or decaffeinated coffee. Caffeinated coffee was linked to reduced anxiety and improved attention, while decaf was associated with better sleep, memory, and physical activity.
Deeper Dive & Context
The study highlights the 'gut-brain axis,' a communication network between the digestive system and the brain. Researchers noted that coffee interacts with gut microbes, metabolism, and emotional well-being. The findings suggest that coffee's benefits extend beyond caffeine, affecting digestion and mental health through microbial changes. The study also observed that decaffeinated coffee improved learning and memory, while caffeinated coffee enhanced vigilance and reduced anxiety.
Methodology & Implications
Participants underwent psychological assessments, diet tracking, and stool and urine analysis. The study's design—including a two-week coffee abstinence period followed by reintroduction—allowed researchers to isolate coffee's effects on the gut microbiome and mental health. The findings could inform dietary recommendations for gut and brain health, though further research is needed to confirm long-term effects.