New research shows how coffee affects memory, mood, and gut health. Scientists found that regularly drinking coffee changes gut bacteria. This is linked to changes in mood, stress, and how well people think.
Coffee's Impact on Gut and Brain
Researchers at APC Microbiome Ireland, part of University College Cork, studied how coffee helps the gut-brain axis. This is the first time such a close look has been taken. The study, published in Nature Communications, found that both regular and decaf coffee can change the gut microbiome. It also affects mood and stress.
While coffee's benefits for digestion and mental well-being are known, the exact reasons were not clear. This study used many measurements to see how coffee affects the two-way communication between the gut and the brain.
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Start Your News DetoxHow the Study Worked
The study included 31 coffee drinkers and 31 non-coffee drinkers. They filled out surveys about their mood and stress. They also kept track of their caffeine and diet. Stool and urine samples were collected to check gut microbes. Coffee drinkers in the study had 3-5 cups per day, which is considered a moderate amount.
For two weeks, participants stopped drinking coffee. During this time, the regular coffee drinkers showed changes in their gut.
Then, coffee was brought back. Half the participants drank decaf coffee, and the other half drank regular coffee. Both groups reported less stress, depression, and impulsivity. This means coffee improved mood, no matter if it had caffeine or not.
Gut Bacteria and Cognitive Benefits
Coffee drinkers had more of certain bacteria, like Eggertella sp and Cryptobacterium curtum. Eggertella sp helps produce stomach and intestinal acid. Cryptobacterium curtum helps make bile acid. These functions can help remove bad gut bacteria and reduce stomach infections. Higher levels of Firmicutes bacteria were also seen, which are linked to positive feelings in women.
Only those who drank decaf coffee showed better learning and memory. This suggests that other compounds in coffee, like polyphenols, might be responsible for these brain benefits. Caffeinated coffee, however, was linked to less anxiety, better alertness, and more attention. Caffeine was also connected to a lower risk of inflammation.
Professor John Cryan, a lead researcher, noted that public interest in gut health is growing. He explained that the link between gut and mental health is becoming clearer. However, how coffee affects this link was not well understood.
He added that the findings show how coffee changes microbes and brain responses. This could lead to long-term benefits for a healthier microbiome. Coffee might change what microbes do and what they use. Professor Cryan concluded that coffee is more than just caffeine. It's a complex part of our diet that affects gut microbes, metabolism, and emotions. Both caffeinated and decaffeinated coffee can help health in different but helpful ways.
Deep Dive & References
Habitual coffee intake shapes the gut microbiome and modifies host physiology and cognition - Nature Communications, 2026
