Scientists Discover How Coffee Impacts Memory, Mood, and Gut Health
By University College Cork
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The study, published in Nature Communications and
supported by the Institute for Scientific Information on Coffee (ISIC), shows
that regularly drinking both caffeinated and decaffeinated coffee can shape the
gut microbiome and influence mood and stress.
Although coffee’s benefits for digestion and mental
well-being are well known, the biological processes behind these effects have
not been fully understood. This study explored how coffee affects the
microbiota-gut-brain axis, the two-way communication system linking the gut
microbiome and the brain, using a wide range of measurements.
Study Design and Participant Analysis
The research followed 31 coffee drinkers and 31 non-coffee
drinkers using psychological evaluations, caffeine and diet logs, and stool and
urine samples to track changes in gut microbes and self-reported mood and
stress. “Coffee drinkers” were defined as individuals who regularly consume 3-5
cups per day, an amount considered safe and moderate for most people by the
European Food Safety Authority (EFSA).
Participants then avoided coffee for two weeks while
continuing psychological assessments and biological sampling. During this
period, regular coffee drinkers showed clear shifts in gut metabolite profiles
compared to non-coffee drinkers.
After this phase, coffee was reintroduced in a blinded
setup. Half of the participants received decaffeinated coffee, while the others
consumed caffeinated coffee. Both groups reported lower levels of stress,
depression, and impulsivity, indicating that coffee improved mood regardless of
caffeine content.
Microbiome Changes and Beneficial Bacteria
Certain bacteria, including Eggertella sp and Cryptobacterium
curtum, were found in higher levels among coffee drinkers than non-coffee
drinkers. Eggertella sp is believed to support gastric and
intestinal acid production, while Cryptobacterium curtum plays
a role in bile acid synthesis. These functions may help remove harmful gut
bacteria and reduce stomach infections. Higher levels of Firmicutes bacteria
were also observed, which have been linked to positive emotional states in
females.
Only participants who consumed decaffeinated coffee showed
clear improvements in learning and memory, suggesting that compounds other than
caffeine, such as polyphenols, may drive these cognitive effects. In contrast,
caffeinated coffee was associated with reduced anxiety along with better
alertness and attention. Caffeine was also linked to a lower risk of
inflammation.
Expert Insights on Coffee and Health
Corresponding author of the study, Professor John Cryan,
Principal Investigator at APC Microbiome Ireland, University College Cork,
commented, “Public interest in gut health has risen hugely. The relationship
between digestive and mental health is also increasingly being better
understood, but the mechanisms behind coffee’s effects on this gut-brain axis
have remained unclear.
“Our findings reveal the microbiome and neurological
responses to coffee, as well as their potential long-term benefits for a
healthier microbiome. Coffee may modify what microbes do collectively and what
metabolites they use. As the public continues to think about dietary changes
for the right digestive balance, coffee has the potential to also be harnessed
as a further intervention as part of a healthy, balanced diet.”
“Coffee is more than just caffeine—it’s a complex dietary
factor that interacts with our gut microbes, our metabolism, and even our
emotional well-being,” said Professor Cryan. “Our findings suggest that coffee,
whether caffeinated or decaffeinated, can influence health in distinct but
complementary ways.”
Reference: “Habitual coffee intake shapes the gut microbiome
and modifies host physiology and cognition” by Serena Boscaini, Thomaz F. S.
Bastiaanssen, Gerard M. Moloney, Federica Bergamo, Laila Zeraik, Caroline
O’Leary, Aimone Ferri, Maha Irfan, Maaike van der Rhee, Thaïs I. F. Lindemann,
Elizabeth Schneider, Arthi Chinna Meyyappan, Kirsten Berding Harold, Caitríona
M. Long-Smith, Carina Carbia, Kenneth J. O’Riordan, José Fernando Rinaldi de
Alvarenga, Nicole Tosi, Daniele Del Rio, Alice Rosi, Letizia Bresciani, Pedro
Mena, Gerard Clarke and John F. Cryan, 21 April 2026, Nature
Communications.
DOI:
10.1038/s41467-026-71264-8
