23/09/2026
🧐Yes to that 2nd cup then
☕ Coffee may boost mood and brain function through more than just caffeine.
Researchers at University College Cork studied 62 healthy adults to explore how coffee affects the gut-brain axis — the two-way communication system linking gut microbes and the brain.
Half were regular coffee drinkers, while the others rarely or never drank coffee.
The regular drinkers first stopped coffee for 14 days, then were randomly assigned to drink either caffeinated or decaffeinated coffee for another 21 days.
Researchers collected blood, saliva, urine and stool samples and measured mood, stress, sleep, memory, attention and behaviour.
Both caffeinated and decaffeinated coffee were linked to lower perceived stress, depression and impulsivity after coffee was reintroduced.
But the two types also produced different effects.
Caffeinated coffee was associated with reduced anxiety and psychological distress, along with improvements in attention and vigilance.
Decaffeinated coffee, meanwhile, was linked to better learning and memory, improved sleep and increased physical activity.
That suggests some of coffee’s effects cannot be explained by caffeine alone.
Researchers found that coffee also rapidly changed the composition and activity of the gut microbiome.
Some cognitive improvements were associated with metabolites produced from coffee polyphenols — plant compounds that gut bacteria can transform into biologically active molecules.
But this was a relatively small study, and it does not prove that coffee or changes in gut bacteria directly caused the psychological improvements.
The researchers also note that non-coffee drinkers showed some advantages, including lower impulsivity and greater cognitive stability.
Still, the study suggests that coffee is more complex than being a caffeine delivery system.
📃 RESEARCH PAPER
📌 Boscaini et al., “Habitual coffee intake shapes the gut microbiome and modifies host physiology and cognition”, Nature Communications (2026)
