Habitual coffee intake shapes the gut microbiome and modify cognition

This study found that people who regularly drink coffee have a distinct gut microbiome and show higher impulsivity and emotional reactivity compared to non-coffee drinkers, with some of these differences reversing when coffee was stopped. However, the group who never drank coffee was much more ethnically diverse than the coffee-drinking group, which could partly explain the microbiome differences independent of coffee itself.

• Small groups: The treatment arms had only 15-16 people each - too few to draw firm conclusions about memory or cognitive benefits
• Cause vs. association: Coffee drinkers and non-drinkers may differ in genetics and background; the study cannot prove coffee caused the brain or microbiome changes
• Caffeine vs. coffee: Many cognitive improvements appeared only in the decaffeinated group, not from caffeine itself, adding complexity to the claim
• Industry funding: The study was funded by a coffee industry trade body, which is a reason to interpret positive findings with extra caution
• Descriptive conclusion: While the study proved that the gut bacteria composition and key metabolites exhibit statistically significant differences, its functional significance remains to be determined.