Coffee's real driver? Gut microbes shaping mood and memory, not caffeine

A May 2026 Nature Communications study from APC Microbiome Ireland found that coffee—caffeinated or decaffeinated—modulates the gut microbiome and downstream brain signals via the gut-brain axis. Decaf coffee improved learning and memory, while caffeinated coffee reduced anxiety and boosted attention; effects persisted only with ongoing coffee consumption and disappeared during abstinence. The results point to polyphenols and other non-caffeine compounds as the cognitive drivers, underscoring that coffee rituals may influence brain health through microbiome-mediated pathways rather than caffeine alone.