Coffee Impacts Gut Microbiome, Mood, and Cognition

New research reveals how both caffeinated and decaffeinated coffee influence the gut-brain axis. Scientists at University College Cork found that regular coffee consumption reshapes gut bacteria. These changes are linked to improvements in mood and reduced stress levels. The study highlights coffee's effects beyond just its caffeine content.

The research, published in *Nature Communications*, examined 31 regular coffee drinkers and 31 non-coffee drinkers. Participants provided biological samples and completed psychological assessments. Coffee drinkers abstained for two weeks, then reintroduced either caffeinated or decaffeinated coffee. Both groups reported better mood, including lower stress, depression, and impulsivity.

Specific gut bacteria were more prevalent in coffee drinkers. Levels of *Eggertella sp* and *Cryptobacterium curtum* increased with coffee intake. These microbes contribute to digestive processes and may offer protection against harmful bacteria. An increase in *Firmicutes*, a bacterial group associated with positive emotions in women, was also observed.

Decaffeinated coffee improved learning and memory. This suggests that compounds other than caffeine, such as polyphenols, offer cognitive benefits. Caffeinated coffee led to reduced anxiety and enhanced attention and alertness. Caffeine also correlated with a lower risk of inflammation.

Professor John Cryan, a principal investigator at APC Microbiome Ireland, explained the findings. He noted that coffee modifies microbial activity and metabolite use. This research suggests coffee could be a dietary intervention for a healthier microbiome. Coffee interacts with gut microbes, metabolism, and emotional well-being in distinct ways.