Small study links coffee to gut and mood changes

A small study of 62 adults found that habitual coffee drinking was associated with changes in gut bacteria and metabolites, while both caffeinated and decaffeinated coffee were linked to lower reported stress, depression and impulsivity after a two-week break. The results do not show that coffee caused the changes or that it treats mental-health conditions. Researchers at APC Microbiome Ireland and University College Cork compared 31 habitual coffee drinkers with 31 people who did not regularly drink coffee. The habitual drinkers typically consumed three to five cups a day. After the coffee drinkers abstained for two weeks, researchers reintroduced either caffeinated or decaffeinated coffee and tracked participants’ gut microbes, metabolites and psychological measures. The study, published in Nature Communications, reported changes in gut bacteria including Eggertella species, Cryptobacterium curtum and members of the Firmicutes group. Metabolite profiles also shifted during abstinence and after coffee was reintroduced.