Overview
- Nature Communications published the peer-reviewed study Tuesday, reporting that both types of coffee changed gut bacteria and were tied to lower perceived stress, depression and impulsivity.
- The controlled trial tracked 31 habitual drinkers and 31 non-drinkers, asked drinkers to stop coffee for two weeks, then reintroduced caffeinated or decaf coffee in a blinded setup.
- Only caffeinated coffee was linked to less anxiety along with sharper vigilance and attention in testing.
- Learning and memory improved only with decaf, pointing to non-caffeine compounds such as polyphenols as likely drivers.
- Microbial shifts included higher Eggerthella and Cryptobacterium, but the authors flagged the small sample, short window and funding from the Institute for Scientific Information on Coffee, and they called for larger independent studies.