However, the health benefits of coffee are not only due to caffeine. Coffee contains polyphenolic compounds that have antioxidant properties on the one hand, and are metabolized by gut bacteria on the other hand. In the study it is mentioned that

"The strong association of L. asaccharolyticus with coffee independently of caffeine indicates that it may also be responding to activities within these polyphenol metabolism pathways."

I find it fascinating that scientists are able to unravel these connections one after the other. I also like both, coffee and tea.