Aging-associated cognitive dysfunction has a great influence on the lifespan and healthspan of the elderly. Theaflavins (TFs), a mixture of ingredients formed from enzymatic oxidation of catechins during the manufacture of tea, have a positive contribution to the qualities and antiaging activities of black tea. However, the role of TFs in mitigating aging-induced cognitive dysfunction and the underlying mechanism remains largely unknown. Here, we find that TFs effectively improve behavioral impairment via the microbiota-gut-brain axis: TFs maintain gut homeostasis by improving antioxidant abil...