Tea and Blood–Brain Barrier Homeostasis: Potential Mechanisms and Improvement Strategies

The blood–brain barrier (BBB), a selective interface regulating cerebral substance exchange, plays a crucial role in maintaining cognitive function and metabolic balance. While tea consumption has been traditionally associated with health benefits, its specific effects on BBB integrity warrant systematic investigation. This review demonstrates that tea bioactive compounds can cross the BBB through systemic absorption and metabolism, with their permeability determined by physicochemical properties, including molecular weight and lipophilicity. Notably, the tea bioactive compounds exhibit strong functional properties but low bioavailability. On one hand, tea can directly modulate the development of the BBB through vascular endothelial growth factor (VEGF), Wnt, and Notch1 signaling pathways, and delay BBB aging and dysfunction by alleviating CNS inflammation, oxidative stress, and p‐glycoprotein (P‐gp) activity. On the other hand, tea indirectly influences BBB homeostasis via gut microbiota‐mediated pathways, by regulating circadian rhythm disruptions, reducing psychosocial stress, and preventing metabolic syndrome. The review also discusses potential strategies to enhance tea's BBB‐protective effects, including optimization of tea leaf processing, beverage production, and nanoencapsulation of bioactive compounds. These findings provide valuable insights into the tea–BBB interaction and establish a theoretical framework for future research. This framework will support the development of dietary interventions for brain health.