Fermented Tea and Cognitive Dysfunction in Diabetes: A Novel Perspective on the Gut-Brain AXIS

The interplay among diabetes, cognitive decline, and the gut microbiome represents an emerging field of scientific inquiry. The gut-brain axis serves as a crucial communication network between the gastrointestinal system and the central nervous system, playing a significant role in diabetes-related cognitive deterioration. Fermented tea, enriched with bioactive constituents, offers a promising therapeutic strategy by modulating this axis. Specifically, compounds including catechins in fermented tea positively modulate gut microbiota composition, promoting commensal bacteria while suppressing pathogenic strains. This microbial shift enhances the production of short-chain fatty acids, which may strengthen gut barrier integrity, attenuate systemic inflammation, and thereby influence cognitive health via the gut-brain axis. Concurrently, the antioxidant properties of tea polyphenols and catechins mitigate oxidative stress, a key pathogenic factor in diabetic cognitive impairment. Furthermore, the anti-inflammatory effects of fermented tea may potentially ameliorate chronic low-grade inflammation in diabetes, offering a plausible pathway for cognitive improvement. This systematic review, conducted through comprehensive searches of PubMed, Web of Science, CNKI (China National Knowledge Infrastructure), and Wanfang databases, synthesizes evidence supporting fermented tea as a natural intervention to preserve cognitive function in diabetic individuals by targeting the gut microbiome and the gut-brain axis. Notably, it also explores the potential application of Chibi Green Brick tea as a regionally specific intervention for diabetes-related cognitive dysfunction. Collectively, these insights underscore the necessity for rigorous mechanistic investigations and robust clinical validation to fully elucidate therapeutic mechanisms of fermented tea and translate these findings into clinical practice.