Abstract
Our present knowledge about the efficacy of tea consumption in improving age-related cognitive disorders is incomplete since previous epidemiological studies provide inconsistent evidence. This unified systematic review and meta-analysis based on updated epidemiological cohort studies and randomized controlled trials (RCTs) evidence aimed to overcome the limitations of previous reviews by examining the efficacy of distinct types of tea consumption. PubMed, Embase, and MEDLINE were searched up to May 20, 2022, and 23 cohorts and 12 cross-sectional studies were included. Random-effects meta-analyses were conducted to obtain pooled RRs or mean differences with 95% CIs. The pooled RRs of the highest versus lowest tea consumption categories were 0.81 (95% CIs: 0.75–0.88) and 0.69 (95% CIs: 0.61–0.77), respectively. The pooled mean difference of four included RCTs revealed a beneficial effect of tea on cognitive dysfunction (MMSE ES: 1.03; 95% CI, 0.14–1.92). Subgroup analyses further demonstrated that green and black tea intake was associated with a lower risk of cognitive disorders in eastern countries, especially in women. The evidence quality was generally low to moderate. The present review provides insight into whether habitual tea consumption can be an effective approach against age-related neurodegenerative cognitive disorders and summarizes potential mechanisms based on currently published literature.
Duality of interest
The authors declare that there is no duality of interest associated with this manuscript.
Author contribution
WQ designed the research. WQ and MqL did the literature search. YL and HyZ reviewed studies for inclusion and performed data extraction and checking. WQ and JL performed meta-analyses. WQ, MmZ, and ZyH contributed to the interpretation of data. WQ drafted the article. JC and ZhL contributed to the critical revision of the manuscript for important intellectual content. All authors approved the final manuscript. WQ is the guarantor of this work.
Disclosure statement
No potential conflict of interest was reported by the authors.