Tea intake or consumption and the risk of dementia: a meta-analysis of prospective cohort studies

PeerJ. 2023 Jul 18:11:e15688. doi: 10.7717/peerj.15688. eCollection 2023.

Abstract

Purpose: Dementia affects as many as 130 million people, which presents a significant and growing medical burden globally. This meta-analysis aims to assess whether tea intake, tea consumption can reduce the risk of dementia, Alzheimer's disease (AD) and Vascular dementia (VD).

Patients and methods: Cochrane Library, PubMed and Embase were searched for cohort studies from inception to November 1, 2022. The Newcastle Ottawa Quality Assessment Scale (NOS) was applied to evaluate the risk of bias of the included studies. We extracted the data as the relative risks (RRs) for the outcome of the interest, and conducted the meta-analysis utilizing the random effect model due to the certain heterogeneity. Sensitivity analysis were performed by moving one study at a time, Subgroup-analysis was carried out according to different ages and dementia types. And the funnel plots based on Egger's and Begger's regression tests were used to evaluate publication bias. All statistical analyses were performed using Stata statistical software version 14.0 and R studio version 4.2.0.

Results: Seven prospective cohort studies covering 410,951 individuals, which were published from 2009 and 2022 were included in this meta-analysis. The methodological quality of these studies was relatively with five out of seven being of high quality and the remaining being of moderate. The pooling analysis shows that the relationship between tea intake or consumption is associated with a reduced risk of all-cause dementia (RR = 0.71, 95% CI [0.57-0.88], I2 = 79.0%, p < 0.01). Further, the subgroup-analysis revealed that tea intake or consumption is associated with a reduced risk of AD (RR = 0.88, 95% CI [0.79-0.99], I2 = 52.6%, p = 0.024) and VD (RR = 0.75, 95% CI [0.66-0.85], I = 0.00%, p < 0.001). Lastly, tea intake or consumption could reduce the risk of all-cause dementia to a greater degree among populations with less physical activity, older age, APOE carriers, and smokers.

Conclusion: Our meta-analysis demonstrated that tea (green tea or black tea) intake or consumption is associated with a significant reduction in the risk of dementia, AD or VD. These findings provide evidence that tea intake or consumption should be recognized as an independent protective factor against the onset of dementia, AD or VD.

Keywords: Alzheimer’s disease; Prospective cohort study; System evaluation; Tea drinking.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / prevention & control
  • Camellia sinensis
  • Cohort Studies
  • Dementia / prevention & control
  • Dementia, Vascular / prevention & control
  • Humans
  • Prospective Studies
  • Tea*

Substances

  • Tea

Grants and funding

This work was supported by the National Natural Science Foundation of China (No. 61263033), the International Science and Technology Cooperation Project of Hainan (No. KJHZ2015-4), the Higher School Scientific Research Project of Hainan Province (No. Hnky2015-80), the Research program of Medical and Health Science and Technology Development Plan Project of Shandong Province (No. 202103070653), the Natural Science Foundation of Shandong Province (No. ZR2022MH124), the Youth Science Foundation of Shandong First Medical University (No. 202201-105), the Shandong Medical and Health Technology Development Fund (No. 202103070325), the Shandong Province Traditional Chinese Medicine Science and Technology Project (No. M-2022216) and the Nursery Project of the Affiliated Tai’an City Central Hospital of Qingdao University (No. 2022MPM06). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.