Green tea consumption and the risk of stroke: A systematic review and meta-analysis of cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective cohort studies
PubMed 36599267 · doi:10.1016/j.nut.2022.111936
What was done
Systematic review and meta-analysis searching PubMed and Embase from 1966 through September 2022. Included prospective cohort studies reporting relative risk (RR) estimates and 95% confidence intervals (CIs) for green tea consumption and incident stroke. Study-specific risk estimates were combined using a random-effects model, and a dose-response analysis was conducted.
What was found
Five cohort studies were included, covering 645,393 participants and 11,421 stroke cases. Highest versus lowest green tea consumption was associated with a reduced stroke risk (summary RR: 0.74; 95% CI, 0.66-0.83). A non-linear dose-response association was observed (P for nonlinearity = 0.0000). Compared with non-consumers, stroke RRs (95% CI) were 0.91 (0.89-0.94) for 150 mL/d, 0.84 (0.80-0.89) for 300 mL/d, 0.79 (0.74-0.84) for 500 mL/d, 0.77 (0.72-0.82) for 900 mL/d, and 0.84 (0.77-0.91) for 1500 mL/d.
Why it matters
This meta-analysis quantifies an inverse, non-linear relationship between green tea intake and stroke, suggesting moderate daily consumption (around 500 to 900 mL/day) confers the greatest statistical reduction in risk.
Limits
The analysis relies on only five observational cohort studies, precluding causal inference. Residual confounding from unmeasured lifestyle or dietary factors cannot be ruled out, and the abstract does not report stroke subtypes (ischemic vs. hemorrhagic) or participant demographics.
Cited by
- supports A meta-analysis of over 500,000 people found that regular tea drinking is associated with approximately a 13% reduction in stroke risk.