Effects of supplementation with green tea catechins on plasma C-reactive protein concentrations: A systematic review and meta-analysis of randomized controlled trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 26233863 · doi:10.1016/j.nut.2015.02.004
What was done
The authors conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) searched through October 26, 2014, to evaluate the effect of green tea catechin supplementation on plasma C-reactive protein (CRP) concentrations. Two independent reviewers extracted study data across 11 RCT arms. Pre-specified subgroup analyses evaluated trial duration (<8 weeks vs. ≥8 weeks), catechin dosage (<400 mg/day vs. ≥400 mg/day), and baseline participant health status (healthy individuals vs. patients with cardiometabolic diseases).
What was found
Meta-analysis of 11 RCT arms showed no significant effect of green tea catechin supplementation on plasma CRP concentrations (weighted mean difference [WMD] = 0.085 mg/L; 95% CI, -0.225 to 0.395; P = 0.592). The null finding remained consistent across all subgroups: - Duration <8 weeks: WMD = 0.029 mg/L (95% CI, -0.229 to 0.286; P = 0.828) - Duration ≥8 weeks: WMD = 0.099 mg/L (95% CI, -0.555 to 0.754; P = 0.766) - Dose <400 mg/day: WMD = 0.073 mg/L (95% CI, -0.251 to 0.398; P = 0.658) - Dose ≥400 mg/day: WMD = 0.213 mg/L (95% CI, -0.148 to 0.574; P = 0.247) - Healthy participants: WMD = -0.028 mg/L (95% CI, -0.216 to 0.160; P = 0.769) - Cardiometabolic disease: WMD = 0.260 mg/L (95% CI, -0.815 to 1.334; P = 0.636) Sensitivity analyses omitting individual studies did not alter the result.
Why it matters
Despite preclinical hypotheses that green tea reduces systemic inflammation, pooled clinical trial evidence does not support a meaningful effect of green tea catechins on circulating CRP levels.
Limits
The abstract does not report total participant counts or specific catechin formulations (e.g., pure EGCG vs. mixed extracts). The analysis was limited to 11 trial arms, and risk of bias or publication bias metrics are not detailed in the abstract.
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