Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension: 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 25875025 · doi:10.1097/HJH.0000000000000585
What was done
The authors searched PubMed, Cochrane Library, Scopus, and EMBASE through July 2014 to identify randomized controlled trials evaluating the effect of Hibiscus sabdariffa (sour tea) supplementation on systolic blood pressure (SBP) and diastolic blood pressure (DBP). Study selection and data extraction were conducted by two independent reviewers. Quantitative data synthesis and meta-regression were performed using a fixed-effect model, alongside leave-one-out sensitivity analysis. Five RCTs comprising seven treatment arms and 390 total participants (225 in H. sabdariffa groups, 165 in control groups) were included.
What was found
Hibiscus sabdariffa supplementation significantly reduced both SBP (weighted mean difference -7.58 mmHg, 95% CI -9.69 to -5.46, P < 0.00001) and DBP (weighted mean difference -3.53 mmHg, 95% CI -5.16 to -1.89, P < 0.0001). Meta-regression indicated that blood pressure reductions were inversely associated with baseline blood pressure values. Findings were reported as robust in sensitivity analyses.
Why it matters
This meta-analysis quantifies the blood pressure-lowering effect of sour tea across existing trials, providing pooled clinical evidence that H. sabdariffa can produce modest but statistically significant reductions in both systolic and diastolic blood pressure.
Limits
The total sample size is small (5 RCTs, 390 participants). The abstract does not report details on treatment duration, dosage, extract standardization, participant baseline health characteristics, control types (placebo versus active comparators), or adverse events.
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