Introduction: Hypertension is a chronic condition that might lead to renal and cardiovascular diseases. The previous trials examining the effect of cinnamon supplementation on blood pressure have led to conflicting results. The present systematic review aimed to summarize the effect of cinnamon supplementation on blood pressure using a meta-analysis of published randomized controlled clinical trials.
Methods: To identify the eligible articles, MEDLINE, SCOPUS, ISI Web of Science, and Google Scholar were searched from inception until September 2019 for relevant articles. The risk of bias assessment was performed using the Cochrane collaboration tool. A Random-effects model was applied to calculate the summary effects.
Results: Totally, 11 trials with 686 participants were included in this systematic review and meta-analysis. The dose of cinnamon supplement consumption varied from 500 to 10000 mg/d. The meta-analysis revealed that cinnamon supplementation significantly decreases systolic blood pressure (SBP) [WMD (weighted mean difference)= -5.72 mmHg, 95% confidence interval (CI): -8.63 to -2.80; P<0.001, I2= 81.1)] and diastolic blood pressure (DBP) (WMD= -4.06 mmHg, 95% CI: -6.68 to -1.44; P= 0.002, I2 = 88.6). Subgroup analysis suggested no significant reduction of DBP in subjects with diabetes (WMD= -2.015 mmHg, 95% CI: -4.55 to 0.52; P= 0.12, I2 = 72.3) and prediabetes or metabolic syndrome (WMD= -4.8 mmHg, 95% CI: -10.06 to 0.44; P= 0.073, I2= 92.5).
Conclusions: Cinnamon supplementation could be beneficial in lowering SBP and DBP in adults. Further studies with different doses are recommended to confirm the present findings.
Systematic review/Meta-analysis Efficacy and tolerability of renzapride in irritable bowel syndrome: a meta-analysis of randomized, controlled clinical trials including 2528 patients
