Effects of cinnamon supplementation on systolic and diastolic blood pressure: a systematic review and meta-analysis of randomized controlled clinical trials

ABSTRACT Background: Hypertension is a chronic condition that might lead to renal and cardiovascular diseases. Previous clinical trials examining the effect of cinnamon supplementation on blood pressure have led to conflicting results. The present study 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’s tool. A Random-effects model was applied to calculate the summary effects. Results: Totally, 11trials 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 in 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.