Anti-hypertensive effects of cinnamon supplementation in adults: A systematic review and dose-response Meta-analysis of randomized controlled trials

Background & Objectives: Despite controversies, no earlier study has systematically summarized findings from earlier studies on the effect of cinnamon supplementation on blood pressure. Therefore, current systematic review and meta-analysis was done on the effect of cinnamon supplementation on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults. Methods: Relevant studies published up to July 2019 were searched through PubMed/Medline, Scopus, ISI Web of Science, Embase and Google Scholar. All randomized clinical trials investigating the impact of oral cinnamon supplementation on any of the blood pressure parameters including SBP or/and DBP were included. Results: Out of 469 citations, 9 trials that enrolled 641 subjects were included. Cinnamon supplementation resulted in significant reduction in SBP (Weighted Mean Differences (WMD): ?6.23?mmHg, 95% CI: ?10.69 to ?1.77, P?=?0.006) and DBP (WMD: ?3.93?mmHg, 95% CI: ?6.33 to ?1.52, P?=?0.001). Greater effects on SBP were detected in trials using ?2?g cinnamon, lasted ?12?weeks and participants aged <50 years? old. DBP was also reduced by using lower doses. However, no significant non-linear associations were found between cinnamon supplementation dosage and study duration with both SBP (For dosage: Pnon-linearity = 0.35, for duration: Pnon-linearity = 0.21) and DBP (For dosage: Pnon-linearity = 0.27, for duration: Pnon-linearity = 0.41). Conclusions: We found a significant reduction in both SBP and DBP following cinnamon supplementation in adults. It could be proposed as a hypotensive supplement in hypertension management.