Impact of Cinnamon Supplementation on Cardiometabolic Biomarkers of Inflammation and Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

Background & objective: To date, cinnamon supplementation has been investigated due to its antioxidant and anti-inflammatory properties. Several studies have confirmed the effects of cinnamon supplementation on several markers of cardiometabolic health. However, the effects of cinnamon supplementation on inflammation and oxidative stress levels warrant further investigation. Hence, the current meta-analysis was conducted to elucidate the impact of cinnamon supplementation on biomarkers of inflammation and oxidative stress. Methods: To perform this systematic review and meta-analysis, we employed the Preferred Reporting Items of Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The systematic search of available clinical trials was performed using the following databases: PubMed/MEDLINE, Scopus, Cochrane Library, Web of Science, Embase, and Google Scholar, up to January 2020. Results: After removing the duplicates, 1145 studies were eligible for analysis and 12 of them were included in the meta-analysis. The dose of cinnamon powder investigated in the included trials ranged from 1.5 to 4 g/day. Cinnamon supplementation resulted in a significant reduction of C-reactive protein (CRP) (weight mean difference (WMD): -2.22 mg/L, 95 % CI: -3.74, -0.69, P = 0.004) and malondialdehyde (MDA) (WMD: -0.79 mmol/L, 95 % CI: -1.28, -0.29, P = 0.002), and marginally statistical significant decrease in interleukin-6 (IL-6) (WMD: -1.48 pg/mL, 95 % CI: -2.96, -0.01, P = 0.049). Moreover, it was associated with an increase in the total antioxidant capacity (TAC) (WMD: 0.34 mmol/L, 95 % CI: 0.04, 0.64, P = 0.026). However, the levels of intercellular adhesion molecule-1 (ICAM-1) (WMD: 1.53 ng/mL, 95 % CI: -12.03, 15.10, P = 0.82) did not change significantly following cinnamon supplementation. Conclusions: Cinnamon supplementation may be an adjuvant for reducing inflammation and oxidative stress levels in humans.