The effects of cinnamon supplementation on blood lipid concentrations: A systematic review and meta-analysis

Abstract

Cinnamon is a rich botanical source of polyphenols, whose positive effects on blood lipid concentrations have been hypothesized, but have not been conclusively studied. The objective of the study was to systematically review and evaluate the effect of administration of cinnamon on blood lipid concentrations. We assessed 13 randomized controlled trials with 750 participants investigating the effect of cinnamon supplementation on blood lipid concentrations. A meta-analysis was performed using random effect models, with weighted mean differences (WMDs; with 95% confidence interval [CI]) for endpoints calculated using a random effects model. No statistically significant effect of cinnamon was observed on blood low-density lipoprotein cholesterol (LDL-C; WMD: -0.16mmol/L [-6.19mg/dL], 95% CI: -0.35, 0.03 [-13.53, 1.16], P=.10) and high-density lipoprotein cholesterol (HDL-C; WMD: 0.05mmol/L [1.92mg/dL], 95% CI: -0.03, 0.12 [-0.03, 4.64], P=.21) concentrations. However, a statistically significant reduction in blood triglycerides (WMD: -0.27mmol/L [-23.91mg/dL], 95% CI: -0.39, -0.14 [-34.54, -12.40], P<.01) and total cholesterol concentrations (WMD: -0.36mmol/L [-13.92mg/dL], 95% CI: -0.63, -0.09 [-24.36, -3.48], P<.01) was observed. HDL-C was significantly elevated after the omission of 1 study (WMD: 0.04mmol/L [1.54mg/dL], 95% CI: 0.03, 0.06 [1.16, 2.32], P<.01) during our sensitivity analysis. A meta-regression analysis was conducted, and no significant association was found between changes in lipid parameters and cinnamon dose. In contrast, changes in blood levels of total cholesterol (slope: 0.09; 95% CI: 0.02, 0.16; P<.01), LDL-C (slope: 0.05; 95% CI: 0.001, 0.10; P=.05) and triglycerides (slope: 0.06; 95% CI: 0.04, 0.09; P<.01) were significantly and positively associated with the duration of supplementation. No statistically significant association was found between blood HDL-C changes and duration of supplementation. Cinnamon supplementation significantly reduced blood triglycerides and total cholesterol concentrations without any significant effect on LDL-C and HDL-C.