Curcumin Preparations Can Improve Flow-Mediated Dilation and Endothelial Function: A Meta-Analysis

Introduction: Endothelial dysfunction is an early marker of atherosclerosis. Flow-mediated dilation (FMD), measured by ultrasonography, is used to noninvasively assess endothelial dysfunction. Preparations of curcumin, a naturally occurring pigment found in turmeric, may improve FMD and thus endothelial dysfunction. We did a systematic review and meta-analysis to analyze the effect of curcumin preparations on endothelial dysfunction. Methods: Five randomized clinical trials met the inclusion criteria for meta-analysis. The primary outcome was an improvement in FMD, as measured at brachial artery, after supplementations with curcumin preparations compared to the control group. Standardized mean difference and Hedges’ g were used for effect size (ES) measurement. An ES of 0.2–0.5 is considered small, 0.5–0.8 is medium, and more than 0.8 is large. Publication bias was studied too. Results: We found supplementation with curcumin preparations had an overall ES (standard difference in means) of 1.379 (95% CI 0.485–2.274, p = 0.003) on FMD. The overall Hedges’ g was 1.353 (95% CI 0.47–2.235, p = 0.03). This analysis suggests a positive and large ES of curcumin preparations on FMD using a random effect model. Smokers had a smaller increase in FMD compared to nonsmokers (ES 0.379 vs. 1.639, p = 0.034). Conclusion: This meta-analysis of 5 randomized clinical trials indicates a significant effect of curcumin preparations to increase the FMD compared to placebo and thus endothelial function. This effect is not strongly noticed in smokers.