A systematic review and meta-analysis of randomized controlled trials investigating the effects of curcumin on blood lipid levels

Curcumin is a polyphenolic natural compound with diverse and attractive biological activities. There has been in-vitro, preclinical and clinical evidence on the cardioprotective and lipid-lowering effects of curcumin. The present review aimed to systematically review and meta-analyze current clinical evidence on the effects of curcumin supplementation on blood lipids.A comprehensive literature search in Medline, Scopus, AMED, Cochrane and clinical trial registry databases was performed to identify randomized controlled trials investigating the effect of curcumin on any component of serum lipid profile including total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides. Meta-analysis of eligible studies was conducted using a random-effects approach.Five studies comprising 10 treatment arms (n = 133 in the curcumin and 90 in the control group) fulfilled the inclusion criteria. Meta-analysis of findings did not indicate a significant effect of curcumin on any of the lipid parameters. The estimated pooled mean changes (95% confidence interval) following curcumin supplementation were 8.97 (95% CI: −4.56 to 22.51) mg/dL (for total cholesterol; p = 0.19); 16.15 (−4.43 to 36.74) mg/dL (for LDL-C; p = 0.12); −0.59 (−1.66 to 0.49) mg/dL (for HDL-C; p = 0.28) and −1.29 (−9.05 to 6.48) mg/dL (for triglycerides; p = 0.75). In the same manner, subgroup analysis of studies on patients at cardiovascular risk did not indicate any significant effect of curcumin on circulating lipid levels. There was a significant heterogeneity for the impact of curcumin on total cholesterol, LDL-C and triglycerides but not HDL-C.In light of the present meta-analysis, curcumin supplementation has apparently no effect on serum total cholesterol, LDL-C, triglycerides and HDL-C levels when considering heterogeneous populations. However, further randomized controlled trials with longer supplementation duration, and bioavailability-improved formulations of curcumin are warranted to be conducted in dyslipidemic subjects for a more robust assessment of the lipid-modulating properties of this phytochemical.