The effect of ginger supplementation on lipid profile: A systematic review and meta-analysis of clinical trials

Background: Elevated levels of blood lipids are a major cause of atherosclerosis and consequently cardiovascular disease. Several studies used ginger as a lipid lowering agent. Purpose: The aim of the present systematic review and meta-analysis was to clarify the effect of ginger supplementation on lipid parameters. Methods: PubMed, Scopus, Science Direct, ISI Web of Science and Google Scholar were systematically searched until May 2017 to find clinical trials which examined effect of ginger supplementation on level of lipid parameters in adult participants. Means for blood lipids and potential sources of heterogeneity were extracted. A subgroup analysis was applied to find out potential sources of inter-study heterogeneity. Results: A total of 12 trials (586 participants) were included in the meta-analysis. Pooled analysis suggested that ginger supplementation reduced triacylglycerol (TAG) (-17.59 mg/dl; 95% CI: - 29.32 to - 5.87) and low density lipoprotein cholesterol (LDL-C) (- 4.90 mg/dl; 95% CI: -22.30 to - 6.17). Ginger had no significant effect on total cholesterol (TC) (- 5.13 mg/dl, 95% CI: -11.05 to 0.78; P = 0.089) and high density lipoprotein cholesterol (HDL-C) (2.18 mg/dl, 95% CI: -0.08 to 4.45; P = 0.059). As inter-study heterogeneity was high, studies were classified by ginger dosage. Stratified analysis showed a significant reduction in TC (-12.26 mg/dl; 95% CI: - 22.37 to - 2.16) and TAG ( - 38.42 mg/dl; 95% CI: - 57.01 to -19.82) in studies which used <= 2 g/ day of ginger. However, a similar significant effect was not observed in trials with > 2 g/day of ginger. Neither studies which used <= 2 g/day nor trials which used > 2 g/day of ginger showed significant changes in LDL-C or HDL-C. Conclusion: The present systematic review and meta-analysis suggests that ginger had a favorable effect on TAG and LDL-C. Also, the result revealed that low dose of ginger (<= 2 g/day) had greater lowering impact on TAG and TC. Further studies with large-scale and better design are needed to confirm this result.