LAUSR

BACKGROUND The findings of trials investigating the effects of carnitine administration on serum lipids are inconsistent. This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the existing evidence and find which the effects of carnitine supplementation on serum lipids are. Methods: Two authors independently searched electronic databases including MEDLINE, EMBASE, Cochrane Library, and Web of Science from inception until February 2019, in order to find relevant RCTs. The quality of selected RCTs was evaluated using the Cochrane Collaboration risk of bias tool. Cochrane's Q test and I-square (I2) statistic were used to determine the heterogeneity across included trials. Weight mean difference (SMD) and 95% CI between two intervention groups were used to determine pooled effect sizes. Results: Out of 686 potential papers selected based on keywords, 43 studies met the inclusion criteria and were eligible for the meta-analysis. The pooled results indicated that L-carnitine administration led to a significant decrease in triglycerides (WMD: -4.08; 95% CI: -7.59, -0.58), total cholesterol (WMD: -7.75; 95% CI: -11.23, -4.28) and LDL-cholesterol concentrations (WMD: -4.67; 95% CI: -7.03, -2.30), and a significant increase in HDL-cholesterol levels (WMD: 1.01; 95% CI: 0.28, 1.74). L-carnitine supplementation did not influence VLDL-cholesterol concentrations. Conclusions: This meta-analysis demonstrated that carnitine administration significantly reduced triglycerides, total cholesterol and LDL-cholesterol levels, and significantly increased HDL-cholesterol levels, but did not affect VLDL-cholesterol levels.