Efficacy of L-carnitine supplementation for management of blood lipids: A systematic review and dose-response meta-analysis of randomized controlled trials

Abstract

Background and aim: L-carnitine has an important role in fatty acid metabolism and could therefore act as an adjuvant agent in the improvement of dyslipidemia. The purpose of present systematic review and meta-analysis was to critically assess the efficacy of L-carnitine supplementation on lipid profiles. Methods and results: We performed a systematic search of all available randomized controlled trials (RCTs) in the following databases: Scopus, PubMed, ISI Web of Science, The Cochrane Library. Mean difference (MD) of any effect was calculated using a random-effects model. In total, there were 55 eligible RCTs included with 58 arms, and meta-analysis revealed that L-carnitine supplementation significantly reduced total cholesterol (TC) (56 arms-MD: -8.53 mg/ dl, 95 CI: -13.46, -3.6, I-2: 93), low-density lipoprotein-cholesterol (LDL-C) (47 arms-MD: -5.48 mg/dl, 95 CI: -8.49, -2.47, I2: 94.5) and triglyceride (TG) (56 arms-MD: -9.44 mg/dl, 95 CI: -16.02, -2.87, I-2: 91.8). It also increased high density lipoprotein-cholesterol (HDL-C) (51 arms-MD:1.64 mg/dl, 95 CI:0.54, 2.75, I-2: 92.2). L-carnitine supplementation reduced TC in non-linear fashion based on dosage (r = 21.11). Meta-regression analysis indicated a linear relationship between dose of L-carnitine and absolute change in TC (p = 0.029) and LDL-C (p = 0.013). Subgroup analyses showed that L-carnitine supplementation did not change TC, LDL-C and TG in patients under hemodialysis treatment. Intravenous L-carnitine and lower doses (>2 g/day) had no effect on TC, LDL-C and triglycerides. Conclusion: L-carnitine supplementation at doses above 2 g/d has favorable effects on patients' lipid profiles, but is modulated on participant health and route of administration. (C) 2019 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.