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Effects of l-carnitine supplementation on weight loss and body composition: A systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis
Nasir Talenezhad et al. Clin Nutr ESPEN. 2020 Jun.
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Abstract

Background and aim: Clinical evidence which investigated the effects of l-carnitine, a vitamin-like substance, on weight loss had led to inconsistent results. This study therefore aimed to examine the effect of l-carnitine supplementation on body weight and composition by including the maximum number of randomized controlled trials (RCTs) and to conduct a dose-response analysis, for the first time.

Methods and results: Online databases were searched up to January 2019. In total, 37 RCTs (with 2292 participants) were eligible. Meta-analysis showed that l-carnitine supplementation significantly decreased body weight [Weighted mean difference (WMD) = -1.21 kg, 95% confidence interval (CI): -1.73, -0.68; P < 0.001], body mass index (BMI) (WMD = -0.24 kg/m2, 95% CI: -0.37, -0.10; P = 0.001), and fat mass (WMD = -2.08 kg, 95% CI: -3.44, -0.72; P = 0.003). No significant effect was seen for waist circumference (WC) and body fat percent. The meta-analysis of high-quality RCTs only confirmed the effect on body weight. A non-linear dose-response association was seen between l-carnitine supplementation and body weight reduction (P < 0.001) suggesting that ingestion of 2000 mg l-carnitine per day provides the maximum effect in adults. This association was not seen for BMI, WC and body fat percent.

Conclusions: l-carnitine supplementation provides a modest reducing effect on body weight, BMI and fat mass, especially among adults with overweight/obesity.

Keywords: Body composition; Body mass index; Body weight; L-carnitine; Meta-analysis; Systematic review.

Copyright © 2020 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no conflict of interest.