The Effect of the L-Carnitine Supplementation on Obesity Indices: An Umbrella Meta-Analysis

Obesity, one of the most frequent health risks, represents a global public health problem. The potential impact of L-carnitine, a vital nutrient for energy metabolism, on weight loss is worth considering. However, given the inconclusive results from recent meta-analyses on L-carnitine, we conducted an umbrella meta-analysis of placebo-controlled and controlled trials to evaluate the effect of L-carnitine on anthropometric indices.

Data synthesis: A comprehensive search approach using the relevant keywords was performed in PubMed, Web of Science, Scopus databases, and Google Scholar up to March 2023. Meta-analyses published in English that provided quantitative statistical analyses regarding the effects of L-carnitine on body weight, waist circumference (WC), and body mass index (BMI) were included. A random-effects model and subgroup analysis were performed based on the L-carnitine dosage and study population.

A total of 16,352 participants were included. Intervention durations ranged from 8 to 30 weeks, with L-carnitine dosages ranging between 150 and 4000 mg/day. The pooled results of the eight included meta-analyses indicated that L-carnitine supplementation can significantly decrease weight (effect size (ES) = -1.11; 95% confidence intervals (CIs): -1.90, -0.33, p = 0.005; I² = 90.6%, p < 0.001), BMI (ES = -0.33; 95% CI: -0.61, -0.04, p = 0.026; I² = 89.8%, p < 0.001), and WC (ES = -1.34; 95% CI: -1.83, -0.85, p < 0.001; I² = 00.0%, p = 0.442).

The findings of this umbrella meta-analysis support that supplementation of L-carnitine supplementation can successfully manage weight, BMI, and WC reduction. Therefore, L-carnitine might help treat obesity. PROSPERO Registration Number: CRD42022307951.