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

  • 2025-04-28
  • International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition 95(2)
    • Fatemeh Hamedi-Kalajahi
    • Meysam Zarezadeh
    • Mahsa Malekahmadi
    • Parsa Jamilian
    • Parmida Jamilian
    • Roghayeh Molani-Gol
    • Alireza Ostadrahimi

Study Design

Type
Meta-Analysis
Sample size
n = 352
Population
16,352 participants
Methods
umbrella meta-analysis of placebo-controlled and controlled trials; comprehensive search in PubMed, Web of Science, Scopus, and Google Scholar up to March 2023; random-effects model and subgroup analysis based on L-carnitine dosage and study population
Duration
8 to 30 weeks
Funding
Unclear

Aims

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.

Methods

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.

Results

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).

Conclusion

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.

Research Insights

  • L-Carnitine→Reduced Body Mass Index

    BMI (ES = -0.33; 95% CI: -0.61, -0.04, p = 0.026; I² = 89.8%, p < 0.001)

    Effect
    Beneficial
    Effect size
    Small
    Dose
    150 to 4000 mg/day
  • L-Carnitine→Reduced Body Weight

    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)

    Effect
    Beneficial
    Effect size
    Large
    Dose
    150 to 4000 mg/day
  • L-Carnitine→Reduced Waist Circumference

    WC (ES = -1.34; 95% CI: -1.83, -0.85, p < 0.001; I² = 00.0%, p = 0.442)

    Effect
    Beneficial
    Effect size
    Moderate
    Dose
    150 to 4000 mg/day
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