Does L-carnitine supplementation affect serum levels of enzymes mainly produced by liver? A systematic review and meta-analysis of randomized controlled clinical trials

Farzaneh Pirmadah, Nahid Ramezani-Jolfaie, Mohammad Mohammadi, Nasir Talenezhad, Cain Clark, Amin Salehi-Abargouei

Research output: Contribution to journalReview article

Abstract

Background and aims: l-carnitine supplementation is proposed to reduce liver enzymes levels; however, previous findings were equivocal. The current systematic review and meta-analysis of randomized controlled clinical trials (RCTs) were performed to assess the effect of l-carnitine supplementation on serum levels of enzymes mainly produced by liver [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP)]. Methods: Online databases as well as the reference lists of relevant studies were searched from inception up to June 2019. The risk of bias in individual studies was assessed using Cochrane Collaboration’s tool. Data were pooled using the random-effects model and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Results: In total, 18 RCTs (1161 participants) met the eligibility criteria. l-carnitine supplementation dose ranged from 500 to 4000 mg/day. l-carnitine supplementation significantly reduced serum ALT (MD = − 8.65 IU/L, 95% CI − 13.40, − 3.90), AST (MD = − 8.52 IU/L, 95% CI − 12.16, − 4.89), and GGTP (MD = − 8.80 IU/L, 95% CI − 13.67, − 3.92) levels. The subgroup analysis showed that l-carnitine might be more effective in reducing the enzymes when supplemented in higher doses (≥ 2000 mg/day), for longer durations (> 12 weeks), and among patients with liver diseases. The meta-evidence was graded as “moderate” for ALT and AST, and “low” for GGTP according to NutriGrade scoring system. Conclusion: l-carnitine supplementation significantly improves circulating ALT, AST and GGTP levels; therefore, it might positively affect liver function, especially among patients with liver diseases. Further high-quality RCTs are recommended to confirm our results.

Original languageEnglish
Pages (from-to)(In-press)
Number of pages17
JournalEuropean Journal of Clinical Nutrition
Volume(In-press)
Early online date5 Aug 2019
DOIs
Publication statusE-pub ahead of print - 5 Aug 2019

Fingerprint

Carnitine
Meta-Analysis
Randomized Controlled Trials
gamma-Glutamyltransferase
Aspartate Aminotransferases
Alanine Transaminase
Liver
Enzymes
Serum
Confidence Intervals
Liver Diseases
Databases

Keywords

  • Alanine aminotransferase (ALT)
  • Aspartate aminotransferase (AST)
  • Meta-analysis
  • Systematic review
  • l-carnitine

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Does L-carnitine supplementation affect serum levels of enzymes mainly produced by liver? A systematic review and meta-analysis of randomized controlled clinical trials. / Pirmadah, Farzaneh ; Ramezani-Jolfaie, Nahid ; Mohammadi, Mohammad ; Talenezhad, Nasir ; Clark, Cain; Salehi-Abargouei, Amin .

In: European Journal of Clinical Nutrition, Vol. (In-press), 05.08.2019, p. (In-press).

Research output: Contribution to journalReview article

Pirmadah, Farzaneh ; Ramezani-Jolfaie, Nahid ; Mohammadi, Mohammad ; Talenezhad, Nasir ; Clark, Cain ; Salehi-Abargouei, Amin . / Does L-carnitine supplementation affect serum levels of enzymes mainly produced by liver? A systematic review and meta-analysis of randomized controlled clinical trials. In: European Journal of Clinical Nutrition. 2019 ; Vol. (In-press). pp. (In-press).
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abstract = "Background and aims: l-carnitine supplementation is proposed to reduce liver enzymes levels; however, previous findings were equivocal. The current systematic review and meta-analysis of randomized controlled clinical trials (RCTs) were performed to assess the effect of l-carnitine supplementation on serum levels of enzymes mainly produced by liver [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP)]. Methods: Online databases as well as the reference lists of relevant studies were searched from inception up to June 2019. The risk of bias in individual studies was assessed using Cochrane Collaboration’s tool. Data were pooled using the random-effects model and expressed as mean differences (MDs) with 95{\%} confidence intervals (CIs). Results: In total, 18 RCTs (1161 participants) met the eligibility criteria. l-carnitine supplementation dose ranged from 500 to 4000 mg/day. l-carnitine supplementation significantly reduced serum ALT (MD = − 8.65 IU/L, 95{\%} CI − 13.40, − 3.90), AST (MD = − 8.52 IU/L, 95{\%} CI − 12.16, − 4.89), and GGTP (MD = − 8.80 IU/L, 95{\%} CI − 13.67, − 3.92) levels. The subgroup analysis showed that l-carnitine might be more effective in reducing the enzymes when supplemented in higher doses (≥ 2000 mg/day), for longer durations (> 12 weeks), and among patients with liver diseases. The meta-evidence was graded as “moderate” for ALT and AST, and “low” for GGTP according to NutriGrade scoring system. Conclusion: l-carnitine supplementation significantly improves circulating ALT, AST and GGTP levels; therefore, it might positively affect liver function, especially among patients with liver diseases. Further high-quality RCTs are recommended to confirm our results.",
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AU - Pirmadah, Farzaneh

AU - Ramezani-Jolfaie, Nahid

AU - Mohammadi, Mohammad

AU - Talenezhad, Nasir

AU - Clark, Cain

AU - Salehi-Abargouei, Amin

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N2 - Background and aims: l-carnitine supplementation is proposed to reduce liver enzymes levels; however, previous findings were equivocal. The current systematic review and meta-analysis of randomized controlled clinical trials (RCTs) were performed to assess the effect of l-carnitine supplementation on serum levels of enzymes mainly produced by liver [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP)]. Methods: Online databases as well as the reference lists of relevant studies were searched from inception up to June 2019. The risk of bias in individual studies was assessed using Cochrane Collaboration’s tool. Data were pooled using the random-effects model and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Results: In total, 18 RCTs (1161 participants) met the eligibility criteria. l-carnitine supplementation dose ranged from 500 to 4000 mg/day. l-carnitine supplementation significantly reduced serum ALT (MD = − 8.65 IU/L, 95% CI − 13.40, − 3.90), AST (MD = − 8.52 IU/L, 95% CI − 12.16, − 4.89), and GGTP (MD = − 8.80 IU/L, 95% CI − 13.67, − 3.92) levels. The subgroup analysis showed that l-carnitine might be more effective in reducing the enzymes when supplemented in higher doses (≥ 2000 mg/day), for longer durations (> 12 weeks), and among patients with liver diseases. The meta-evidence was graded as “moderate” for ALT and AST, and “low” for GGTP according to NutriGrade scoring system. Conclusion: l-carnitine supplementation significantly improves circulating ALT, AST and GGTP levels; therefore, it might positively affect liver function, especially among patients with liver diseases. Further high-quality RCTs are recommended to confirm our results.

AB - Background and aims: l-carnitine supplementation is proposed to reduce liver enzymes levels; however, previous findings were equivocal. The current systematic review and meta-analysis of randomized controlled clinical trials (RCTs) were performed to assess the effect of l-carnitine supplementation on serum levels of enzymes mainly produced by liver [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP)]. Methods: Online databases as well as the reference lists of relevant studies were searched from inception up to June 2019. The risk of bias in individual studies was assessed using Cochrane Collaboration’s tool. Data were pooled using the random-effects model and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Results: In total, 18 RCTs (1161 participants) met the eligibility criteria. l-carnitine supplementation dose ranged from 500 to 4000 mg/day. l-carnitine supplementation significantly reduced serum ALT (MD = − 8.65 IU/L, 95% CI − 13.40, − 3.90), AST (MD = − 8.52 IU/L, 95% CI − 12.16, − 4.89), and GGTP (MD = − 8.80 IU/L, 95% CI − 13.67, − 3.92) levels. The subgroup analysis showed that l-carnitine might be more effective in reducing the enzymes when supplemented in higher doses (≥ 2000 mg/day), for longer durations (> 12 weeks), and among patients with liver diseases. The meta-evidence was graded as “moderate” for ALT and AST, and “low” for GGTP according to NutriGrade scoring system. Conclusion: l-carnitine supplementation significantly improves circulating ALT, AST and GGTP levels; therefore, it might positively affect liver function, especially among patients with liver diseases. Further high-quality RCTs are recommended to confirm our results.

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KW - Aspartate aminotransferase (AST)

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KW - Systematic review

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