Effects of L-carnitine supplementation on glucolipid metabolism: a systematic review and meta-analysis.

2023
Food & function 14(5)
- Yanfei Li
- Yuchen Xie
- Chensheng Qiu
- Bowen Yu
- Fangzheng Yang
- Yuanchao Cheng
- Weizhen Zhong
- Junhua Yuan

PubMed: 36815696
DOI: 10.1039/d2fo02930h

Study Design

Type: Meta-Analysis
Population: adults
Methods: Meta-analysis in a random effect model with heterogeneity determined by I2, and subgroup analyses

Rigorous Journal

Background: L-carnitine supplementation has been utilized against glucolipid metabolism disruption. However, to the best of our knowledge, no meta-analysis process has analyzed the effects of L-carnitine supplementation on insulin resistance, fasting blood glucose, lipid metabolism, and liver enzyme levels in adults. Methods: Through the analysis and screening of 12 221 studies, 15 studies were selected from eligible trials for meta-analysis. Meta-analysis was performed in a random effect model with heterogeneity determined by I², and subgroup analyses were used to further identify the source of heterogeneity. Result: The results showed significant effects of L-carnitine on FBG (MD = -4.94 mg dL^-1, 95% CI: -7.07 to -2.82), insulin (MD = -0.99 μU mL^-1, 95% CI: -1.41 to -0.56), HOMA-IR (MD = -0.58, 95% CI: -0.77 to -0.38), TG (MD = -11.22 mg dL^-1, 95% CI: -19.21 to -3.22), TC (MD = -6.45 mg dL^-1, 95% CI: -9.95 to -2.95, LDLc (MD = -8.28 mg dL^-1, 95% CI: -11.08 to -5.47), and ALT (MD = -19.71 IU L^-1, 95% CI: -36.45 to -2.96). However, no significant effect of L-carnitine supplementation was observed in HDLc (MD = -0.77 mg dL^-1, 95% CI: -0.10 to -1.63) or AST (MD = -11.05 IU L^-1, 95% CI: -23.08 to 0.99). The duration of carnitine supplementation was negatively associated with mean differences in FBG, as assessed by meta-regression. Conclusion: The current meta-analysis revealed that L-carnitine may have favorable effects on glucolipid profile, especially insulin, FBG, HOMA-IR, TG, TC, LDLc, and ALT levels.

Research Insights

L-Carnitine→Improved Insulin Levels
significant effects of L-carnitine on ... insulin (MD = -0.99 μU mL-1, 95% CI: -1.41 to -0.56)
Effect
Beneficial
Effect size
Small
L-Carnitine→Reduced Alanine Aminotransferase Level
significant effects of L-carnitine on ... ALT (MD = -19.71 IU L-1, 95% CI: -36.45 to -2.96)
Effect
Beneficial
Effect size
Small
L-Carnitine→Reduced Aspartate Aminotransferase Levels
no significant effect of L-carnitine supplementation was observed in ... AST (MD = -11.05 IU L-1, 95% CI: -23.08 to 0.99)
Effect
Neutral
Effect size
Small
L-Carnitine→Reduced Fasting Blood Glucose Levels
significant effects of L-carnitine on FBG (MD = -4.94 mg dL-1, 95% CI: -7.07 to -2.82)
Effect
Beneficial
Effect size
Small
L-Carnitine→Reduced HDL Cholesterol Level
no significant effect of L-carnitine supplementation was observed in HDLc (MD = -0.77 mg dL-1, 95% CI: -0.10 to -1.63)
Effect
Neutral
Effect size
Small
L-Carnitine→Reduced HOMA-IR
significant effects of L-carnitine on ... HOMA-IR (MD = -0.58, 95% CI: -0.77 to -0.38)
Effect
Beneficial
Effect size
Small
L-Carnitine→Reduced Low-Density Lipoprotein Level
significant effects of L-carnitine on ... LDLc (MD = -8.28 mg dL-1, 95% CI: -11.08 to -5.47)
Effect
Beneficial
Effect size
Small
L-Carnitine→Reduced Total Cholesterol Levels
significant effects of L-carnitine on ... TC (MD = -6.45 mg dL-1, 95% CI: -9.95 to -2.95)
Effect
Beneficial
Effect size
Small
L-Carnitine→Reduced Triglyceride Levels
significant effects of L-carnitine on ... TG (MD = -11.22 mg dL-1, 95% CI: -19.21 to -3.22)
Effect
Beneficial
Effect size
Small