Introduction
- Around 50% of infertility cases in childless couples are due to male factors, and about 44% of infertile men have idiopathic infertility, characterised by unclear pathogenesis and no evidence-based treatment.
- LC supports sperm energy metabolism and motility, with higher LC and LAC levels linked to improved sperm function.
- NAC acts as a potent antioxidant, improving sperm motility and concentration, enhancing the acrosome reaction and reducing ROS and DNA oxidation.
Objective
To assess the effectiveness of LC/LAC and NAC in improving sperm parameters in men with idiopathic asthenozoospermia.
Study details
A meta-analysis was conducted in accordance with the PRISMA guidelines.
Inclusion criteria
- Men with idiopathic male infertility treated with LC/LAC or NAC
Total studies analysed
- Seven randomised controlled trials with 621 patients
Results
LC/LAC vs. placebo
- Sperm motility
9.48% (p = 0.03)
- Normal morphology
4.89% (p = 0.006)
- Sperm concentration
11.17 million/mL (p = 0.25)
- Ejaculated volume
0.13 mL (p = 0.25)
NAC vs. placebo
- Sperm motility
4.69% (p < 0.0001)
- Normal morphology
1.68% (p = 0.0002)
- Sperm concentration
3.8 million/mL (p < 0.00001)
- Ejaculated volume
0.69 mL (p = 0.002)
Sperm motility
- LC/LAC did not show a significant effect on sperm concentration (Figure 1).
Figure 1. Forest plot showing results for the sperm motility.
LAC: L-acetyl-carnitine; LC: L-carnitine; SD: Standard deviation; IV: Inverse variance; CI: Confidence interval; df: Degrees of freedom.
Normal morphology
- Both supplements led to significant improvements in sperm morphology (Figure 2).
Figure 2. Forest plot showing results for the normal morphology.
LAC: L-acetyl-carnitine; LC: L-carnitine; SD: Standard deviation; IV: Inverse variance; CI: Confidence interval; df: Degrees of freedom.
Sperm concentration and ejaculate volume
- NAC showed a significant increase in sperm concentration and ejaculate volume (Figure 3).
- LC/LAC did not show significant effects on sperm concentration.
Figure 3. Forest plot showing results for the ejaculate volume.
LAC: L-acetyl-carnitine; LC: L-carnitine; SD: Standard deviation; IV: Inverse variance; CI: Confidence interval; df: Degrees of freedom.
NAC on serum hormones
- No significant difference was observed in the levels of testosterone, luteinising hormone, follicle-stimulating hormone and prolactin.
Conclusion
Both NAC and LC/LAC significantly improved sperm motility and morphology. NAC, in particular, showed a notable effect on sperm concentration and ejaculate volume, without effecting serum hormone levels.
Abbreviations
LAC: L-acetyl-carnitine; LC: L-carnitine; NAC: N-acetyl-cysteine; PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses
