Table 2.
Effects of L-Carnitine supplementation in men fertility.
| Aims of the Study | Period, Dosing, Route of Administration | Population | Main Results | References |
|---|---|---|---|---|
| Determine the effects of LC on sperm parameters in patients with idiopathic sperm abnormalities | 3 months; 1 g of LC orally; 3 times a day |
48 smokers and 122 non-smokers (Aged 20–56 years) |
Increased sperm motility; Increased normal-shaped spermatozoa. |
Khademi et al., 2005 [99] |
| Explore the clinical effect of LC on infertile males with asthenozoospermia | 3 months; 2 g/day of LC |
135 patients with asthenozoospermia | Increased sperm motility; Raised rate of pregnancy. |
Wang et al., 2010 [40] |
| Determine the efficacy of combined LC and ALC therapy in infertile males with oligoasthenoteratozoospermia | 2 months’ wash out, 6 months’ therapy, 2 month follow-up; 10 mL vial containing 2 g/d carnitine orally administered; 500 mg twice per day orally every 12 h of ALC; |
60 infertile men with oligoasthenoteratozoospermia (Aged 20–40 years) |
Increased sperm motility. | Lenzi et al., 2004 [28] |
| Investigate the effect of supplementation with LC and ALC on sperm quality in 104 subjects with oligo- and/or astheno- and/or teratozoospermia with or without varicocele. | 6 months; two sachets daily of a supplement containing 1000 mg LC, 500 mg ALC, and other micronutrients |
104 men with oligo and/or astheno and/or teratozoospermia with or without varicocele (Aged 18–48 years) |
Increased sperm concentration; Increased total sperm count; Increased total motility. |
Busetto et al., 2018 [102] |
| Evaluate the effect of LC on low sperm acrosin activity in infertile men | 3 months; 1 g of LC |
240 male infertility patients with low sperm acrosin activity | Increased sperm motility; Increased sperm acrosin activity; Increased sperm concentration. |
Sun et al., 2018 [100] |
| Study the effects of complex ALC, LC, fumarate, and alpha-lipoic acid on oxidative stress, ejaculate quality, and sperm DNA fragmentation in men with infertility. | 6 months; 10 g of the supplement once a day |
80 infertile men with increased levels of sperm DNA fragmentation and oxidative stress (Aged 25–40 years) |
Improved sperm mobility and morphology; Decreased free oxygen radicals: Decrease in DNA fragmentation. |
Gamidov et al., 2019 [23] |
| Evaluate a combined treatment with LC and acetyl-L-Carnitine with micronutrients as a treatment for infertility in men | 6 months; 1.0 g LC, 0.5 g ALC and other micronutrients |
175 males with idiopathic oligoasthenozoospermia (Aged 19–44 years) |
Decreased DNA fragmentation; Increased seminal carnitine concentration; Improved sperm motility. |
Micic et al., 2018 [107] |
| Comparing sperm parameters and hormonal levels with LC vs. CoQ10 and vitamin E therapy for patients with asthenozoospermia and teratozoospermia. | 3 months; 15 g/bag LC complex; orally, one bag at a time, twice a day |
143 patients with asthenozoospermia and teratozoospermia. | Increased sperm motility, morphology, and concentration; Improved testosterone levels; Superior to the others in improving sperm quality. |
Ma et al., 2020 [39] |
| Study the influence of a multi-component nutrient dietary supplement on sperm parameters and pregnancy rates in idiopathic male infertility | 6 months; supplement containing LC/ALC, l-arginine, glutathione, co-enzyme Q10, zinc, vitamin B9, vitamin B12, selenium, once daily |
83 males aged 21–50 years with oligo-, astheno-, and teratozoospermia (Aged 21–50 years) |
Improved sperm quality (concentration, motility, and morphology); Increased fertility rates. |
Kopets et al., 2020 [41] |
| Assess the effect of LC and CoQ10 during, before, and after freezing in oligospermia men | 1 h to 2 weeks; G1—LC (100 µM) for 1 h; G3—CoQ10 (100 µM) for 1 h; G4—LC and CoQ10 (100 µM) for 1 h; G5—freezing control group; G6—frozen with CoQ10 (100 µM); G7—frozen with LC (100 µM); G8—frozen with 100 µM (LC + CoQ10) for 2 weeks. |
30 oligospermic men (Aged 25–40 years) |
Decreased ROS levels; Improved motility and protamine deficiency. |
Nezhad et al., 2021 [101] |
Abbreviations: LC—L-Carnitine; ALC—acetyl-L-Carnitine; CoQ10—Coenzyme Q10.