In this placebo-controlled study of 60 infertile men, giving L-carnitine (LC) and Acetyl-L-Carnitine (ALC) increased sperm motility and improves the total free radical scavenging capacity in semen. The study design was 1 month of run in, 6 months of therapy or placebo, and 3 months of follow-up evaluation. The participants were randomized to a double-blind therapy of LC 3 g/day, ALC 3 g/day, a combination of LC 2 g/day and ALC 1 g/day, or placebo. Results showed that total sperm cell motility and forward sperm cell motility increased in subjects who received ALC alone, or in combination with LC after 3 months. Those with the worst sperm motility had the best response.
I recommend Acetyl-L-Carnitine 1,000 mg/day plus Carnitine 1,000 mg/day.
“Placebo-controlled double-blind randomized trial on the use of L-carnitine, L-acetylcarnitine, or combined L-carnitine and L-acetylcarnitine in men with idiopathic asthenozoospermia,” Balercia G, Regoli F, et al, Fertil Steril., 2005; 84(3): 662-71.