This study investigated the effects of the administration of ubiquinol (a reduced form of coenzyme Q10) on semen parameters and seminal plasma antioxidant capacity in infertile men with idiopathic oligoasthenoteratozoospermia. A total of 228 men with unexplained infertility were randomly assigned into 2 groups. Group 1 received 200 mg ubiquinol daily orally for 26 weeks and group 2 received placebo. After completion of the 26-week treatment phase, all participants were followed for another 12-week off-drug period. Primary outcomes were improvement in sperm density, sperm motility and sperm strict morphology. At the end of the 26-week treatment period sperm density, sperm motility and sperm morphology were significantly improved compared to placebo. During the treatment period serum follicle-stimulating hormone levels decreased significantly and serum inhibin B concentrations increased significantly. During the off-drug period semen parameters gradually returned to baseline values but the differences were still significant for sperm density and sperm motility. The authors conclude "Ubiquinol was significantly effective in men with unexplained oligoasthenoteratozoospermia for improving sperm density, sperm motility and sperm morphology".
Safarinejad MR, Safarinejad S, Shafiei N, Safarinejad S. Effects of the reduced form of coenzyme q(10) (ubiquinol) on semen parameters in men with idiopathic infertility: a double-blind, placebo controlled, randomized study. J Urol. 2012 Aug;188(2):526-31.