RESUMO
This meta-analysis and systematic review investigated evidence of the effect of oral micronutrient supplementation on male fertility. Following searches of PubMed, Ovid/Ovid Medline(r) and Embase, 18 randomized, double-blind, placebo-controlled trials were included in the meta-analysis (seven studies) and/or the systematic review (12 studies). The meta-analysis showed significant improvement in semen parameters for selenium (200µg/day and 100µg/day) (standard mean difference [SMD] 0.64 for oligozoospermia, 1.39 for asthenozoospermia), L-carnitine (2 g/day) and acetyl-L-carnitine (LAC; 1 g/day) combined (SMD 0.57 for asthenozoospermia), and co-enzyme Q10 (200 and 300 mg/day) (SMD 0.95 for oligozoospermia, 1.48 for asthenozoospermia, 0.63 for teratozoospermia). The systematic review identified promising data for supplementation with 66 mg/day zinc combined with folic acid (5 mg/day), and the polyunsaturated fatty acids eicosapentaenoic acid (EPA; 1.12 g/day) and docosahexaenoic acid (DHA; 0.72 g/day). Pregnancy rate was evaluated in a limited number of trials (four in the meta-analysis, three in the systematic review). This analysis suggests supplementation with selenium (alone or combined with N-acetylcysteine), co-enzyme Q10 and the combinations L-carnitineâ¯+â¯acetyl-L-carnitine, folic acidâ¯+â¯zinc and EPAâ¯+â¯DHA is beneficial in the treatment of male infertility. Because of the small number of available studies and low number of participants, further well-designed clinical studies are needed to obtain a better overview of efficient methods of treating male infertility.