Evaluation of monotherapy of Coenzyme Q10, L-carnitine or combined therapy on semen parameters in idiopathic male infertility: A placebo-controlled double blind randomized clinical trial.

Plain-language summary

This study tested whether CoQ10, L-carnitine (an amino-acid-like nutrient the body uses to turn fat into energy), or both together improve semen quality in men with low sperm count, poor movement, and abnormal shape. It randomly assigned 200 such men to CoQ10, L-carnitine, both, or a placebo for three months, tracking semen measures, sperm DNA damage, and hormones. Both supplements improved semen quality and sperm DNA health versus placebo, and the combination worked best. Testosterone rose, luteinizing hormone (the pituitary signal that tells the testicles to make testosterone) eased off, and prolactin (a hormone that suppresses testosterone when it runs high) held steady, a pattern that points to the testicles working better rather than to a problem.

Key findings

• CoQ10 and L-carnitine, alone or combined, improved sperm count, movement, and shape in men with unexplained infertility.
• The combination of both supplements worked better than either one alone.
• Testosterone levels rose slightly in the supplement groups, while the placebo group saw no changes.
• Sperm DNA damage (fragmentation) decreased in the supplement groups but not in the placebo group.