Efficacy of selenium and/or N-acetyl-cysteine for improving semen parameters in infertile men: a double-blind, placebo controlled, randomized study

J Urol. 2009 Feb;181(2):741-51. doi: 10.1016/j.juro.2008.10.015. Epub 2008 Dec 16.


Purpose: We explored the efficacy of selenium and/or or N-acetyl-cysteine for improving semen parameters in infertile men, and the associations among semen quality and the concentrations of selenium and N-acetyl-cysteine in seminal plasma.

Materials and methods: The study included 468 infertile men with idiopathic oligo-asthenoteratospermia who were randomized to receive 200 microg selenium orally daily (selenium group of 116), 600 mg N-acetyl-cysteine orally daily (N-acetyl-cysteine group of 118), 200 microg selenium plus 600 mg N-acetyl-cysteine orally daily (selenium plus N-acetyl-cysteine group of 116) or similar regimen of placebo (control group of 118) for 26 weeks, followed by a 30-week treatment-free period. These patients provided blood samples for the measurement of serum testosterone, estradiol, follicle-stimulating hormone, luteinizing hormone, prolactin, inhibin B, selenium and N-acetyl-cysteine. Semen samples were also obtained for routine semen analysis, and the measurement of seminal plasma selenium and N-acetyl-cysteine.

Results: In response to selenium and N-acetyl-cysteine treatment serum follicle-stimulating hormone decreased but serum testosterone and inhibin B increased. All semen parameters significantly improved with selenium and N-acetyl-cysteine treatment. Administering selenium plus N-acetyl-cysteine resulted in additive beneficial effects. A significant positive correlation existed between the seminal plasma concentrations of selenium and N-acetyl-cysteine, and semen parameters. A strong correlation was observed between the sum of the selenium and N-acetyl-cysteine concentrations, and mean sperm concentration (r = 0.67, p = 0.01), sperm motility (r = 0.64, p = 0.01) and percent normal morphology (r = 0.66, p = 0.01).

Conclusions: These results indicate that supplemental selenium and N-acetyl-cysteine improve semen quality. We advocate their use for male infertility treatment.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Acetylcysteine / administration & dosage*
  • Administration, Oral
  • Adult
  • Analysis of Variance
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Drug Administration Schedule
  • Drug Therapy, Combination
  • Follow-Up Studies
  • Humans
  • Infertility, Male / blood*
  • Infertility, Male / diagnosis
  • Infertility, Male / drug therapy*
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Prospective Studies
  • Reference Values
  • Risk Assessment
  • Selenium / administration & dosage*
  • Semen Analysis
  • Sperm Count
  • Sperm Motility / drug effects
  • Statistics, Nonparametric
  • Treatment Outcome


  • Selenium
  • Acetylcysteine