Submitted to: Journal of Andrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2009
Publication Date: 9/5/2009
Citation: Hawkes, W.C., Alkan, Z., Wong, K. 2009. Selenium Supplementation Does Not Affect Testicular Selenium Status or Semen Quality in North American Men. Journal of Andrology. 30:525-533.
Interpretive Summary: We published a study in 2001 that found that consumption of high-selenium foods was associated with decreased sperm motility in eleven healthy men. This study raised coincerns that men taking selenium supplements for cancer prevention might suffer decreased fertility as a side effect. We conducted a follow-up study of high-selenium yeast supplements in 42 healthy free-living men to test for adverse effects on semen quality. Subjects were administered 300 micrograms of selenium per day or a placebo yeast tablet for 48 weeks and subjects were followed for an additional 48 weeks after supplementation. Semen quality was measured with a computer-assisted semen analyzer. We found that selenium had no effect on sperm motility or any other semen quality patrameter associated with fertility. This suggests that healthy men should not be concerned about impairing their fertility by taking over-the-counter selenium supplements.
Technical Abstract: Although selenium (Se) is essential for sperm function experimental animals, high Se intake in humans has been associated with both improvements and impairments in semen quality. We previously reported a decrease in sperm motility in five men fed high-Se foods in a metabolic research unit, but could not rule out other environmental and dietary factors. To follow up these observations, we conducted a randomized, placebo-controlled trial of Se supplementation in 42 free-living men. Subjects were administered 300 'g Se/d as high-Se Baker’s yeast, or low-Se placebo yeast for 48 weeks. Semen analysis was performed four time during the three-week run-in period and then twice a week at 6, 12, 24, 36, 48, 72 and 96 weeks. Blood samples were collected three times during the run-in period and once at each subsequent visit. Se concentration increased 50% in blood plasma and 40% in seminal plasma. Se supplementation did not affect serum androgen concentrations, sperm Se concentration or sperm count, motility, progressive velocity, or morphology. However, serum LH, semen volume and sperm Se decreased in both groups throughout the supplementation and follow-up periods. At the same time, sperm straight line velocity and percent normal morphology increased in both groups. Even though the subject’s dietary Se intake was tripled and their total body Se was doubled by 48 weeks of supplementation, their testicular Se stores were unaffected. These results are consistent with animal studies showing the Se status of testes to be remarkably refractory to dietary Se intake.