What is Selenium?

Selenium (l-Selenomethionine) is a trace mineral essential to the normal function of the human body. It is a crucial antioxidant that prevents free-radical damage, working synergistically with Vitamin E to preserve tissue elasticity. Selenium is also essential in healthy immune system function and its introduction into the diet can reduce the incidents of viral hepatitis in selenium-deficient populations by enhancing immune function.  Even in a non-deficient population of elderly people, Selenium supplementation has been found to stimulate the activity of white blood cells, a primary component of the immune system.  Selenium is also needed to activate thyroid hormones. In addition, this invaluable mineral activates an antioxidant enzyme called Glutathione Peroxidase, which is believed to help protect the body from some forms of cancer. 

How does it work?

Selenium is needed for production of testosterone.  When Selenium levels are low, sperm are immobile because the tail is weakened or deformed.  In men, Selenium is essential for sperm production; almost half of the male body’s supply of Selenium is concentrated in the testicles and seminal ducts adjacent to the prostate gland.

Where does it come from?

Brazil nuts are the best source of Selenium.  Yeast, whole grains and seafood are also good sources.

Safety / Side Effects

Selenium is safe at the level people typically ingest (100-200mcg); however, taking more than 900 mcg of Selenium per day has been reported to cause adverse effects in some people.

Studies Involving Sperm

In order to verify the hypothesis that Selenium (Se) and Vitamin E (Vit E) could improve male fertility, nine oligaoasthnoteratozoospermic men were supplemented for a period of six months with Se and Vit E.  Compared to the baseline period (presupplementation) of four months, statistically significant increases were observed for Se and Vit E levels, sperm motility, percent live and percent normal spermatozoa.  These improvements are likely to be “supplementation-dependent,” since all of the parameters returned to baseline values during the post-treatment period.  None of the couples reported a pregnancy during the study.  The HPLC analysis conducted on the serum of one of the patients showed the existence of at least six different Se-containing peaks, whose Se content was affected by supplementation. (MacPherson, et al, 1998)


Certain medicines may interact with Selenium.  Consult with your physician or pharmacist to determine if your medications might interact with this supplement.


Scott R, MacPherson A, Yates RW, Hussain B, Dixon J. The effect of oral selenium supplementation on human sperm motility. Department of Urology, Glasgow Royal Infirmary, UK. Br J Urol. 1998 Jul;82(1):76-80.