Selenium
The verdict
Essential for sperm production; supplementation trials mixed, one combo study showed some markers worsening.
A trace element required for testosterone biosynthesis and spermatogenesis; sold standalone and combined with vitamin E in many products.
What the evidence shows
Mechanistically essential; supplementation-trial evidence mixed. One combined selenium + vitamin E meta-analysis found reduced semen volume and total sperm count, alongside improved vitality and normal morphology — a genuinely mixed result.
Evidence tier
Non-Cochrane evidence🟡 Smaller systematic reviews/meta-analyses or RCTs exist, no Cochrane-grade synthesis. Emerging, not proven.
Sources
Take this further
Last reviewed .