Selenium
What the evidence shows
The landmark Clark NPC trial found a striking reduction in prostate cancer incidence with selenium supplementation — but the later, larger SELECT trial found no benefit and a possible diabetes risk signal at high doses, muddying the picture considerably. Selenium is a genuine essential nutrient, but 'more selenium' is not clearly protective beyond correcting a deficiency.
How it's thought to work
Cofactor for glutathione peroxidase and other antioxidant enzymes; also relevant to sperm structural integrity during maturation.
Typical Dosage
100–200mcg/day as selenomethionine — do not exceed 400mcg/day.
Safety Notes
Narrow safety margin compared to most minerals here — selenium toxicity is real at sustained high intake. Don't stack multiple selenium-containing supplements without checking total daily dose.
Want the full clinical breakdown?
Selenium is required for testosterone synthesis and is concentrated in testicular tissue. Deficiency is common — and correcting it with 200mcg/day improves sperm motility and may raise testosterone.
Read the full evidence reviewConsidering adding Selenium to your routine?
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