Selenium
Selenium (Selenomethionine, Sodium Selenite)
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Essential nutrient; not approved as a testosterone therapy
Reference only. Not medical advice.
What can go wrong
Selenium has a narrow safety margin. Chronic intake above the 400 mcg upper limit can cause selenosis: hair and nail brittleness or loss, GI upset, garlic breath, and neuropathy. The SELECT trial context also raised concerns about high-dose selenium and prostate-related outcomes, so routine high-dose use is discouraged.
This is something to take to a clinician. The Atlas can tell you what is known about selenium in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Selenium is an essential trace element concentrated in the testis and required for selenoproteins that protect sperm from oxidative damage. Trials in subfertile men, often combined with other antioxidants, suggest improved sperm parameters, but evidence that supplementing selenium raises testosterone in well-nourished men is weak. The therapeutic window is narrow: too much is toxic.
A fertility-support antioxidant, not a testosterone lever in replete men.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
Combinations named above are how people use these compounds together, under names the community gave them. The combinations themselves have not been studied. Evidence for one compound is not evidence for a pair.
How it is supposed to work
Selenium is incorporated into selenoproteins such as glutathione peroxidase and a structural selenoprotein in the sperm mitochondrial sheath. Adequate selenium protects developing sperm from oxidative stress; deficiency impairs spermatogenesis. This is a deficiency-correction mechanism, not a pharmacologic testosterone effect.
What people get wrong
Often saidSelenium boosts testosterone
ActuallyIts documented benefits are on sperm in deficient or subfertile men, not on raising testosterone in replete men.
Often saidIf a little helps, more is better
ActuallySelenium is toxic above ~400 mcg/day; over-supplementation causes selenosis.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
What we do not know
- Does benefit exist only in selenium-deficient or oxidatively-stressed men?
- What is the optimal dose that helps sperm without prostate risk?
At a glance
- RDA (adult men)
- ~55 mcg/day
- Upper limit
- 400 mcg/day
- Role
- Selenoprotein antioxidant defense in testis
- Best evidence
- Sperm quality in subfertile men
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Selenium. A short entry is not a safe entry.
- Timeline. We have not built the dated record of research and regulatory events.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Scott et al. and similar antioxidant-in-subfertility trialsvarious
Selenium (often with vitamin E) improved sperm motility/morphology in subfertile men
SELECT trial (selenium and vitamin E, prostate context)2009
No prostate-cancer prevention benefit; underscored that high-dose selenium is not a free upside