This page shows what was measured, who it was measured in, and what that does not settle.
What Selenium does in the body
Taken as an antioxidant and for thyroid and immune support
Selenium is not something your body burns or stores as fuel. It is inserted into twenty-five specific proteins as part of an unusual amino acid, and several of those proteins are the enzymes that neutralise peroxides and that switch thyroid hormone on. If you have enough selenium to build them, they work. If you have too little, they cannot be built, and in severe deficiency the heart muscle fails. Adding more selenium than the proteins need does not make them work harder — there is no more of them to make — and the excess accumulates, which is why selenium has one of the narrowest safe ranges of any nutrient.
What happened in people
Selenium did not prevent prostate cancer in 35,533 men; hazard ratio 1.04 initially and 1.09 with extended follow-up
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 141 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Stand-in result
A stand-in result is a number measured because the real result takes too long.
A picture of it, and where the picture fails
It is like judging a journey by the speedometer rather than by arriving.
Where that stops being true. Speed does predict arrival. Many stand-in results do not predict the real one.
What people get wrong. A stand-in result is often reported as the result itself.
A surrogate endpoint substituted for a clinical endpoint, valid only where the substitution has been shown to hold.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
Pathway
A pathway is a chain of steps inside a cell, each one setting off the next.
A picture of it, and where the picture fails
A pathway is like a row of dominoes.
Where that stops being true. Dominoes fall one way. Pathways loop back and can switch themselves off.
What people get wrong. Changing one step is read as changing the outcome. Other steps often absorb it.
An ordered series of molecular interactions producing a defined cellular change.
What happened in people◇Read from sources, not yet reviewed
What was measured, goal by goal
One row for each goal a registered study measured something for. One column for each kind of thing that could be measured.
Registered studies list 40 outcome measures that RNAWiki could read. A registered study says what someone planned to measure. It does not say what they found. 0 of the matched studies tested this substance, and 0 posted a result.
There is no single score. A strong test result and a weak life result are different facts.
Goals down the side, kinds of measurement across the top. Each cell says what kind of thing was registered, not what was found.
Goal
Life outcome
What a body can do
How a person feels
A test result
A step in the body
Harms
How long
Who was studied
Fertility and sexual health
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved1 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Healthy ageing
…Waiting for a reviewer2 registered study measure of this kind. No reviewed result yet.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Which registered measures put each goal on this table
Fertility and sexual health
sperm concentration in semen; sperm motility in semen; sperm morphology in semen
Healthy ageing
all cause mortality; mortality
Sorted by fixed word lists, version v1. A name the rules do not recognise stays unsorted rather than moving to the nearest column.
What each mark on this table means
∅ Nothing in the sources checked
No registered study lists a life outcome for this goal.
△ Only a number moved
1 registered test measure.
— Not recorded
Harms were not a registered measure for this goal.
… Waiting for a reviewer
Who was studied is listed further down the page.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Incidence of prostate cancer
✗ The study did not show it
Who was studied
NCT00006392 — SELECT, selenium and vitamin E for prostate cancer prevention
Selenium HR 1.04 (99% CI 0.87 to 1.24); vitamin E HR 1.13 (99% CI 0.95 to 1.35); combination HR 1.05 (99% CI 0.88 to 1.25); no prespecified endpoint reached significance, all P > .15
Repeated elsewhere
Failed to Replicate
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. Non-significant increases in prostate cancer on vitamin E (P = .06) and in type 2 diabetes on selenium (RR 1.07, P = .16) at first analysis. With extended follow-up the vitamin E prostate cancer increase became significant at HR 1.17 (P = .008).
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Basal cell RR 1.10 (95% CI 0.95 to 1.28); squamous cell RR 1.14 (95% CI 0.93 to 1.39) — both numerically favouring placebo
Repeated elsewhere
Failed to Replicate
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. Secondary endpoints were established in 1990, seven years after randomisation began, and the blinded phase was stopped early primarily because of them. Both primary endpoints were negative, which is rarely mentioned when the secondary results are cited.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
Incidence of type 2 diabetes over a mean 7.7 years
✗ The study did not show it
Who was studied
Stranges 2007 — selenium and incidence of type 2 diabetes
How many people
1202
Study design
Secondary analysis of a randomised double-blind placebo-controlled trial
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
12.6 versus 8.4 cases per 1,000 person-years, hazard ratio 1.55 (95% CI 1.03 to 2.33); highest baseline selenium tertile HR 2.70 (95% CI 1.30 to 5.61)
Repeated elsewhere
Partially Replicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. Diabetes was a secondary outcome of the parent trial and diagnoses were self-reported, though validated in most participants. The sample was mostly older and white. The exposure-response gradient by baseline selenium is the finding hardest to dismiss.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
Median estimated dose 41,749 micrograms per day against a 55 microgram recommended allowance; mean initial serum selenium 751 micrograms/L against a reference of 125 or less
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. At 90 days or longer, 52% still had fingernail discoloration and loss, 35% fatigue and 29% hair loss. The product contained 200 times its labelled selenium concentration and reached consumers in 10 states.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
■Living longer, or avoiding a major eventEvidence recorded. Death, a heart attack, a stroke, a hospital stay.5 registered measures of this kind. No reviewed result.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
□Symptoms and quality of lifeNo evidence recorded. Pain, tiredness, mood, sleep, as the person rated it.No registered study measures this.
■A number that stands in for healthEvidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.7 registered measures of this kind.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.A human record sits on the stored organism ladder.
■AnimalsEvidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.Stored records in C. elegans (roundworm), Drosophila (fruit fly), Mouse, Rat, Dog. A result in animals says what to test next. It does not say what happens in people.
■Cells in a dishEvidence recorded. Cells or chemistry on a bench, far from a whole body.Stored mechanism abstracts describe steps measured in cells or tissue.
□A guess from softwareNo evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.
Higher on these steps means closer to something a person would feel. It does not mean better done.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Selenium
What a person takes: Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast.
The measurement behind this step
Sold in the United States as a dietary supplement under DSHEA, so no agency reviewed efficacy, safety or content before sale — a regime whose consequences the 2008 poisoning outbreak demonstrated directly, with a product carrying 200 times its declared selenium reaching consumers in ten states. Chemical form changes the pharmacokinetics substantially: selenomethionine is incorporated non-specifically into body protein and accumulates, while inorganic selenite and selenate are not stored that way. Both large prevention trials used L-selenomethionine, so their results do not straightforwardly transfer to selenite products.
Getting in
Absorbed as an amino acid, or as a salt, and the difference matters
Selenium comes in two kinds. The organic form is absorbed like an amino acid and stored in your proteins. The inorganic salts are not stored the same way.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Selenomethionine is absorbed by neutral amino acid transporters and incorporated non-specifically in place of methionine throughout the body's proteins, creating a large storage pool. Sodium selenite and selenate enter a smaller regulated pool. Both SELECT and the Nutritional Prevention of Cancer trial used L-selenomethionine, which means their results speak to the organic form and their tissue kinetics do not transfer to selenite products.
It is written into proteins by a recoded stop codon
Selenium enters proteins as a special amino acid, inserted at a position that normally means "stop". Only twenty-five human proteins are built this way.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Selenocysteine is encoded by UGA, ordinarily a stop codon, recoded in the presence of a selenocysteine insertion sequence element in the 3-prime untranslated region. The 25-member human selenoproteome includes GPX1-4, TXNRD1-3 and DIO1-3. This machinery is the reason selenium has effects at all, and the reason those effects saturate: there are only so many selenoproteins to make.
Those proteins neutralise peroxides and activate thyroid hormone
The selenium-containing enzymes clear peroxides from cells and convert thyroid hormone into its active form. That is the whole of what selenium does.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Glutathione peroxidases reduce hydrogen peroxide and lipid hydroperoxides using glutathione; thioredoxin reductases maintain the thioredoxin system; iodothyronine deiodinases remove iodine from thyroxine to generate the active triiodothyronine. The thyroid holds the highest tissue selenium concentration in the body, which is the mechanistic basis for the separate and more open question of selenium in autoimmune thyroiditis.
Synthesis saturates, and beyond it selenium turns pro-oxidant
Once there is enough selenium to build all those proteins, extra selenium does not build more. It accumulates instead, and at high enough levels it starts generating the damage it was supposed to prevent.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Plasma selenoprotein P saturates at intakes near the requirement while total plasma selenium continues rising with selenomethionine intake, so total selenium can look like improving status long after function has plateaued. Above saturation, selenium metabolites redox-cycle with cellular thiols and generate superoxide, which is the most plausible mechanistic account of the diabetes and cancer signals in the human trials.
The measured outcomes were no benefit, more diabetes, and more cancer
The two largest trials found no cancer prevention, a hazard ratio of 1.55 for diabetes in one, and a significant seventeen percent increase in prostate cancer in the vitamin E arm of the other.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
SELECT: prostate cancer hazard ratios 1.04 for selenium and 1.13 for vitamin E at first analysis, 1.09 and 1.17 with extended follow-up, the vitamin E result significant at P = .008. Nutritional Prevention of Cancer trial secondary analysis: type 2 diabetes hazard ratio 1.55 (95% CI 1.03 to 2.33), rising to 2.70 in the highest baseline selenium tertile.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What it would be like to take◇Read from sources, not yet reviewed
Felt, measured, or meaningful
Three different things that get called the same word. Registered studies measured all three, and mixing them is how a blood test becomes a health claim.
Felt
Things a person could notice without a test.
No registered study measured anything of this kind.
Measured
Things only a test, a scale or a device shows.
blood as and se concentrations and chemistry
urinary as and se concentrations and chemistry
fecal as and se concentrations and chemistry
sperm concentration in semen
seminal plasma tac
seminal plasma cat
seminal plasma sod
Meaningful
Things that change how a life goes, not only a number.
incidence of dementia
disease progression
all cause mortality
mortality
national institutes of health stroke scale
A registered study says what someone planned to measure. It does not say what they found. A number moving is not the same as a life going better. The two are shown apart here.
Felt, but not shown to help. A person notices a change. No study showed it leads anywhere good.
Measured, but not felt. A number moves. The person notices nothing. Both can be true.
Measured, but not shown to matter. A number moves in the good direction. Nobody showed that lives went better.
Matters, but takes years. The result that counts may take longer than anyone would keep watching.
Names that fit none of the three (28)
prostate cancer
pulmonary function over time by arm of study
maximum tolerated dose
skin cancer
apoptosis an proliferation rate in tumor cells
recurrence free interval
progression free interval
primary endpoint of this trial will be psa response
visually significant age related macular degeneration
cataract and best corrected visual acuity of 20/30
ejection fraction by echocardiography
cd4 count
mri tractography
modified rankin scale
control of hyperthyroidism
clinical manifestations of hyperthyroidism 1
clinical manifestations of hyperthyroidism 2
clinical manifestations of hyperthyroidism 3
clinical manifestations of hyperthyroidism 4
clinical manifestations of hyperthyroidism 5
These are harms, study-process measures, or names the rules did not recognise. They are shown rather than dropped.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
People taking multivitamins, people with Hashimoto thyroiditis, and a smaller group taking it deliberately for cancer prevention on the strength of research that has since been overturned. Genuine deficiency occurs in low-selenium soil regions, most famously parts of China where Keshan disease was endemic.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “Selenious Acid Injection is approved for use in the pediatric population, including neonates, as a source of selenium for parenteral nutrition when oral or enteral nutrition is not possible, insufficient, or contraindicated.”
US prescribing information · 49324999-50e3-43ed-a8dd-156d6dbedd9f · read 2026-08-30
On older people, the label states: “Reported clinical experience with intravenous selenious acid has not identified a difference in selenium requirements between elderly and younger patients.”
US prescribing information · 49324999-50e3-43ed-a8dd-156d6dbedd9f · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Administration of the recommended dose of Selenious Acid Injection in parenteral nutrition is not expected to cause major birth defects, miscarriage, or adverse maternal or fetal outcomes.”
US prescribing information · 49324999-50e3-43ed-a8dd-156d6dbedd9f · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary Selenium is present in human milk.”
US prescribing information · 49324999-50e3-43ed-a8dd-156d6dbedd9f · read 2026-08-30
Where the result stopped carrying
The entire selenium cancer prevention hypothesis, in the largest trial ever run to test it
Vitamin E alongside it, which produced a statistically significant increase in prostate cancer
The primary endpoints of the founding trial, which are almost never mentioned when its secondary results are cited
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied for a different goal
The studies measured something else entirely.
On this record: Some registered studies measured things that match no goal on this page.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
There was nothing to correct
Where a level is already normal, topping it up may change nothing.
On this record: Selenium is genuinely essential and correcting real deficiency eliminated an endemic fatal cardiomyopathy
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
The product may not be what it says
Contents of a sold product are not always what the label states.
On this record: This is sold as a supplement, so no agency checked what is in a given tub before it was sold.
Other reasons RNAWiki checked and found nothing for (8)
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Varies by country
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Not usually supervised: sold as a supplement or food ingredient where recorded. That is a legal category, not a safety judgement.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
The identity record classes it as a supplement ingredient; no medicines register records an approval.
No source is stored against this line.
What is in the pack
Sold in the United States as a dietary supplement under DSHEA, so no agency reviewed efficacy, safety or content before sale — a regime whose consequences the 2008 poisoning outbreak demonstrated directly, with a product carrying 200 times its declared selenium reaching consumers in ten states.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold. The rest of the recorded wording: Chemical form changes the pharmacokinetics substantially: selenomethionine is incorporated non-specifically into body protein and accumulates, while inorganic selenite and selenate are not stored that way. Both large prevention trials used L-selenomethionine, so their results do not straightforwardly transfer to selenite products.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Chronic excess produces selenosis: hair loss, nail discoloration and brittleness, garlic breath odour, fatigue, joint pain, gastrointestinal upset and, in severe cases, peripheral neuropathy. In the documented outbreak, more than half of affected people still had fingernail discoloration and loss at 90 days. Randomised evidence links 200 micrograms per day to increased type 2 diabetes incidence, with the greatest risk in those who already had the highest baseline selenium. Brazil nuts are the one common food capable of delivering a toxic intake. The tolerable upper intake level sits only a few multiples above the recommended allowance, which is the narrowest margin of any nutrient on this site.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
These are reports people sent to a regulator. They do not show the medicine caused the reaction.
Nobody counted how many people took the medicine and reported nothing.
The same event can be reported more than once, and many reports are incomplete.
News coverage, lawsuits and new warnings change how often people report.
A count is not a rate and not a risk.
Selenium appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 23007 reaction mentions were counted. One report can name several reactions.
open-targets-adr · recorded 2026-06-24 · a recorded source, not a stored snapshot
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral tablet or capsule, as selenomethionine, sodium selenite, sodium selenate or high-selenium yeast
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Chemical form changes the pharmacokinetics substantially: selenomethionine is incorporated non-specifically into body protein and accumulates, while inorganic selenite and selenate are not stored that way. Both large prevention trials used L-selenomethionine, so their results do not straightforwardly transfer to selenite products.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
211 products list this as an active ingredient in the United States drug directory. 22 of them contain it and nothing else.
FDA National Drug Code directory · 0517-6502 · read 2026-08-29
They are sold as injection, solution, liquid, pellet, powder, solution and solution/ drops, taken intragastric, intravenous, oral and sublingual.
FDA National Drug Code directory · 0517-6502 · read 2026-08-29
197 published labels name it as an active ingredient. 14 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 0b7c876b-05c6-4d70-a420-76c5470ac503 · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · 0b7c876b-05c6-4d70-a420-76c5470ac503 · read 2026-08-29
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
Watching one thing carefully can tell you whether it moved. It cannot tell you what moved it.
This is sold without a prescription, so a person can sensibly watch one thing and see whether it moves.
Pick one goal. One goal only. Two at once cannot be told apart afterwards.
Pick one thing to watch. Registered studies measured things like: blood as and se concentrations and chemistry; urinary as and se concentrations and chemistry; fecal as and se concentrations and chemistry.
Measure before you start. Take the same measurement several times first. One reading is not a starting point.
Know the swing. Write down how much it moves on its own across a normal week.
Change one thing. Change nothing else at the same time, including training and sleep.
Give it the study length. No finished study window is recorded, so no length is suggested here.
Track whether you took it. Missed days are the most common reason a home test shows nothing.
Read the trend. Look at the line across weeks. A single reading tells you almost nothing.
What not to measure
Anything that swings more day to day than the change you are looking for.
A wearable estimate of sleep stages, which is an estimate and not a measurement.
Weight on one morning, which mostly records water.
A feeling you did not write down before starting.
When to stop
Stop if something new and unpleasant starts, and ask a pharmacist or doctor.
Stop if you cannot keep everything else steady, because the result will not mean anything.
Stop at the end of the window you set, and read the trend then.
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki does not work out an amount for anyone.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That selenium prevents cancer, which two large randomised trials tested directly and rejected
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That secondary endpoints added seven years into a negative trial can establish a preventive effect
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That because selenium is an antioxidant cofactor, more of it means more antioxidant protection
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That an essential nutrient with a documented deficiency disease is therefore safe in excess
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Selenium are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
SELECT: 35,533 men, no prevention, and the trial stopped for futility
In plain words
The definitive test of selenium for preventing prostate cancer enrolled 35,533 men across three countries. Selenium did not prevent prostate cancer or any other prespecified cancer.
What was measured
Prostate cancer incidence and prespecified secondary cancer endpoints over a median 5.46 years
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Selenium and Vitamin E Cancer Prevention Trial randomised 35,533 men at 427 sites in the United States, Canada and Puerto Rico between 2001 and 2004 to selenium 200 micrograms per day as L-selenomethionine, vitamin E 400 IU per day as all-rac-alpha-tocopheryl acetate, both, or placebo, with planned follow-up of 7 to 12 years. At the 2008 analysis, median follow-up 5.46 years, hazard ratios for prostate cancer against placebo were 1.04 (99% CI 0.87 to 1.24) for selenium, 1.13 (99% CI 0.95 to 1.35) for vitamin E and 1.05 (99% CI 0.88 to 1.25) for the combination. There were no significant differences on any other prespecified cancer endpoint, all P > .15. There were statistically non-significant increased risks of prostate cancer on vitamin E (P = .06) and of type 2 diabetes on selenium (relative risk 1.07, 99% CI 0.94 to 1.22, P = .16). The authors concluded that neither agent, alone or combined, at the doses and formulations used, prevented prostate cancer. Every direction of effect in that paragraph points the wrong way for a preventive agent.
Written into the record, not signed off as a reviewed claim
With longer follow-up, vitamin E significantly increased prostate cancer
In plain words
When SELECT was followed for longer, the vitamin E arm showed a statistically significant seventeen percent increase in prostate cancer.
What was measured
Prostate cancer incidence with extended follow-up in SELECT
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Klein and colleagues reported the extended SELECT analysis with 54,464 additional person-years and 521 additional prostate cancers. Against 529 cases in the placebo group, 620 men in the vitamin E group developed prostate cancer (hazard ratio 1.17, 99% CI 1.004 to 1.36, P = .008), 575 in the selenium group (HR 1.09, 99% CI 0.93 to 1.27, P = .18), and 555 in the selenium plus vitamin E group (HR 1.05, 99% CI 0.89 to 1.22, P = .46). The absolute increase in risk per 1,000 person-years against placebo was 1.6 for vitamin E, 0.8 for selenium and 0.4 for the combination. The stated conclusion was that dietary supplementation with vitamin E significantly increased the risk of prostate cancer among healthy men. Two things deserve emphasis. This is a positive finding of harm in a trial designed to find benefit, from a nutrient marketed as protective for decades. And the combination arm was less harmful than vitamin E alone, which is the kind of interaction that makes antioxidant pharmacology in vivo unpredictable rather than reassuring.
Written into the record, not signed off as a reviewed claim
The founding trial missed both primary endpoints, and nobody remembers that
In plain words
The trial that started the selenium-and-cancer story was testing skin cancer. Selenium did not reduce skin cancer — it was numerically worse. The famous result came from secondary analyses added seven years into the trial.
What was measured
Incidence of basal and squamous cell skin carcinoma as primary endpoints, and total cancer incidence and mortality as secondary endpoints
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Clark and colleagues randomised 1,312 patients with a history of basal or squamous cell skin carcinoma to 200 micrograms of selenium daily or placebo, from 1983 to 1991, with a mean treatment period of 4.5 years and total follow-up of 6.4 years. The primary endpoints were incidences of basal and squamous cell skin carcinoma, and selenium did not affect either: 377 new basal cell cancers on selenium against 350 on control (RR 1.10, 95% CI 0.95 to 1.28) and 218 squamous cell cancers against 190 (RR 1.14, 95% CI 0.93 to 1.39). Both numerically favoured placebo. The secondary endpoints, established in 1990 — seven years after randomisation began — showed reduced total cancer mortality (29 versus 57 deaths, RR 0.50, 95% CI 0.31 to 0.80), reduced total cancer incidence (77 versus 119, RR 0.63, 95% CI 0.47 to 0.85), and reductions in lung, colorectal and prostate cancer. The blinded phase was stopped early primarily because of those secondary findings. That decision — stopping a trial early on endpoints added mid-course, after the prespecified ones had failed — is what put selenium in millions of multivitamins and what SELECT was built to confirm.
Written into the record, not signed off as a reviewed claim
The same trial's data showed selenium raised type 2 diabetes risk by 55 percent
In plain words
A later analysis of the founding trial found that people taking selenium developed type 2 diabetes more often, with the highest risk in those who already had the most selenium in their blood.
What was measured
Incidence of type 2 diabetes per 1,000 person-years, stratified by baseline plasma selenium tertile
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Stranges and colleagues analysed diabetes incidence among 1,202 participants in the Nutritional Prevention of Cancer trial who did not have type 2 diabetes at baseline, in low-selenium areas of the eastern United States. Over a mean 7.7 years, type 2 diabetes developed in 58 selenium recipients and 39 placebo recipients — 12.6 versus 8.4 cases per 1,000 person-years, hazard ratio 1.55 (95% CI 1.03 to 2.33). The lack of benefit persisted across strata of age, sex, body mass index and smoking. Critically, an exposure-response gradient was found across tertiles of baseline plasma selenium, with a significantly increased risk in the highest tertile (hazard ratio 2.70, 95% CI 1.30 to 5.61). The authors concluded selenium does not seem to prevent type 2 diabetes and may increase risk. Diabetes was a secondary outcome and diagnoses were self-reported, which the authors state as limitations. But the exposure-response gradient — most harm in those who started with the most selenium — is exactly the pattern a genuine toxicity produces and the opposite of what a repletion effect looks like.
Written into the record, not signed off as a reviewed claim
A manufacturing error poisoned 201 people across ten states
In plain words
A liquid supplement was made with two hundred times the selenium on its label. Two hundred and one people were poisoned, and half still had nail damage three months later.
What was measured
Serum and urine selenium concentrations, symptom prevalence at onset and at 90-day follow-up
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
MacFarquhar and colleagues investigated an outbreak of acute selenium poisoning traced to a liquid dietary supplement containing 200 times its labelled selenium concentration. Two hundred and one cases were identified across 10 states, with one hospitalisation. The median estimated selenium dose consumed was 41,749 micrograms per day against a recommended dietary allowance of 55 micrograms. Reported symptoms included diarrhoea in 78%, fatigue 75%, hair loss 72%, joint pain 70%, nail discoloration or brittleness 61% and nausea 58%. At 90 days or longer, 52% still had fingernail discoloration and loss, 35% fatigue and 29% hair loss. Mean initial serum selenium in 8 patients was 751 micrograms per litre against a reference of 125 or less, and mean initial urine selenium in 7 patients was 166 micrograms per 24 hours against a reference of 55 or less. The authors' conclusion is the audit: "Had the manufacturers been held to standards used in the pharmaceutical industry, it may have been prevented." Selenium's narrow margin between requirement and toxicity makes it the nutrient least tolerant of the manufacturing regime it is sold under.
Written into the record, not signed off as a reviewed claim
Selenium is genuinely essential, and the deficiency disease is real
In plain words
In parts of China with selenium-poor soil, deficiency caused a fatal heart muscle disease in children and young women. Supplementation essentially eliminated it.
What was measured
Recommended dietary allowance of 55 micrograms per day against the 200 micrograms per day used in the prevention trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Selenium is incorporated as selenocysteine into 25 human selenoproteins, including the glutathione peroxidases, the thioredoxin reductases and the iodothyronine deiodinases that activate thyroid hormone. Severe deficiency in low-soil-selenium regions produced Keshan disease, an endemic cardiomyopathy, and supplementation programmes largely eliminated it — one of the clearest nutritional public health successes recorded. This is the fact that every selenium supplement claim leans on, and it is genuine. It is also, precisely, a deficiency effect. The 200 microgram daily doses used in the Nutritional Prevention of Cancer trial and in SELECT were nearly four times the recommended dietary allowance of 55 micrograms, administered to populations that were not deficient, on the hypothesis that more selenoprotein activity would prevent cancer. Selenoprotein synthesis saturates; the doses did not.
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What is not here
4 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
Selenium is genuinely essential and cures a real deficiency cardiomyopathy, but the cancer prevention hypothesis it carried for twenty years was tested in 35,533 men and produced a prostate cancer hazard ratio of 1.09, no benefit on any prespecified endpoint, and a diabetes signal that a separate analysis of the founding trial put at a hazard ratio of 1.55.
Recorded evidence blocks (14)
Q1
What did Selenium's largest trial (35533 people) and its longest (19 years) measure?
35533 people in Selenium's largest registered study, 19 years in its longest registered window, measuring Number of Participants With Visually Significant Age-related Macular Degeneration (AMD). ClinicalTrials.gov · 2026-09-01
26 phase3, 19 na, 15 phase2, 11 phase1, 3 phase4, 2 na or unstated, 1 early phase1; NCT00008385; 2019-11. Last human test completed 2025, NCT06362005.
Interpretation These counts include studies where Selenium was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.
Show the evidence
phase3
26
na
19
phase2
15
phase1
11
phase4
3
na or unstated
2
2 more recorded rows
early phase1
1
Last recorded human testNCT06362005
2025-10-01
recorded 2026-09-01 · last checked 2026-09-04
Q2
From C. elegans to human: where has Selenium shown lifespan?
"Concluded - Terminated by PI"; 9 of 69 registered studies
Show the evidence
Trial
NCT00078897
terminated; "Concluded - Terminated by PI"
NCT00212212
terminated; "Insufficient funds to complete study."
NCT00395161
terminated; "Terminated for futility on 11/30/09 based on the recommendation of the DSMB"
NCT01212965
terminated; "The investigators chose to terminate the study due to participant attrition. Of the limited data evaluable, none of the patients experienced adverse events."
NCT01390506
withdrawn; "The company did not provide the study product"
NCT02112643
withdrawn; "Lack of funding"
3 further recorded trials
NCT02393183
withdrawn; "Do not access to the drug"
NCT04296578
withdrawn; "Study did not start"
NCT05672095
withdrawn; "Abandoned"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Selenium used 100 µg selenium — over how long?
2025; "The relationship between selenium biomarkers and epigenetic clock measures was analyzed using linear regression analyses."
DunedinPACEPMID 40275394
2025; "Participants with deficient serum selenium levels (< 90 μg/L) had a higher rate of biological aging (DunedinPACE, β = - 0.02, SE = 0.01, 95% CI - 0.033 to - 0.004, p = 0.010, n = 865)."
epigenetic clockPMID 40275394
2025; "Our study suggests that low levels of selenium biomarkers are associated with accelerated biological aging measured through epigenetic clocks."
DunedinPACE
2024; "Participants with deficient serum selenium levels (<90μg/L) had a higher rate of biological aging (DunedinPACE, p=0.01, n=865)."
GrimAgePMID 38113735
2024; "PhenoAge-Accel, GrimAge-Accel, and DNAm-MS mediated a separate 6.5%, 12.3%, 6.0% of the positive association between Cu and all-cause mortality; GrimAge-Accel mediated 14.3% of the inverse association of selenium with all-cause mortality."
recorded 2025-04-25 · last checked 2026-09-04
Q6
More Selenium was worse in human: at what point?
U-shaped in human: "At the lowest levels of baseline intake, selenium supplementation appeared instead to have beneficial effects on the lipid profile, with an overall indication of U-shaped curves, apart from HDL-cholesterol." Europe PMC · dose-response search · 2026-03-01
8 recorded sentences naming Selenium; U-shaped, dose-response, Dose-response
Show the evidence
U-shaped
PMID 40243093
"At the lowest levels of baseline intake, selenium supplementation appeared instead to have beneficial effects on the lipid profile, with an overall indication of U-shaped curves, apart from HDL-cholesterol."
PMID 41250018
"Additionally, non-linear dose-response analysis indicated a U-shaped association between circulating selenium and risk of hypertension (P <sub>non-linearity</sub> < 0.001)."
PMID 41250018
"This systematic review and dose-response meta-analysis suggests a U-shaped association between circulating selenium and the risk of hypertension in representative and general adults."
dose-response
PMID 40243093
"However, dose-response meta-analyses analyzing the effects of selenium administration on the lipid profile in experimental human studies are lacking."
PMID 40243093
"Through a restricted cubic spline regression meta-analysis, the dose-response relation between the dose of selenium administered or blood selenium concentrations at the end of the trials and changes over time in blood lipids, ie, total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and triglycerides was assessed."
Dose-responsePMID 40243093
"Dose-response analysis indicated that selenium administration at and above 200 µg/day decreased HDL and LDL cholesterol and increased triglyceride levels."
dose-response
PMID 40243093
"In this dose-response meta-analysis of experimental human studies, an adverse effect of selenium administration on blood lipids at levels around or above the current upper level of intake was observed."
PMID 41250018
"However, based on linear dose-response analysis, there was no significant association per 50 µg/L increment in circulating selenium and risk of hypertension."
recorded 2026-03-01 · last checked 2026-09-04
Q7
Could one person measure Selenium's effect on prostate cancer?
Prostate cancer: measured in Selenium's trials.
Interpretation prostate cancer is the recorded endpoint.
Show the evidence
biomarkers
prostate cancer; 2026-09-01
incidence of dementia; 2026-09-01
pulmonary function over time by arm of study; 2026-09-01
maximum tolerated dose; 2026-09-01
skin cancer; 2026-09-01
apoptosis an proliferation rate in tumor cells; 2026-09-01
14 more recorded rows
biomarkers
recurrence free interval; 2026-09-01
biomarkers
progression free interval; 2026-09-01
biomarkers
primary endpoint of this trial will be psa response; 2026-09-01
biomarkers
disease progression; 2026-09-01
biomarkers
visually significant age related macular degeneration; 2026-09-01
biomarkers
cataract and best corrected visual acuity of 20/30; 2026-09-01
biomarkers
all cause mortality; 2026-09-01
biomarkers
ejection fraction by echocardiography; 2026-09-01
biomarkers
cd4 count; 2026-09-01
biomarkers
mri tractography; 2026-09-01
biomarkers
mortality; 2026-09-01
biomarkers
blood as and se concentrations and chemistry; 2026-09-01
biomarkers
urinary as and se concentrations and chemistry; 2026-09-01
biomarkers
fecal as and se concentrations and chemistry; 2026-09-01
human trials at or under30
14
Not recorded for this substance
a recorded half-life
smallest human trial
0; NCT01390506; PHASE2; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; WITHDRAWN
Q8
Which of all cause mortality, apoptosis an proliferation rate in tumor cells and blood as and se concentrations and chemistry did Selenium's trials measure?
all cause mortality, apoptosis an proliferation rate in tumor cells and blood as and se concentrations and chemistry lead 40 outcome terms across Selenium's trials. ClinicalTrials.gov · 2026-09-01
Interpretation maximum tolerated dose, skin cancer, apoptosis an proliferation rate in tumor cells, recurrence free interval, progression free interval and primary endpoint of this trial will be psa response follow.
Show the evidence
prostate cancer
1
incidence of dementia
1
pulmonary function over time by arm of study
1
maximum tolerated dose
1
skin cancer
1
apoptosis an proliferation rate in tumor cells
1
14 more recorded rows
recurrence free interval
1
progression free interval
1
primary endpoint of this trial will be psa response
1
disease progression
1
visually significant age related macular degeneration
1
cataract and best corrected visual acuity of 20/30
1
all cause mortality
1
ejection fraction by echocardiography
1
cd4 count
1
mri tractography
1
mortality
1
blood as and se concentrations and chemistry
1
urinary as and se concentrations and chemistry
1
fecal as and se concentrations and chemistry
1
recorded 2026-09-01 · last checked 2026-09-04
Q9
What will the one ongoing trial of Selenium report, and when?
Interpretation Change in Left Ventricular Ejection Fraction (LVEF)
Show the evidence
TrialNCT07334197
"Effect of Melatonin on Left Ventricular Reverse Remodeling and Inflammation in Peripartum Cardiomyopathy"; n 25; "Change in Left Ventricular Ejection Fraction (LVEF)"; 2029-12-30
recorded 2026-09-01 · last checked 2026-09-04
Q10
Which 38 trials of Selenium posted no result?
Posted no result
38 of 38 completed trials
Registrations
NCT00022165, NCT00978718, NCT00170404, NCT00197561, NCT00752739 and NCT00186706, and 32 more
Completion dates
oldest 2002-01; newest 2024-08
Show the evidence
Trial
NCT00022165
2002-01
NCT00978718
2004-06
NCT00170404
2005-10
NCT00197561
2006-08
NCT00752739
2007-04
NCT00186706
2007-11
14 further recorded trials
NCT00112892
2007-12
NCT00064194
2008-04-30
NCT00217516
2008-10
NCT00428649
2008-10
NCT00188604
2009-01
NCT01442727
2009-04
NCT00063453
2010-08
NCT00446901
2011-01
NCT02121457
2012-08
NCT00149656
2013-04
NCT00832039
2013-06
NCT01327755
2013-08
NCT02026856
2013-12
NCT01247077
2014-04
Q11
At the median, Selenium's trials enrolled 78 people — anything larger?
Median enrolment
78
Largest enrolment
35533
Registered trials counted
69
Q12
What do 23007 spontaneous reports say about Selenium — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Selenium appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 23007 reaction mentions were counted: pain 2762; alopecia 2564; pemphigus 2523; systemic lupus erythematosus 2523. open-targets-adr · CHEMBL6068503 · 2026-06-24
Show the evidence
pain
2762
alopecia
2564
pemphigus
2523
systemic lupus erythematosus
2523
abdominal discomfort
2489
rheumatoid arthritis
2273
4 more recorded rows
fatigue
2269
glossodynia
2063
swelling
1838
hand deformity
1703
recorded 2026-06-24 · last checked 2026-09-04
Q13
Was Selenium studied with fasting?
fasting is named in Selenium's label sentences: "In conclusion, our study findings indicate some benefits of selenium on fasting insulin, and QUICKI compared with placebo, but elicits no effect on HbA1c, HOMA-IR, and FBS." openfda-label+europepmc · 2023-08-11
1 recorded statement; fasting
Show the evidence
fasting
In conclusion, our study findings indicate some benefits of selenium on fasting insulin, and QUICKI compared with placebo, but elicits no effect on HbA1c, HOMA-IR, and FBS.
recorded 2023-08-11 · last checked 2026-09-04
Q14
What is recorded about Selenium and AMPK?
"These pathologies were associated with a systemic selenium deficit, elevated oxidative stress, suppressed testicular glycolysis (evidenced by reduced GLUT1/3/8 expression and ATP levels), and inhibition of the AMPK/SIRT1/PGC-1α pathway." — where Selenium and AMPK appear together. Europe PMC · pathway abstract search · 2026-08-12
"These pathologies were associated with a systemic selenium deficit, elevated oxidative stress, suppressed testicular glycolysis (evidenced by reduced GLUT1/3/8 expression and ATP levels), and inhibition of the AMPK/SIRT1/PGC-1α pathway."
sirtuinPMID 42155248
"These pathologies were associated with a systemic selenium deficit, elevated oxidative stress, suppressed testicular glycolysis (evidenced by reduced GLUT1/3/8 expression and ATP levels), and inhibition of the AMPK/SIRT1/PGC-1α pathway."
AMPKPMID 42155248
"Strikingly, the combined treatment most effectively restored systemic and testicular selenium status, normalized redox balance, enhanced glycolytic flux and lactate transporter (MCT4/CD147) regulation, and robustly activated the AMPK/SIRT1 signaling cascade."
sirtuinPMID 42155248
"Strikingly, the combined treatment most effectively restored systemic and testicular selenium status, normalized redox balance, enhanced glycolytic flux and lactate transporter (MCT4/CD147) regulation, and robustly activated the AMPK/SIRT1 signaling cascade."
AMPKPMID 42155248
"This protective effect is mechanistically linked to the restoration of selenium-dependent antioxidant capacity and the AMPK/SIRT1 pathway-mediated enhancement of testicular glycolytic metabolism."
sirtuinPMID 42155248
"This protective effect is mechanistically linked to the restoration of selenium-dependent antioxidant capacity and the AMPK/SIRT1 pathway-mediated enhancement of testicular glycolytic metabolism."
6 more recorded rows
mTORPMID 42656336
"Current evidence indicates that selenium-based agents primarily exert antitumor effects through disruption of redox homeostasis, induction of apoptosis, and modulation of survival signaling pathways such as PI3K/AKT/mTOR, while additional effects on autophagy, metastasis, angiogenesis, and treatment resistance appear to be more context-dependent."
autophagyPMID 42656336
"Current evidence indicates that selenium-based agents primarily exert antitumor effects through disruption of redox homeostasis, induction of apoptosis, and modulation of survival signaling pathways such as PI3K/AKT/mTOR, while additional effects on autophagy, metastasis, angiogenesis, and treatment resistance appear to be more context-dependent."
IGF-1PMID 41996863
"Serum concentrations of selenium (Se), iron (Fe), chromium (Cr), and magnesium (Mg) were quantified using atomic absorption spectrophotometry, while tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), interleukin-6 (IL-6), and IGF-1 were measured via enzyme-linked immunosorbent assay (ELISA)."
mTORPMID 41496977
"Simultaneously, selenium impairs tumor growth by halting the cell cycle and suppressing proliferative signals via PI3K/Akt/mTOR and MAPK pathways."
NAD+PMID 40809343
"Herein, a precision nanodrug delivery system (MSe-NAD<sup>+</sup>/Nes) has been designed, incorporating mesoporous selenium nanozymes (MSe NPs) and leveraging a neutrophil-targeting strategy, to accomplish accurate delivery and mitigate inflammation."
autophagyPMID 40794323
"Selenium notably enhanced the expression of antioxidant genes (superoxide dismutase and glutathione peroxidase) and inhibited apoptosis and autophagy pathways."
recorded 2026-08-12 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · Open Targets 26.06 — CC0 · derived from this page's own recorded fields; no external licence · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 5 required field(s) not terminal: Why people use it, Best-supported result, Most important common problem, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 12 source rows
✓ no critical contamination: no quarantine open
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This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.