Supplement

Selenium

Essential trace mineral in antioxidant enzymes and thyroid physiology.[2068,2928,3394, etc.]

Superscript reference numbers link to the Sources bibliography.

Strong Evidence

Immune SupportHormone HealthLongevityalias: selenomethionine

Composite Rating

3.8/5

Blends evidence depth, community direction, safety friction, and completeness.

Evidence Intensity

100/100

High depth from human/RCT/meta counts

Community Direction

Mixed / Neutral • confidence Minimal

Safety Friction

100/100

High signal from adverse/interaction markers

Data Completeness

100%

Studies 15 • mentions 5 • links 25

Not medical advice. This product is for educational and informational purposes only. It does not diagnose, treat, cure, or prevent any disease and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition.

FDA disclaimer: These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Results may vary. Not intended for use by pregnant or nursing women, individuals under 18, or those with known medical conditions without physician consultation.

If you are experiencing a medical emergency, call 911 or your local emergency number immediately.

Implementation Blueprint

Goal alignment: Immune Support, Hormone Health, Longevity.[623,765,1003, etc.]

Dose guide: Human-study daily dose: 0.2 mg/day (moderate-confidence extraction from PubMed abstracts)..[623,765,1003, etc.]

Category: mineral.[623,765,1003, etc.]

Safety and Pitfalls

Excess intake risks selenosis; avoid chronic high doses[623,765,1003, etc.]
Potential side effect: brittle nails[623,765,1003, etc.]
Potential side effect: metallic taste at high dose[623,765,1003, etc.]
ODS safety note: In addition, selenium deficiency may increase the risk of congenital hypothyroidism in infants by exacerbating iodine deficiency.[623,765,1003, etc.]
ODS safety note: A 2018 systematic review and meta-analysis of 41 studies found that selenium supplements (doses not indicated) reduce the risk of Keshan disease by 86% [ 38 ].[623,765,1003, etc.]
ODS safety note: Selenium deficiency could exacerbate iodine deficiency, potentially increasing the risk of congenital hypothyroidism in infants [ 3 , 8 ].[623,765,1003, etc.]
ODS safety note: Groups at Risk of Selenium Inadequacy Although selenium deficiency is uncommon in the United States, some groups of people have a higher risk of inadequate intakes.[623,765,1003, etc.]
ODS safety note: These groups include people who live in selenium-deficient regions, those undergoing kidney dialysis, and those living with HIV.[623,765,1003, etc.]
ODS safety note: However, people in some countries whose diet consists primarily of vegetables grown in low-selenium areas are at risk of deficiency [ 13 ].[623,765,1003, etc.]
ODS safety note: People undergoing kidney dialysis Selenium concentrations are often significantly lower in patients who are undergoing long-term hemodialysis than in healthy individuals partly because hemodialysis removes some selenium from the blood [ 43-46 ].[623,765,1003, etc.]
ODS safety note: In addition, hemodialysis patients are at risk of low dietary selenium intakes due to anorexia resulting from uremia and dietary restrictions [ 44 , 46 , 47 ].[623,765,1003, etc.]
ODS interaction note: Food and Drug Administration (FDA) developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet.[623,765,1003, etc.]
ODS interaction note: Food and Drug Administration (FDA) allowed two qualified health claims that some scientific evidence suggests consumption of selenium “may reduce the risk of certain forms of cancer” and “may produce anticarcinogenic effects.” However, FDA determined that this evidence is limited and not conclusive [ 65 ].[623,765,1003, etc.]
ODS interaction note: Interactions with Medications Selenium supplements may interact with medications.[623,765,1003, etc.]
Legacy caution group: Those already consuming Brazil nuts regularly (very high selenium)[623,765,1003, etc.]
Legacy caution group: Don't exceed 400mcg/day total[623,765,1003, etc.]

At-A-Glance Evidence Architecture[2068,2928,3394, etc.]

Clinical Depth

Humans: 6,056 • RCTs: 621 • Meta: 177

Cohort / Real-World

Cohort signals: 0

Safety Markers

Adverse signals: 5,090 • Interactions: 3,832

Evidence Tracking

Freshness, trend, and study timeline for this item

Evidence Tracking

Status

New Evidence

Trend

→ Stable evidence base

Depth

12067 total studies · 2 recent

Timeline

20112024

Top Signal Metrics[2068,2928,3394, etc.]

Animal-only studies

13,430

Total indexed

12,067

Human studies

6,056

Safety adverse signals

5,090

Interaction signals

3,832

In vitro / tissue

3,658

Community Direction Mix[623,765,1003, etc.]

Weighted direction score: 2 (Mixed / Neutral)

Benefit2 (40%)

Adverse1 (20%)

No Effect1 (20%)

Mixed1 (20%)

Evidence Quality Summary[2068,2928,3394, etc.]

High when >=2 human meta-analyses, or >=5 human RCTs with substantial human literature volume.

Animal-only studies

13,430

Total indexed

12,067

Human studies

6,056

Safety adverse signals

5,090

Interaction signals

3,832

In vitro / tissue

3,658

Randomized trials

621

Meta-analyses

177

Study Type Breakdown

Distribution of evidence by study design strength

Meta-AnalysesLevel 1a177

Randomized TrialsLevel 1b621

Human Studies (other)Level 3-45,258

All IndexedAll levels12,067

100

Evidence Strength: High

Composite of study volume, RCTs, and meta-analyses

Top Human Studies[2068,2928,3394, etc.]

PMID 35365361 • 2022 Jun

ESPEN micronutrient guideline.

Clin Nutr

Open PubMed

PMID 38243784 • 2024 Mar

Selenium Supplementation in Patients with Hashimoto Thyroiditis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.

Thyroid

Open PubMed

PMID 39698034 • 2024

Effects of different supplements on Hashimoto's thyroiditis: a systematic review and network meta-analysis.

Front Endocrinol (Lausanne)

Open PubMed

PMID 29376219 • 2018 Jan 29

Selenium for preventing cancer.

Cochrane Database Syst Rev

Open PubMed

PMID 37065742 • 2023

The association between micronutrient levels and diabetic foot ulcer: A systematic review with meta-analysis.

Front Endocrinol (Lausanne)

Open PubMed

PMID 36940841 • 2023 Jun

Non-pharmacological interventions in the treatment of rheumatoid arthritis: A systematic review and meta-analysis.

Autoimmun Rev

Open PubMed

PMID 33650299 • 2021 Jul

Effect of selenium on thyroid autoimmunity and regulatory T cells in patients with Hashimoto's thyroiditis: A prospective randomized-controlled trial.

Clin Transl Sci

Open PubMed

PMID 37357646 • 2023 Jun

Efficacy and tolerability of an oral supplement containing amino acids, iron, selenium, and marine hydrolyzed collagen in subjects with hair loss (androgenetic alopecia, AGA or FAGA or telogen effluvium). A prospective, randomized, 3-month, controlled, assessor-blinded study.

Skin Res Technol

Open PubMed

PMID 37513551 • 2023 Jul 13

The Effects of Zinc and Selenium Co-Supplementation on Resting Metabolic Rate, Thyroid Function, Physical Fitness, and Functional Capacity in Overweight and Obese People under a Hypocaloric Diet: A Randomized, Double-Blind, and Placebo-Controlled Trial.

Nutrients

Open PubMed

PMID 21990298 • 2011 Oct 12

Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

JAMA

Open PubMed

PMID 31511230 • 2019 Sep 11

Effects of Helicobacter pylori treatment and vitamin and garlic supplementation on gastric cancer incidence and mortality: follow-up of a randomized intervention trial.

BMJ

Open PubMed

PMID 35784564 • 2022

Add-On Effect of Selenium and Vitamin D Combined Supplementation in Early Control of Graves' Disease Hyperthyroidism During Methimazole Treatment.

Front Endocrinol (Lausanne)

Open PubMed

PMID 34970669 • 2022 Aug 1

Nutritional Supplements and Complementary Therapies in Polycystic Ovary Syndrome.

Adv Nutr

Open PubMed

PMID 34959972 • 2021 Dec 10

Diet and Anxiety: A Scoping Review.

Nutrients

Open PubMed

PMID 32545596 • 2020 Jun 12

Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function?

Nutrients

Open PubMed

Community Report Frequency[623,765,1003, etc.]

Benefit reports: 2

Adverse reports: 1

No-effect reports: 1

Mixed reports: 1

Unclear reports: 0

Signal confidence: 0.00

Top Reported Effects[623,765,1003, etc.]

Benefits

Thyroid hormone activation and protection: 1
Antioxidant defense via glutathione peroxidase: 1
Immune function support: 1
May reduce cancer risk (some cancers): 1
Reproductive health: 1
May reduce autoimmune thyroiditis progression: 1

Adverse

Those already consuming Brazil nuts regularly (very high selenium): 1
Don't exceed 400mcg/day total: 1

No Effect

no noticeable effect: 1

Typically treated as a correction nutrient, not a performance supplement. | Step2: Insufficient empirical signal for a directional adjustment.

Reddit evidence: 0 mentions (confidence 0.00).

Amazon signal: 0 products scanned (confidence 0.00).

GNC signal: 0 products scanned (confidence 0.00) [BLOCKED].

PerimeterX / captcha block encountered.

Search fetch failed: Failed to fetch after retries: https://old.reddit.com/search.json?raw_json=1&sort=relevance&t=year&limit=12&q=%22selenium%22%20(supplement%20OR%20dosage%20OR%20stack%20OR%20side%20effects%20OR%20review)%20(subreddit%3ASupplements%20OR%20subreddit%3ANootropics%20OR%20subreddit%3ABiohackers%20OR%20subreddit%3Alongevity%20OR%20subreddit%3ANutrition%20OR%20subreddit%3AHubermanLab%20OR%20subreddit%3ASleep%20OR%20subreddit%3AFitness%20OR%20subreddit%3Aketoscience%20OR%20subreddit%3AStackAdvice)

Fallback search failed: Failed to fetch after retries: https://old.reddit.com/search.json?raw_json=1&sort=comments&t=all&limit=16&q=%22selenium%22%20(supplement%20OR%20capsule%20OR%20powder%20OR%20experience%20OR%20results%20OR%20side%20effects)

Broad search failed: Failed to fetch after retries: https://old.reddit.com/search.json?raw_json=1&sort=new&t=all&limit=16&q=selenium

Use adverse/interactions PubMed signal counts for screening; perform clinician review before high-dose or multi-drug stack use.

ODS fact sheet linked for safety review.

Human-study daily dose signal: 0.2 mg/day (confidence MEDIUM).

Extracted from 2 dosing mentions across 1 PubMed studies (mg/day).

Imported legacy community score: 7.0/10 (heuristic mapping confidence 1.00).

Imported legacy monthly cost signal: ~$8.00.

Community Evidence Examples[623,765,1003, etc.]

aggregate • benefit

Aggregate community signal: 5 directional mentions (benefit 2, adverse 1, no-effect 1, mixed 1).

Open mention

Retail Signal Examples

amazon

Amazon search for Selenium

Rating: n/a | Reviews: n/a

Open product

Primary Source Links

Evidence Sources

Community Sources

Scientific Evidence Notes[2068,2928,3394, etc.]

1. Selenium status and thyroid outcomes

COHORT • 2020 • Adults

Population studies and deficiency settings.

Outcome: Deficiency correction improves selected thyroid markers.[2068,2928,3394, etc.]

2. PubMed evidence summary: Selenium

PUBMED • Humans + preclinical triage

Counts aggregated from automated literature sweep and tiering rules.

Outcome: Tier HIGH; humans 6056, RCTs 621, meta-analyses 177.[2068,2928,3394, etc.]

Open source

3. ESPEN micronutrient guideline.

PUBMED • 2022 • Human evidence curation set

PMID 35365361 from Clin Nutr.