Safety Profile
Known Safety Concerns
- Narrow therapeutic window — UL only 3× the RDA (400 mcg/day)
- SELECT trial: possible increased prostate cancer risk in replete men
- Selenosis: hair loss, nail damage, neuropathy, garlic odour
- Multiple supplement stacking risk — selenium appears in many products
Contraindications
- Narrow therapeutic window — UL only 3× the RDA (400 mcg/day)
- SELECT trial: possible increased prostate cancer risk in replete men
Interactions
Information not yet available for this ingredient profile.
Evidence and Scientific Findings
Ingredient Overview
Selenium is an essential trace element with a narrow therapeutic window. The SELECT trial found selenium supplementation did not prevent prostate cancer and may have increased its risk in men with already-adequate selenium levels. Selenosis (selenium toxicity) causes hair loss, nail brittleness, garlic breath, GI distress, and peripheral neuropathy. The UL is 400 mcg/day — easily approached in areas with high dietary selenium or in users of multiple supplements.
Biological and Chemical Classification
- Scientific Name
- Selenium / Selenomethionine / Sodium selenite
Mechanism of Action
Information not yet available for this ingredient profile.
Clinical Evidence of Effectiveness
Information not yet available for this ingredient profile.
Pharmacokinetics
Information not yet available for this ingredient profile.
Recommended Dosage
Information not yet available for this ingredient profile.
SETI — Scientific Evidence Transparency Index
Executive Summary — Ingredient Assessment
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or RCT)
- Main clinical benefit observed: Mineral
- Evidence consistency: High consistency across studies (100%)
- Narrow therapeutic window — UL only 3× the RDA (400 mcg/day)
- SELECT trial: possible increased prostate cancer risk in replete men
- Selenosis: hair loss, nail damage, neuropathy, garlic odour
- Multiple supplement stacking risk — selenium appears in many products
The available scientific evidence for Selenium indicates notable safety signals that warrant caution. Use should be considered carefully and monitored, particularly in sensitive populations or alongside other medications.
Total SETI Score
High risk| Evidence quality | 10/40 |
| Evidence consistency | 20/20 |
| Safety signals | 0/20 |
| Study recency | 10/10 |
| Evidence transparency | 10/10 |
Evidence Summary
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or systematic review)
- 0 studies identified benefits or no safety concern (GREEN)
- 10 studies reported limited or advisory safety evidence (YELLOW)
Evidence Policy
Only peer-reviewed scientific literature indexed in PubMed or comparable databases is included in this evaluation. Commercial websites, blogs, and marketing materials are excluded. All references include direct traceable links to source documents.
Last updated: 23 მარ 2026, 15:08
Evidence Distribution
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Observational / other LOW evidence YELLOWGreen biosynthesis of selenium nanoparticles by Ralstonia insidiosa which demonstrate effectiveness against human cancer cells, Candida species and multidrug-resistant Acinetobacter baumannii. ↗Ahmed ME et al.. Green biosynthesis of selenium nanoparticles by Ralstonia insidiosa which demonstrate effectiveness against human cancer cells, Candida species and multidrug-resistant Acinetobacter baumannii.. RSC Adv. 2026. PMID:41868325.PMID 41868325 ↗Journal RSC AdvYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41868325/
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Observational / other LOW evidence YELLOWVisible Light-Mediated Synthesis of Chalcogen-Decorated 2,3-Dihydrobenzofurans in the Absence of Photocatalyst and Oxidants. ↗Arau00fajo G et al.. Visible Light-Mediated Synthesis of Chalcogen-Decorated 2,3-Dihydrobenzofurans in the Absence of Photocatalyst and Oxidants.. ACS Omega. 2026. PMID:41867606.PMID 41867606 ↗Journal ACS OmegaYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41867606/
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Observational / other LOW evidence YELLOWExperts' view on the management of scalp seborrheic dermatitis in Italy. ↗Piraccini BM et al.. Experts' view on the management of scalp seborrheic dermatitis in Italy.. J Dermatolog Treat. 2026. PMID:41867134.PMID 41867134 ↗Journal J Dermatolog TreatYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41867134/
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Observational / other LOW evidence YELLOWAutoimmunity, diet and autophagy. ↗Blaise S et al.. Autoimmunity, diet and autophagy.. Autoimmun Rev. 2026. PMID:41865949.PMID 41865949 ↗Journal Autoimmun RevYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41865949/
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Observational / other LOW evidence YELLOWmiR-7480-5p/SIRT3/GSH axis mediates selenium Deficiency-Exacerbated trimethyltin chloride-induced ferroptosis in chicken thymus. ↗Gao H et al.. miR-7480-5p/SIRT3/GSH axis mediates selenium Deficiency-Exacerbated trimethyltin chloride-induced ferroptosis in chicken thymus.. J Adv Res. 2026. PMID:41865790.PMID 41865790 ↗Journal J Adv ResYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41865790/
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Observational / other LOW evidence YELLOWPartial regeneration decreases the salt costs for ion exchange treatment of co-occurring contaminants. ↗Korak JA et al.. Partial regeneration decreases the salt costs for ion exchange treatment of co-occurring contaminants.. J Hazard Mater. 2026. PMID:41865572.PMID 41865572 ↗Journal J Hazard MaterYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41865572/
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Observational / other LOW evidence YELLOWThe Role of Antioxidants in Child Eye Health with a Focus on Myopia. ↗Didara Y et al.. The Role of Antioxidants in Child Eye Health with a Focus on Myopia.. Curr Med Chem. 2026. PMID:41863175.PMID 41863175 ↗Journal Curr Med ChemYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41863175/
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Observational / other LOW evidence YELLOWThe cytotoxic effects of glycyrrhizic acid-modified chitosan/selenium nanocomposite on osteosarcoma cancer cell line. ↗El-Ghannam G et al.. The cytotoxic effects of glycyrrhizic acid-modified chitosan/selenium nanocomposite on osteosarcoma cancer cell line.. Sci Rep. 2026. PMID:41862520.PMID 41862520 ↗Journal Sci RepYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41862520/
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Observational / other LOW evidence YELLOWLower baseline plasma selenium is associated with later suicide attempts in eating disorders: A longitudinal cohort. ↗Lengvenyte A et al.. Lower baseline plasma selenium is associated with later suicide attempts in eating disorders: A longitudinal cohort.. Prog Neuropsychopharmacol Biol Psychiatry. 2026. PMID:41862121.PMID 41862121 ↗Journal Prog Neuropsychopharmacol Biol PsychiatryYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41862121/
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Observational / other LOW evidence YELLOWGinger extract and selenium supplementation: A promising approach to improve diabetic retinopathy. ↗Huang X et al.. Ginger extract and selenium supplementation: A promising approach to improve diabetic retinopathy.. Mol Vis. 2025. PMID:41867377.PMID 41867377 ↗Journal Mol VisYear 2025Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41867377/
Score Transparency
0 of 10 approved references (score saturates at 10). More peer-reviewed studies = stronger evidence base.
Method: Q = number of approved references ÷ 10 (capped at 1.0)
Limited — mostly case reports or animal studies
Method: L = mean study-level weight across approved references. Level 1 (meta-analysis / systematic review) = 1.0; Level 2 (RCT) = 0.8; Level 3 (cohort/case-control) = 0.6; Level 4 (case report) = 0.4; Level 5 (animal / in-vitro) = 0.2.
Mixed or neutral — roughly equal benefit and risk signals
Method: D = (sum of risk-scored references − sum of benefit-scored references) ÷ total evidence score, then scaled from [−1, 1] to [0, 1]. 0.0 = pure benefit; 0.5 = neutral; 1.0 = pure risk.
One or more monitoring-level safety signals active
Method: S = 0.5 (neutral baseline) + sum of active signal severity deltas ÷ 10. Severity deltas: Critical = +2.0, High = +1.5, Moderate = +1.0, Low = +0.5. Capped at 1.0.
Final GIRI Score for Selenium. Risk level thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.
Full methodology & data sources
The GIRI Score is computed entirely from structured data — no editorial scoring or subjective weighting is applied at any step.
- References: Only approved references are counted. Each reference is assigned an evidence level (L1–L5) and a direction (risk / neutral / benefit) by the reference manager or AI classifier.
- Safety Signals: Sourced from regulatory agencies (FDA, EMA, Health Canada, TGA, and others) and pharmacovigilance databases. Only active signals count toward the score.
- Formula version: GIRI Score v3.7.0 — Q × L × D × S × 10.
- Limitations: The score reflects published evidence and recorded signals as of the last update date. It is not a clinical risk assessment and should not replace advice from a qualified healthcare professional.
Risk Level Classification
Based on available regulatory signals and scientific evidence, this ingredient presents a moderate safety concern. Caution is advised, particularly at high doses or in sensitive populations.
0–3.0
3.0–5.5
5.5–7.5
7.5–10
The score pin shows exactly where this ingredient falls on the fixed risk scale.
What drove the Moderate classification for Selenium
A score of 4.5 places this ingredient in the Moderate band. Thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.
0 approved references.
Limited — mostly case reports or animal studies (Level 4–5).
Neutral or mixed — benefit and risk signals roughly balanced.
No active signals — S component is at neutral baseline (0.5), contributing no extra risk weight.
No major regulatory restrictions or advisories recorded across monitored jurisdictions (FDA, EMA, Health Canada, TGA, and others).
How are the Low / Moderate / High / Critical thresholds defined?
The four risk levels are fixed score bands. A score is assigned to exactly one level based on where it falls:
| Level | Score | Meaning |
|---|---|---|
| LOW | 0.0 – 2.9 | Sparse or predominantly beneficial evidence. No active safety alerts. |
| MODERATE | 3.0 – 5.4 | Mixed signals — some risk alongside benefit. Caution at high doses or in sensitive groups. |
| HIGH | 5.5 – 7.4 | Multiple studies or regulatory alerts documenting adverse effects. Professional oversight recommended. |
| CRITICAL | 7.5 – 10 | Regulatory restrictions in one or more major jurisdictions. Serious documented harm. Avoid without specialist supervision. |
Thresholds are fixed constants (GIRI_Score_Utils::LEVEL_THRESHOLDS). They do not change per ingredient and are never subject to editorial adjustment.