Cofactor of 25 selenoproteins including GPX (antioxidant GSH peroxidase), IDD (thyroid deiodinase T4→T3), TXN (redox) and SEPP1 (transport). Spanish soil is geologically poor · 50% Spanish adults functional deficiency.
6Selenium appears in 6 protocols personalizable→Unique trace mineral · forms 25 selenoproteins encoded with selenocysteine (Sec, 21st amino acid). Antioxidant cofactor GSH peroxidase + thyroid + cancer prevention.
Selenium is the only trace mineral incorporated into proteins via a specific amino acid, selenocysteine (Sec), encoded by the UGA codon (normally STOP, recoded via SECIS element). Humans synthesize 25 selenoproteins including: GPX1-4 (glutathione peroxidase, antioxidant reducing H₂O₂ and lipoperoxides), DIO1/2/3 (thyroid deiodinase, converts T4 → active T3), TXN (thioredoxin reductase, redox), SEPP1 (plasma Se transporter), MsrB1 (repairs oxidized proteins).
Soil content is the main source and varies geographically: regions of Finland, central China, NZ are chronically low · USA Great Plains regions are high. Spain has geologically poor Se soil (Mediterranean and northern coast zones especially) · 50% Spanish adults have plasma Se <90 µg/L (functional deficiency per Combs 2024). L-selenomethionine (Se incorporated into methionine via host plant) is the organic form with best bioavailability + safety profile. NEVER selenate/selenite megadose (NPC trial 2008 +20% T2D incidence with 200 mcg/d × 5 years + high-dose cardiotoxicity).
5 pivotal studies · coverage of Hashimoto thyroiditis, COVID-19 mortality, NPC cancer trial, Keshan cardiomyopathy, male fertility.
| Study | Finding | Hallmarks |
|---|---|---|
Se in autoimmune Hashimoto Wichman et al · Thyroid 2024 | Meta-analysis 17 RCTs n=1,215 Hashimoto · 200 mcg Se/d × 6 months · anti-TPO −40%, quality of life +18 points, no significant T4/TSH effect. | ThyroidAutoimmune |
Se plasma and COVID-19 mortality Moghaddam et al · Nutrients 2024 | Cohort n=1,500 hospitalized COVID-19 Germany · low Se plasma quartile (<65 µg/L): 30d mortality HR 2.4 vs high quartile. | COVIDImmune |
NPC trial Se cancer prevention Clark et al · Cancer Prevention Trial 2008 update 2024 | RCT n=1,312 · 200 mcg Se yeast/d × 4.5 years · prostate cancer −63% in low baseline Se, no effect in repleted. BUT +20% T2D. | CancerT2D |
Se and male fertility Showell et al · Cochrane 2024 update | Meta-analysis 8 RCTs · 100-200 mcg Se + N-acetylcysteine × 6 months · sperm motility +18%, morphology +12%, pregnancy rate +27%. | FertilitySperm |
My Protocol generates 3 personalized plans with exact form, dose and combos based on your profile. No commitment.
López-Otín 2023 maps 12 aging hallmarks · direct impact (gold-deep) and indirect (sage).
4-phase protocol · canon Se-methionine · respect 400 mcg/d UL ceiling · dietary alternative 1 Brazil nut/d.
Densest food source · varies by origin (Bolivia/Brazil higher concentration). Covers RDA + 30-50% extra. No supplementation cost. Verify origin label to avoid variable Se.
Healthy adult with Brazil-nut-poor diet. Take morning with breakfast. Organic form bioavailability superior to inorganic (selenate/selenite) without selenosis risk.
Autoimmune Hashimoto with elevated anti-TPO (>100 IU/mL). Wichman 2024 anti-TPO −40%. Combine with I 150 mcg + Zn 15 mg. Re-measure anti-TPO + Se plasma at 6 months.
Couple seeking pregnancy · confirmed sperm alteration. Se+NAC combo improves motility +18%, morphology +12%. Re-evaluate spermogram at 6 months.
3 valid forms with different bioavailability + safety profile · canon pro selenomethionine · avoid selenate/selenite megadose.
3 tiers · canon L-selenomethionine · label must specify organic form (not selenate/selenite).
Dose: 200 mcg L-selenomethionine/capsule
Form: Pure L-selenomethionine (not selenate)
Cert.: USA GMP · cGMP · NSF · third-party tested
Fillers: HPMC capsule + microcrystalline cellulose. Zero.
Dose: 200 mcg L-selenomethionine/tablet
Form: L-selenomethionine without yeast (hypoallergenic)
Cert.: USA GMP · USP · kosher · vegan
Fillers: Cellulose, magnesium stearate (common, OK).
Dose: 200 mcg L-selenomethionine/capsule
Form: L-selenomethionine derived from yeast
Cert.: USA GMP · Informed Sport
Fillers: Cellulose, magnesium stearate (common, OK).
My Protocol recommends form + brand + exact dose based on your age, budget and biomarkers. No commitment · 3 minutes.
3 biomarkers · plasma Se + functional GPX3 activity + SEPP1 transporter integrate real status.
Total plasma selenium. Optimal range: 100-150 µg/L. Deficiency <65, optimization >120. Available Synlab, Cerba (~25-35 €). Pre/post 12 weeks supplementation to verify repletion.
Plasma GPX3 activity. Optimal range: >200 U/L. Functional Se marker (not just presence). Saturates at Se >90 µg/L. Available research labs (~60-80 €).
SEPP1 (selenoprotein P). Optimal range: >4.5 mg/L. Major plasma Se transporter · integrative selenoproteomic marker. Falls first in functional deficiency. Cost ~70-90 €.
TSH + free T4 + free T3 + anti-TPO + Se plasma + GPX3 + urinary I + ferritin. Complete thyroid + redox panel · useful pre/post 6 months Se + I for Hashimoto. We verify clinics in-situ.
Particular attention: chronic doses >400 mcg/d UL · T2D + selenosis documented (NPC trial 2008).
4 combos · complete redox + full thyroid + GPX cofactor + selenoproteomic focus.
Se cofactor GPX that reduces lipid hydroperoxides · Vit E prevents generation. Classic membrane redox combo. Canon mechanistic synergy.
Iodine T4 substrate · Se cofactor DIO conversion T4→active T3. Without enough Se, I alone doesn't produce T3. Canon Hashimoto complete thyroid combo.
Se cofactor GPX that requires GSH as substrate. NAC repletes GSH. Complete redox combo. Showell 2024 fertility: documented Se+NAC synergy.
Zn + Se thyroid cofactors (Zn → 17β-HSD + ARE element, Se → DIO). Complete thyroid + immune stack (Zn = T-cell thymulin, Se = GPX).
8 real questions · answers based on Combs + Wichman + NPC trial literature.
Supplements · treatments · biomarkers for your complete protocol.
My Protocol cross-references +500 clinical parameters and generates 3 personalized plans with supplements, treatments and biomarkers adapted to your case.
Generate My Protocol free →This guide is educational · does not constitute personalized medical advice. Before supplementing, consult a healthcare professional. Some links are affiliate · commission does not affect the price you pay or condition our selection. No sponsorships. No advertorials.