Absorbable selenium capsules are dietary supplements providing 200 µg elemental selenium per capsule in the organic form L‑selenomethionine, designed for optimal uptake and stability in a softgel or vegetarian capsule matrix . Selenium is an essential trace element that functions as a cofactor in antioxidant enzymes (glutathione peroxidases) and thyroid hormone–converting deiodinases, supporting immune function, reproduction, and protection against oxidative stress . The organic selenomethionine form exhibits superior bioavailability, with absorption largely unaffected by baseline selenium status, making it preferable to inorganic forms like selenite or selenate .
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Composition & Formulation
Active Ingredient: 200 µg elemental selenium as L‑selenomethionine per capsule (Puritan’s Pride “Absorbable Selenium” softgel; NOW Foods 200 µg Veg Capsules) .
Excipients & Capsule: Softgel matrix (Puritan’s Pride) or hypromellose vegetarian capsule (NOW Foods) with inert fillers such as rice flour and cellulose .
Rationale for Form: L‑selenomethionine is incorporated nonspecifically into body proteins and into selenoprotein synthesis pathways, offering a reservoir effect and higher retention than inorganic salts .
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Biological Role & Mechanism
Selenium is integral to the 25 human selenoproteins, notably:
Glutathione Peroxidases (GPx): Catalyze reduction of hydrogen and lipid hydroperoxides, protecting cells from oxidative damage .
Iodothyronine Deiodinases: Activate (D1, D2) and deactivate (D3) thyroid hormones, essential for metabolic and neurological health .
Immune Modulation: Selenium status influences proliferation and function of T cells and NK cells, enhancing antiviral and antitumor immunity .
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Absorption & Bioavailability
High Absorption: Dietary selenium, especially as selenomethionine, is absorbed at rates of 85–95% and is minimally influenced by body stores .
Superior Form: L‑selenomethionine shows better retention and incorporation into body proteins compared with sodium selenite or selenate .
Peak Plasma Levels: Achieved within 1–2 hours post‑dose, with a half‑life reflecting both free amino acid pools and incorporation into tissue proteins .
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Indications & Uses
Dietary Supplementation: To meet or exceed the Recommended Dietary Allowance (RDA) of 55 µg/day in adults and address suboptimal intake from diet alone .
Antioxidant Support: Enhances cellular defenses against reactive oxygen species in conditions of increased oxidative stress (e.g., smoking, pollution) .
Thyroid Health: Adjunct for thyroid hormone metabolism in patients with marginal selenium status .
Immune Function: May support immune responsiveness, particularly in populations at risk of deficiency (elderly, HIV infection) .
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Dosage & Administration
Recommended Intake: Adults 19+ years: 55 µg/day (RDA); Tolerable Upper Intake Level (UL): 400 µg/day .
Supplement Regimen: 1 capsule (200 µg) once daily with a meal to enhance absorption of this fat‑soluble nutrient .
Special Populations: Pregnant/lactating women: RDA 60–70 µg/day; adjust supplement only under medical advice .
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Safety & Toxicity
Selenosis Risk: Chronic intake > UL (400 µg/day) can lead to garlic‑like breath odor, gastrointestinal upset, alopecia, nail brittleness, and neuropathy .
Acute Toxicity: Extremely high doses (> 1 000 µg/day) pose risk of severe GI distress, respiratory distress, and potentially fatal outcomes .
Monitoring: Patients on high‑dose regimens or with renal/hepatic impairment should have periodic plasma selenium levels and clinical assessment .
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Drug & Nutrient Interactions
Anticoagulants/Antiplatelets: Selenium may potentiate bleeding risk when combined with warfarin, heparin, aspirin, or clopidogrel; use with caution and monitor INR/bleeding .
Chemotherapeutics: May protect against cisplatin‑induced nephrotoxicity but potentially interfere with antitumor efficacy; consult oncology team .
Antioxidants: Synergistic with vitamin E; high combined doses can alter pharmacodynamics of lipid‑soluble drugs .
Heavy Metals: Selenium can mitigate mercury toxicity by forming inert complexes, but high supplemental selenium should be balanced against essential metal homeostasis .
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Storage & Packaging
Presentation: Bottles of 100–200 softgels or vegetarian capsules, typically amber‑colored to protect from light.
Storage Conditions: Store at 15–30 °C, in a dry place away from direct sunlight; keep container tightly closed and out of reach of children .
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References
1. Puritan’s Pride. Absorbable Selenium 200 mcg Softgels. Puritan.com.
2. NOW Foods. Selenium 200 mcg Veg Capsules. NOWFoods.com.
3. Office of Dietary Supplements (NIH). Selenium – Health Professional Fact Sheet. ODS.nih.gov.
4. Healthline. 10 Best Selenium Supplements. Healthline.com.
5. Wikipedia. Selenium. Wikipedia.org.
6. Wikipedia. Selenium in biology. Wikipedia.org.
7. NIH Office of Dietary Supplements. Selenium – Consumer Fact Sheet. ODS.nih.gov.
8. NCBI Bookshelf. Selenium – StatPearls. ncbi.nlm.nih.gov.
9. NCBI Bookshelf. Toxicological Profile for Selenium. ncbi.nlm.nih.gov.
10. Wikipedia. Selenium – Toxicity. Wikipedia.org.
11. Health.com
. 5 Health Benefits of Selenium. Health.com.
12. Lima Memorial Health System. Possible Interactions with Selenium. LimaMemorial.org.
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