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    Supplement

    SeleniumNew

    Supplement
    Minerals
    4/10 Evidence

    An essential trace mineral incorporated into selenoproteins (glutathione peroxidases, thioredoxin reductases, iodothyronine deiodinases) that support antioxidant defense and thyroid hormone activation. Benefit is concentrated in people with low selenium status; supplementing replete adults has not shown clear benefit and may carry risk.

    Mechanism of Action

    Selenium is inserted as selenocysteine into about 25 human selenoproteins. Glutathione peroxidases and thioredoxin reductases neutralize peroxides and maintain redox balance; iodothyronine deiodinases convert thyroxine (T4) to active triiodothyronine (T3). Intake-response is U-shaped: deficiency impairs selenoprotein function, while chronic excess is toxic.

    Dosing Protocol

    Recommended

    100mcg per day (Tolerable Upper Intake Level: 400 mcg/day from all sources)

    Standard starting dose based on research

    Therapeutic Range

    55

    Minimum

    to

    200

    Maximum

    mcg per day (Tolerable Upper Intake Level: 400 mcg/day from all sources)

    With a meal; split doses are not required

    Cycling Protocol

    No fixed cycling; consider testing baseline status (serum or whole-blood selenium) and re-testing after 3-6 months rather than taking it indefinitely

    Dosages are general guidelines. Individual requirements vary based on body weight, health status, and specific goals. Start with lower doses and adjust based on response.

    Benefits

    Primary Benefits

    • Corrects low selenium status and supports selenoprotein antioxidant activity
    • Supports thyroid hormone metabolism, particularly in autoimmune thyroiditis with low selenium
    • Supports immune function

    Secondary Benefits

    Possible reduction in thyroid peroxidase antibodies in Hashimoto thyroiditis (small trials, inconsistent)
    Possible support for sperm quality in subfertile men with low status

    Safety Information

    Contraindications

    Do not use if any of the following apply:

    • •Intake above 400 mcg/day (risk of selenosis)
    • •Replete selenium status or high-selenium regions (e.g. Brazil nut daily intake plus supplement)
    • •Insulin resistance or type 2 diabetes — use only if status is low and under clinician guidance
    • •Pregnancy and breastfeeding above recommended intake

    Drug/Supplement Interactions

    May interact with the following. Consult a healthcare provider before combining:

    Anticoagulants (warfarin) — high doses may alter INR
    Cisplatin and other chemotherapy — discuss with oncology team
    Sodium selenite may reduce absorption when taken with high-dose vitamin C
    Statin and niacin combination — theoretical antagonism, evidence limited

    Potential Side Effects

    Some users may experience:

    Garlic-like breath odor and metallic taste
    Hair and nail brittleness or loss (selenosis)
    Nausea, diarrhea, fatigue at high doses
    Possible rise in glucose or type 2 diabetes risk with long-term supplementation in replete adults

    This is not a complete list of interactions or side effects. Individual responses vary. Always start with the lowest effective dose and monitor your response. Report any adverse effects to your healthcare provider.

    Quality Markers

    Look for these specific quality indicators when sourcing this compound:

    • Selenomethionine or selenium-enriched yeast generally better retained than sodium selenite
    • Label states mcg of elemental selenium, not mg of compound
    • Third-party tested for accurate dosing

    Trusted Certifications

    NSF Certified
    USP Verified
    GMP Certified
    ConsumerLab Approved

    Note: Supplement quality varies dramatically between brands. Cheap supplements often contain fillers, incorrect doses, or contaminants. Investing in quality products from reputable manufacturers is essential for safety and efficacy.

    Evidence Profile

    Evidence Score

    4/10

    Emerging/Anecdotal

    Limited clinical data, primarily mechanistic studies or user reports

    Classification:
    Emerging/Moderate — benefit is status-dependent. A 2023 umbrella review of meta-analyses linked higher selenium intake with lower all-cause mortality and some cancers in observational data, but most included supplementation evidence was low quality and the authors did not recommend extra selenium for the general population. Randomized trials in replete populations (e.g. SELECT, prostate cancer prevention) showed no benefit, and a 2018 meta-analysis reported an 11% higher type 2 diabetes risk with supplementation (RR 1.11, 95% CI 1.01-1.22), although a second 2018 review did not find a significant increase. Evidence is strongest for correcting deficiency; scored Emerging/Moderate (4). Evidence

    Evidence Scale

    8-10

    Strong

    5-7

    Moderate

    1-4

    Emerging

    PHS
    671
    / 1000
    T3
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