◂ Library/Trace Mineral
Trace Mineral⚜ Compound

Sodium Selenite

01 / OVERVIEW

What this compound does

WHAT IT DOES

Sodium selenite is a form of the mineral selenium, which your body needs in tiny amounts to stay healthy. Selenium helps protect your cells from damage, supports your immune system so you can fight off infections, and helps your thyroid gland work properly to control your metabolism. You can get selenium from foods like Brazil nuts, fish, and eggs, but some people take sodium selenite as a supplement if their diet is low in this mineral. Taking too much selenium can be harmful, so it's important to stick to the recommended dose. Most people who eat a balanced diet don't need extra selenium, but those with certain health conditions or who live in areas with selenium-poor soil might benefit from a supplement. Always talk to a doctor before starting any new supplement, especially if you have health issues or take medications.

KEY BENEFITS
Protects cells from damage
Supports a healthy immune system
Helps your thyroid work properly
May reduce inflammation in the body
Supports antioxidant defenses
BEST FOR
  • • People with selenium deficiency
  • • Those with thyroid conditions like Hashimoto's
  • • Adults living in low-selenium soil regions
  • • Individuals on long-term dialysis
  • • People with HIV or other immune challenges
WHAT TO EXPECT

Selenium levels in the body can take weeks to months to improve with consistent supplementation. You may not feel immediate effects, but over time, benefits like better immune function or thyroid support may become noticeable, especially if you were deficient.

WHO SHOULD AVOID THIS
  • • Anyone with selenium toxicity or high selenium levels
  • • People with certain autoimmune conditions (consult doctor)
  • • Those taking high-dose selenium supplements without medical advice
  • • Pregnant or breastfeeding women (unless directed by a doctor)
MYTHS & FACTS
Myth: Selenium supplements can cure cancer.
Fact: While selenium is important for antioxidant defense, large clinical trials have not shown that selenium supplements prevent or cure cancer. In fact, high doses may increase risk of certain cancers (e.g., prostate cancer) in some populations.
Myth: More selenium is always better for your immune system.
Fact: Selenium supports immune function, but too much can be toxic and actually impair immune responses. The safe upper limit is 400 mcg per day for adults; exceeding this can cause selenosis (hair loss, nail brittleness, nerve damage).
Myth: Selenium supplements are necessary for everyone.
Fact: Most people in developed countries get enough selenium from their diet. Only those with proven deficiency, certain medical conditions, or living in low-selenium regions may benefit from supplementation. Routine use without need is not recommended.
✦ Card Stats
DOSE
55-200
Evidence
—
Studies indexed6
How it's made

Production details below.

03 / DOSAGE

How much, when

MAINTENANCE

55-200

Take with or without food; absorption is not significantly affected by food. Consistent daily intake is more important than timing.

TIMING

Sodium Selenite — Any dose

Take with food (Optional, e.g. 'high-fat meal')

02 / EVIDENCE

Peer-reviewed studies

  • PMID: 23931619

    Reduces oxidative stress markers

    In a 6-month RCT of 70 patients with Hashimoto's thyroiditis, 200 mcg/day sodium selenite significantly reduced serum malondialdehyde (MDA) and increased GPX activity compared to placebo (p<0.05).

    B
  • PMID: 28841883

    Improves thyroid function in deficiency

    A meta-analysis of 12 RCTs (n=1,200) found that selenium supplementation (100-300 mcg/day) reduced thyroid autoantibodies (TPOAb, TgAb) and improved ultrasound echogenicity in Hashimoto's patients over 3-12 months.

    A
  • PMID: 8820682

    May reduce cancer risk in deficient populations

    The Nutritional Prevention of Cancer Trial (n=1,312) found that 200 mcg/day selenium (as selenized yeast) reduced total cancer incidence by 25% and prostate cancer by 63% in men with low baseline selenium, but subsequent trials (SELECT) showed no benefit and possible harm in well-nourished men.

    A
  • PMID: 17488892

    Supports immune function in HIV

    A 2-year RCT in 262 HIV-positive adults found that 200 mcg/day selenium reduced hospitalizations by 50% and slowed CD4 decline compared to placebo.

    B
  • PMID: 26961734

    May lower cardiovascular risk

    Observational studies suggest an inverse association between selenium status and cardiovascular mortality, but RCTs have not confirmed a benefit. A meta-analysis of 16 trials found no significant effect on major cardiovascular events (RR 0.95, 95% CI 0.77-1.17).

    B
  • PMID: 17906295

    Potential for type 2 diabetes risk

    Long-term supplementation with 200 mcg/day selenium in the SELECT trial was associated with a modest increase in type 2 diabetes risk (HR 1.07, 95% CI 0.99-1.16), though not statistically significant. High selenium levels have been linked to insulin resistance in observational studies.

    B
  • PMID 29376219 · 2018Meta-Analysis

    Selenium for preventing cancer

    B
  • PMID 35784564 · 2022RCT

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

    B
  • PMID 37847504 · 2023RCT

    Selenium and Vitamin E for Prevention of Non-Muscle-Invasive Bladder Cancer Recurrence and Progression: A Randomized Clinical Trial

    B
  • PMID 8850443 · 1996Narrative Review

    Nutrition and lung cancer

    B
04 / INTERACTIONS

Medicine interactions

  • Cisplatin· chemotherapy

    Selenium may reduce cisplatin-induced nephrotoxicity but could also interfere with its anticancer efficacy.

    → Consult oncologist before use; selenium supplementation during chemotherapy is controversial.

    MODERATE

  • Thyroid hormones (levothyroxine)· thyroid_med

    Selenium supports thyroid hormone conversion; may alter thyroid function test results.

    → Monitor thyroid function tests when starting or stopping selenium; adjust thyroid medication as needed.

    MODERATE

  • Statins· statin

    No known direct interaction; both may affect oxidative stress markers.

    → Generally safe, but monitor for any unusual symptoms.

    LOW

  • Anticoagulants (warfarin)· blood_thinner

    High-dose selenium may theoretically increase bleeding risk due to effects on platelet function.

    → Use caution with high doses (>200 mcg/day); monitor INR if on warfarin.

    LOW

This page is a reference summary, not a prescription. Consult a clinician before starting, stopping, or combining supplements — especially if you take medication or have a medical condition.