NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated July 13, 2026

Selenium

Mineral ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

Essential trace mineral crucial for thyroid function, antioxidant defense, and immune health. Narrow therapeutic window, both deficiency and excess are harmful.

Evidence tier
Strong
Indexed sources
20 2007–2024
Interactions
0
Cost / month
$0.90 budget
Read the sources → Compare profiles
Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

Selenium is a mineral most often used for thyroid function, antioxidant defense, immune support. NutriStack rates the overall evidence as strong. A typical adult dose is 100–200 mcg daily, commonly taken as selenomethionine (organic form, better retention). This profile indexes 20 sources.

What it's good for
  • Thyroid function1,10
  • Antioxidant defense19
  • Immune support4
  • DNA protection
  • Fertility8
What to watch for
  • Selenosis at high doses (garlic breath, hair loss, nail brittleness)
  • Nausea
  • Do not exceed 400mcg daily
  • Consult doctor for autoimmune conditions (may benefit autoimmune thyroiditis but requires monitoring)10,12

The bottom line

Evidence rating strong. Most-documented uses: thyroid function, antioxidant defense, immune support. 20 sources indexed (2007–2024), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Incorporated as selenocysteine into 25 selenoproteins including glutathione peroxidases (GPx, neutralize hydrogen peroxide), thioredoxin reductases (regenerate antioxidants), and iodothyronine deiodinases (convert T4 to active T3 thyroid hormone).18,19

Class
Trace Mineral
Found in food
Brazil nuts, Tuna, Sardines
Low-status signs
Thyroid dysfunction, Weakened immunity
Absorption
Water-soluble; take with food
Dosing

Dosing & protocol.

Common range
100–200 mcg daily
Recommended form
Selenomethionine (organic form, better retention)

Do not exceed 400mcg/day; Brazil nuts are the richest food source (1-2 nuts = daily need)15,1

Cost

What it actually costs.

Real-world pricing across three quality tiers. Assumes L-Selenomethionine.

BudgetBest value
$0.90 /mo
$0.03 per dose
Mid
$2.10 /mo
$0.07 per dose
Premium
$4.50 /mo
$0.15 per dose

Assumes about 100-200 mcg/day. Selenium remains inexpensive, but unnecessary high-dose long-term use carries real toxicity risk. Updated 2026-04-02.

From food

The same dose, as food.

How much you'd eat to match a supplemental dose.

100 mcg selenium
About 2 Brazil nuts

Brazil nuts vary wildly in selenium content, so they can overshoot easily.

200 mcg selenium
About 3-4 Brazil nuts

Daily high intake from nuts plus supplements can become excessive.

Safety

Full safety detail.

Side effects

  • Selenosis at high doses (garlic breath, hair loss, nail brittleness)
  • Nausea

Contraindications

  • Do not exceed 400mcg daily
  • Consult doctor for autoimmune conditions (may benefit autoimmune thyroiditis but requires monitoring)10,12
Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Meta-analyses & systematic reviews

14

Randomized controlled trials

2
  • 15Low-dose selenium supplementation in the elderly: effects on thyroid function, immunity, and quality of lifeRayman MP, Thompson AJ, Bekaert B et al. · Clin Endocrinol · 2008
  • 16Selenium supplementation and HIV progression: a randomized controlled trialBaum MK, Campa A, Lai S et al. · Arch Intern Med · 2007

Reviews & position papers

3

Reference material

1
FAQ

Common questions.

Quick answers about Selenium, drawn from the data on this page.

What is Selenium?

Essential trace mineral crucial for thyroid function, antioxidant defense, and immune health. Narrow therapeutic window, both deficiency and excess are harmful.

What is Selenium used for?

Commonly cited benefits of Selenium include: Thyroid function; Antioxidant defense; Immune support; DNA protection; Fertility. NutriStack rates the overall evidence as strong.

What is a typical dose of Selenium?

A typical adult dose of Selenium is 100–200 mcg daily. The commonly recommended form is Selenomethionine (organic form, better retention). These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Selenium?

Reported side effects include selenosis at high doses (garlic breath, hair loss, nail brittleness), nausea. This is educational information; check with a healthcare professional before use.

How strong is the evidence for Selenium?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

Selenium in NutriStack.

Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.

Download on the App Store → Read the methodology

NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.