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Selenium
The Bottom Line
Selenium is an essential trace mineral that the body needs in small amounts.
- Evidence grade
- Clinical research qualityB
- Category
- Vitamins & Minerals
- Best form
- selenomethionine (organic, best absorbed)
- Effective dose
- 55-200 mcg daily
- Lab tested
- 7 of 10 products
- Category
- Vitamins & Minerals
- Best form
- selenomethionine (organic, best absorbed)
- Effective dose
- 55-200 mcg daily
- Lab tested
- 7 of 10 products
What Is Selenium?
Selenium is an essential trace mineral that the body needs in small amounts. It is a required component of 25 selenoproteins, including glutathione peroxidase (antioxidant defense) and the deiodinase enzymes that convert thyroid hormone T4 to the active T3 form. Most adults in the US and Europe get adequate selenium from diet - Brazil nuts, seafood, organ meats, and grains grown in selenium-rich soil are reliable sources.
The most heavily marketed claim - cancer prevention - took a devastating hit. The largest and most rigorous trial (over 35,000 men) found selenium supplementation did NOT reduce prostate cancer risk. A follow-up analysis actually found a significant increase in high-grade prostate cancer in men who already had adequate selenium levels. An earlier, smaller trial had suggested benefit, but it was never replicated. The cancer prevention story for selenium is effectively dead in well-nourished populations.
Where selenium has real utility is thyroid health. Multiple trials in patients with Hashimoto's thyroiditis show that 200mcg/day significantly reduces thyroid antibody levels. Reviews confirm this effect, though whether it translates to fewer patients progressing to full hypothyroidism remains unclear. Selenium is a reasonable adjunct for Hashimoto's patients, particularly those with low selenium levels.
The critical context here is the U-shaped dose-response curve. Selenium supplementation benefits people who are deficient, but supplementing above adequate status appears to cause harm. SELECT's diabetes signal (a non-significant trend toward increased type 2 diabetes risk with selenium supplementation) was concerning and consistent with observational data showing a positive association between high selenium status and diabetes prevalence. The takeaway: if you eat a varied diet in North America, you probably do not need supplemental selenium, and taking it "just in case" is not harmless. If you have Hashimoto's or live in a selenium-poor region (parts of China, parts of Europe), it may be worth discussing with your doctor.
Selenomethionine is the preferred form - it is incorporated into body proteins in place of methionine, creating a selenium reserve. Sodium selenite is cheaper but less bioavailable and not stored the same way. Selenium yeast contains a mix of organic selenium compounds, predominantly selenomethionine, and is also well absorbed.
Does It Work? The Evidence
Thyroid function and Hashimoto's antibody reduction
SupportedWichman et al. Thyroid 2016 meta-analysis; Cochrane review 2010; multiple RCTs showing TPO antibody reduction at 200 mcg/day
Prostate cancer prevention
IneffectiveSELECT trial (JAMA 2009, n=35,533) - no benefit; follow-up JNCI 2014 - possible harm in selenium-replete men. Clark et al. JAMA 1996 - positive but not replicated.
General cancer prevention
Not There YetNPC trial (Clark et al. 1996) - secondary endpoint positive; SELECT - negative; Cochrane 2018 review of selenium for cancer - insufficient evidence
Antioxidant defense and immune function
SupportedSelenoproteins (glutathione peroxidase, thioredoxin reductase) are well-characterized antioxidant enzymes; clinical benefits seen primarily in deficient populations
Cardiovascular disease prevention
Not There YetObservational studies show mixed results; Cochrane 2013 review found no clear evidence for CVD prevention from selenium supplementation
Cognitive function preservation
Not There YetSmall observational studies link low selenium to cognitive decline; no large RCTs support supplementation for cognition
| Claimed Benefit | Evidence Level | Key Studies | Our Verdict |
|---|---|---|---|
| Thyroid function and Hashimoto's antibody reduction | Moderate | Wichman et al. Thyroid 2016 meta-analysis; Cochrane review 2010; multiple RCTs showing TPO antibody reduction at 200 mcg/day | Supported |
| Prostate cancer prevention | Strong | SELECT trial (JAMA 2009, n=35,533) - no benefit; follow-up JNCI 2014 - possible harm in selenium-replete men. Clark et al. JAMA 1996 - positive but not replicated. | Ineffective |
| General cancer prevention | Limited | NPC trial (Clark et al. 1996) - secondary endpoint positive; SELECT - negative; Cochrane 2018 review of selenium for cancer - insufficient evidence | Not There Yet |
| Antioxidant defense and immune function | Moderate | Selenoproteins (glutathione peroxidase, thioredoxin reductase) are well-characterized antioxidant enzymes; clinical benefits seen primarily in deficient populations | Supported |
| Cardiovascular disease prevention | Limited | Observational studies show mixed results; Cochrane 2013 review found no clear evidence for CVD prevention from selenium supplementation | Not There Yet |
| Cognitive function preservation | Weak | Small observational studies link low selenium to cognitive decline; no large RCTs support supplementation for cognition | Not There Yet |
How to Choose: Forms, Doses & What Matters
Clinical dose: 55-200 mcg daily; RDA is 55 mcg for adults, upper tolerable limit is 400 mcg/day
Best forms: selenomethionine (organic, best absorbed), selenium yeast (mixed organic forms), sodium selenite (inorganic, lower bioavailability)
Take with food for best absorption. Selenomethionine can be taken with or without food, but taking it with a meal reduces the chance of GI upset. Do not exceed 200 mcg/day from supplements without medical supervision - the RDA is only 55 mcg, and most people get 100-150 mcg from diet alone in North America. If supplementing for thyroid support, 200 mcg/day of selenomethionine is the dose used in most Hashimoto's RCTs. Do not take selenium at the same time as high-dose vitamin C (above 500 mg), as in vitro studies suggest vitamin C may reduce selenite absorption - though this interaction is less relevant for selenomethionine. Pairing with adequate iodine intake is important for thyroid function, as selenium and iodine work together in thyroid hormone metabolism.
Who Should Take Selenium?
People with documented selenium deficiency or insufficiency (serum selenium below 70 mcg/L). Patients with Hashimoto's thyroiditis, where multiple RCTs support 200 mcg/day for reducing TPO antibodies - discuss with your endocrinologist. Those living in selenium-poor regions (parts of China, Finland, New Zealand, and some areas of Europe where soil selenium is low). People with malabsorptive conditions (Crohn's disease, celiac disease, short bowel syndrome) who may not absorb adequate selenium from food. Individuals on long-term parenteral nutrition without selenium supplementation.
Who Should Avoid It?
People with adequate or high selenium status - the U-shaped dose-response curve means supplementing above adequate levels may increase risk of type 2 diabetes (SELECT trial signal) and potentially high-grade prostate cancer (JNCI 2014 analysis). Anyone taking more than 400 mcg/day total from food and supplements risks selenosis (selenium toxicity). People on anticoagulant medications should exercise caution as selenium may have additive anticoagulant effects. Those undergoing chemotherapy should consult their oncologist, as selenium's antioxidant activity could theoretically interfere with oxidative treatments.
Side Effects & Safety
Well tolerated at doses up to 200 mcg/day. The upper tolerable intake level is 400 mcg/day (total from food and supplements). Chronic intake above 400 mcg/day can cause selenosis, characterized by garlic breath odor, hair loss, brittle nails, skin rashes, nausea, diarrhea, and fatigue. Acute toxicity from very high doses (above 1,000 mcg) can cause more severe symptoms including neurological damage. Long-term supplementation at 200 mcg/day in selenium-replete individuals was associated with a non-significant trend toward increased type 2 diabetes risk in the SELECT trial - this finding was not statistically significant but is biologically plausible and worth noting. Brazil nuts are the richest dietary source (68-91 mcg per nut) - eating more than 3-4 daily could push intake above safe levels.
Product Scores
10 products scored on evidence quality, third-party testing, cost per effective dose, and ingredient transparency.
The Scorecard: 10 Products Compared
Nature Made Selenium 200 mcg
Nature MadeUSP Verified at bottom-tier pricing. The obvious default choice for anyone who actually needs selenium supplementation.
200 mcg selenomethionine - matches dose used in thyroid RCTs. Evidence for general supplementation in replete populations is weak, but dosing is clinically appropriate.
USP Verified - independently tested for purity, potency, and disintegration. This is the gold standard for third-party certification in this category.
$0.04/day at 200 mcg - among the cheapest selenium options per effective dose
Full ingredient disclosure, selenomethionine form clearly specified, USP seal displayed, no proprietary blends
200 mcg selenomethionine - matches dose used in thyroid RCTs. Evidence for general supplementation in replete populations is weak, but dosing is clinically appropriate.
USP Verified - independently tested for purity, potency, and disintegration. This is the gold standard for third-party certification in this category.
$0.04/day at 200 mcg - among the cheapest selenium options per effective dose
Full ingredient disclosure, selenomethionine form clearly specified, USP seal displayed, no proprietary blends
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Thorne Selenomethionine 200 mcg
ThorneNSF Certified for Sport makes this the clear choice for competitive athletes who undergo drug testing.
200 mcg selenomethionine - standard clinical dose, appropriate form
NSF Certified for Sport - tested for 270+ banned substances. Thorne exceeds FDA cGMP standards. Trusted by professional sports organizations.
$0.20/day - premium pricing. The NSF Certified for Sport status adds real value for competitive athletes who need substance testing assurance.
Clean label with full disclosure. Selenomethionine form specified. Minimal excipients. No proprietary blends.
200 mcg selenomethionine - standard clinical dose, appropriate form
NSF Certified for Sport - tested for 270+ banned substances. Thorne exceeds FDA cGMP standards. Trusted by professional sports organizations.
$0.20/day - premium pricing. The NSF Certified for Sport status adds real value for competitive athletes who need substance testing assurance.
Clean label with full disclosure. Selenomethionine form specified. Minimal excipients. No proprietary blends.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
NOW Foods Selenium 200 mcg
NOW FoodsBest cost-per-dose in the category from a reputable manufacturer. Selenium yeast form is well-studied and well-absorbed.
200 mcg from selenium yeast - a mix of organic selenium compounds, predominantly selenomethionine. Comparable to pure selenomethionine in clinical studies.
NOW Foods is NPA GMP audited. No USP or NSF certification on this specific product. Has passed some ConsumerLab testing rounds.
$0.03/day - the cheapest option in this comparison. 180-count veg capsule bottle.
Good disclosure. Form specified as selenium yeast. Vegan capsule. No proprietary blends. Source not specified as granularly as some competitors.
200 mcg from selenium yeast - a mix of organic selenium compounds, predominantly selenomethionine. Comparable to pure selenomethionine in clinical studies.
NOW Foods is NPA GMP audited. No USP or NSF certification on this specific product. Has passed some ConsumerLab testing rounds.
$0.03/day - the cheapest option in this comparison. 180-count veg capsule bottle.
Good disclosure. Form specified as selenium yeast. Vegan capsule. No proprietary blends. Source not specified as granularly as some competitors.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Doctor's Best Selenium 200 mcg
Doctor's BestUses a branded selenomethionine ingredient. Good value for the preferred form, but lacks the independent certification that separates B-tier from A-tier.
200 mcg as SeLECT selenomethionine (branded form). Appropriate dose and form.
GMP certified. Third-party tested per brand claims. No major independent certification (USP, NSF, ConsumerLab) visible.
$0.05/day - good value. 180-count bottle at competitive pricing.
Form specified as SeLECT branded selenomethionine. No proprietary blends. Full ingredient list disclosed.
200 mcg as SeLECT selenomethionine (branded form). Appropriate dose and form.
GMP certified. Third-party tested per brand claims. No major independent certification (USP, NSF, ConsumerLab) visible.
$0.05/day - good value. 180-count bottle at competitive pricing.
Form specified as SeLECT branded selenomethionine. No proprietary blends. Full ingredient list disclosed.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Life Extension Super Selenium Complex 200 mcg
Life ExtensionMulti-form selenium approach is theoretically interesting but lacks comparative RCT data vs. selenomethionine alone. Added vitamin E is a small dose.
200 mcg from a blend of three selenium forms (selenomethionine, sodium selenite, selenium-methylselenocysteine) plus added vitamin E. Multi-form approach lacks strong comparative clinical data.
Life Extension uses third-party testing (certificates available on request). GMP facility. No USP or NSF certification on this product.
$0.08/day - mid-range pricing. Added vitamin E and multi-form blend account for slight premium.
Good disclosure. Each selenium form and amount is individually listed. Added vitamin E (as alpha-tocopherol) amount specified. No proprietary blends.
200 mcg from a blend of three selenium forms (selenomethionine, sodium selenite, selenium-methylselenocysteine) plus added vitamin E. Multi-form approach lacks strong comparative clinical data.
Life Extension uses third-party testing (certificates available on request). GMP facility. No USP or NSF certification on this product.
$0.08/day - mid-range pricing. Added vitamin E and multi-form blend account for slight premium.
Good disclosure. Each selenium form and amount is individually listed. Added vitamin E (as alpha-tocopherol) amount specified. No proprietary blends.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Pure Encapsulations Selenium (selenomethionine) 200 mcg
Pure EncapsulationsThe cleanest formulation on this list. Best option for people with multiple food sensitivities or autoimmune conditions requiring minimal excipients.
200 mcg selenomethionine - appropriate clinical dose from a practitioner-grade brand
Third-party tested by Eurofins/Silliker. Hypoallergenic - free from gluten, dairy, soy, and major allergens. GMP+ quality system.
$0.17/day - significant premium over Nature Made for the same active ingredient. Justified only if you need the allergen-free formulation.
Exemplary transparency. Every ingredient fully disclosed. No unnecessary fillers or additives. Hypoallergenic capsule shell.
200 mcg selenomethionine - appropriate clinical dose from a practitioner-grade brand
Third-party tested by Eurofins/Silliker. Hypoallergenic - free from gluten, dairy, soy, and major allergens. GMP+ quality system.
$0.17/day - significant premium over Nature Made for the same active ingredient. Justified only if you need the allergen-free formulation.
Exemplary transparency. Every ingredient fully disclosed. No unnecessary fillers or additives. Hypoallergenic capsule shell.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Nutricost Selenium 200 mcg
NutricostBudget-tier pricing with the right form and dose, but the absence of independent testing certification is a real issue for a trace mineral where the therapeutic dose and the toxic dose are not far apart.
200 mcg selenomethionine - correct dose and preferred form
Manufactured in a GMP-compliant, FDA-registered facility. Claims third-party testing but does not display any recognized certification (USP, NSF, ConsumerLab, BSCG). For a YMYL supplement with a narrow safety margin, unverified quality is a bigger concern than usual.
$0.03/day - among the cheapest options available. 240-count bottle.
Form specified. No proprietary blends. Ingredient list is clean and simple. Brand provides less supporting documentation than premium competitors.
200 mcg selenomethionine - correct dose and preferred form
Manufactured in a GMP-compliant, FDA-registered facility. Claims third-party testing but does not display any recognized certification (USP, NSF, ConsumerLab, BSCG). For a YMYL supplement with a narrow safety margin, unverified quality is a bigger concern than usual.
$0.03/day - among the cheapest options available. 240-count bottle.
Form specified. No proprietary blends. Ingredient list is clean and simple. Brand provides less supporting documentation than premium competitors.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Solgar Selenium 200 mcg
SolgarUses sodium selenate rather than selenomethionine. Not the preferred form based on clinical literature. Priced above competitors offering the better form.
200 mcg as sodium selenate (inorganic form). Most thyroid RCTs used selenomethionine, not selenate. Sodium selenate is absorbed but metabolized differently.
Solgar follows GMP standards. Third-party tested per brand claims, but no USP, NSF, or ConsumerLab certification visible on this product.
$0.11/day - above median pricing for an inorganic selenium form, which is less desirable than selenomethionine
Full ingredient list provided. Form specified as sodium selenate. No proprietary blends. Glass bottle packaging.
200 mcg as sodium selenate (inorganic form). Most thyroid RCTs used selenomethionine, not selenate. Sodium selenate is absorbed but metabolized differently.
Solgar follows GMP standards. Third-party tested per brand claims, but no USP, NSF, or ConsumerLab certification visible on this product.
$0.11/day - above median pricing for an inorganic selenium form, which is less desirable than selenomethionine
Full ingredient list provided. Form specified as sodium selenate. No proprietary blends. Glass bottle packaging.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Bronson Selenium 200 mcg
Bronson
Inferior form (sodium selenite) with no independent testing. The low price reflects the low-cost raw material, not smart formulation. You can get selenomethionine from NOW Foods for the same price.
200 mcg as sodium selenite - inorganic form with lower bioavailability than selenomethionine. Not the form used in most positive thyroid RCTs.
GMP facility. No third-party testing certification visible. Sodium selenite is a less expensive raw material but also less desirable.
$0.04/day - cheap, but you are paying for an inferior form. Cost per effective absorbed dose is less favorable than the sticker price suggests.
Form specified as sodium selenite. Basic ingredient list. No proprietary blends. Limited supporting information on sourcing or testing.
200 mcg as sodium selenite - inorganic form with lower bioavailability than selenomethionine. Not the form used in most positive thyroid RCTs.
GMP facility. No third-party testing certification visible. Sodium selenite is a less expensive raw material but also less desirable.
$0.04/day - cheap, but you are paying for an inferior form. Cost per effective absorbed dose is less favorable than the sticker price suggests.
Form specified as sodium selenite. Basic ingredient list. No proprietary blends. Limited supporting information on sourcing or testing.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Amazon Elements Selenium 200 mcg
Amazon Elements
Inferior selenium form, no recognized third-party certification, and Amazon's private-label supplements have a spotty track record. The QR code transparency feature is marketing, not quality assurance.
200 mcg as sodium selenite - inorganic form. Correct dose but not the preferred form for clinical applications.
Claims third-party testing with results viewable via QR code on label. However, no recognized independent certification (USP, NSF, ConsumerLab). Amazon's in-house brand has faced criticism for supplement quality control in the past.
$0.05/day - reasonable price, but the sodium selenite form means your effective absorbed dose is lower than what the label implies
QR code links to a certificate of analysis - a nice idea in theory, but the testing is not by a recognized independent body. Sodium selenite form specified. No proprietary blends. Overall, the transparency theater (QR codes, 'traceable to origin' language) looks better than it performs.
200 mcg as sodium selenite - inorganic form. Correct dose but not the preferred form for clinical applications.
Claims third-party testing with results viewable via QR code on label. However, no recognized independent certification (USP, NSF, ConsumerLab). Amazon's in-house brand has faced criticism for supplement quality control in the past.
$0.05/day - reasonable price, but the sodium selenite form means your effective absorbed dose is lower than what the label implies
QR code links to a certificate of analysis - a nice idea in theory, but the testing is not by a recognized independent body. Sodium selenite form specified. No proprietary blends. Overall, the transparency theater (QR codes, 'traceable to origin' language) looks better than it performs.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Nature Made Selenium 200 mcg Nature Made | Thorne Selenomethionine 200 mcg Thorne | NOW Foods Selenium 200 mcg NOW Foods | Doctor's Best Selenium 200 mcg Doctor's Best | Life Extension Super Selenium Complex 200 mcg Life Extension | Pure Encapsulations Selenium (selenomethionine) 200 mcg Pure Encapsulations | Nutricost Selenium 200 mcg Nutricost | Solgar Selenium 200 mcg Solgar | Bronson Selenium 200 mcg Bronson | Amazon Elements Selenium 200 mcg Amazon Elements |
|---|---|---|---|---|---|---|---|---|---|---|
| Overall | A- | A- | B+ | B+ | B+ | B+ | B | B | B- | B- |
| Evidence | B | B | B | B | B | B | B | B | B | B |
| Quality & Purity | A+ | A+ | B | B | B+ | A | C+ | B | C | C- |
| Value | A | B- | A | A- | B | C+ | A | B- | A- | B+ |
| Transparency | A | A | B+ | B+ | B+ | A+ | B | B | C+ | C |
| Cost/Day | $0.04 | $0.20 | $0.04 | $0.05 | $0.08 | $0.17 | $0.03Winner | $0.11 | $0.04 | $0.05 |
| Dose/Serving | 200mcg | 200mcg | 200mcg | 200mcg | 200mcg | 200mcg | 200mcg | 200mcg | 200mcg | 200mcg |
| Form | selenomethionine tablet | selenomethionine capsule | selenium yeast veg capsule | selenomethionine (SeLECT branded) veg capsule | selenomethionine + sodium selenite + Se-methylselenocysteine blend, capsule | selenomethionine hypoallergenic capsule | selenomethionine capsule | sodium selenate tablet | sodium selenite tablet | sodium selenite capsule |
| Third-Party Tested | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | No | ✓ Yes | No | No |
| Proprietary Blend | No | No | No | No | No | No | No | No | No | No |
Frequently Asked Questions
Do I need a selenium supplement if I eat a normal diet?
Probably not. The average American diet provides about 100-150 mcg of selenium per day, which is well above the 55 mcg RDA. Selenium is found in Brazil nuts (one nut provides 68-91 mcg), seafood, organ meats, poultry, eggs, and grains. Deficiency is rare in North America but more common in parts of China, Russia, and Europe where soil selenium is low. A blood test measuring serum selenium can confirm your status if you are concerned.
What happened with selenium and cancer prevention?
The cancer story collapsed with the SELECT trial. An earlier study (Clark et al. 1996, n=1,312) found that selenium supplementation appeared to reduce prostate cancer incidence by about 50% - but that was a secondary endpoint, not what the study was designed to test. SELECT (JAMA 2009, n=35,533) was a massive, well-designed trial specifically built to test this claim. It found no reduction in prostate cancer with 200 mcg/day selenomethionine. A follow-up analysis found selenium may actually increase high-grade prostate cancer risk in men who already had adequate selenium levels. This is a case study in why secondary endpoints need replication.
Is selenomethionine better than sodium selenite?
Yes, for most supplementation purposes. Selenomethionine is an organic form that is approximately 90% absorbed and is incorporated into body proteins as a selenium reserve. Sodium selenite is an inorganic form with lower bioavailability (about 50% absorbed) and is not stored in proteins the same way. Most clinical trials showing benefits in Hashimoto's patients used selenomethionine. Selenium yeast (which contains mostly selenomethionine) is also a good option. The one exception: some researchers argue selenite may be preferable for acute antioxidant effects because it is not sequestered in proteins, but the clinical evidence for this distinction is thin.
Can selenium help with thyroid problems?
For Hashimoto's thyroiditis specifically, yes - with caveats. Multiple RCTs have shown that 200 mcg/day of selenomethionine reduces TPO (thyroid peroxidase) antibody levels in Hashimoto's patients, typically by 20-40% over 3-12 months. However, it remains unclear whether this antibody reduction translates to meaningful clinical outcomes like preventing progression to overt hypothyroidism. Selenium is also required for the deiodinase enzymes that convert T4 to active T3. For general thyroid support, ensuring adequate selenium intake through diet is sensible - supplementation is most justified when deficiency is documented or in autoimmune thyroid disease.
What are the signs of selenium deficiency?
Mild deficiency may not cause obvious symptoms. More significant deficiency can cause fatigue, brain fog, weakened immune function, hair loss, and thyroid dysfunction. Severe deficiency is rare in developed countries but can cause Keshan disease (a cardiomyopathy first identified in selenium-poor regions of China) and Kashin-Beck disease (an osteoarthropathy). Risk factors include living in selenium-poor regions, malabsorptive conditions (Crohn's, celiac), chronic kidney disease requiring dialysis, and HIV infection.
Can I just eat Brazil nuts instead of taking a supplement?
Yes, and for most people this is the better approach. A single Brazil nut contains roughly 68-91 mcg of selenium, so 1-2 nuts per day can easily meet the 55 mcg RDA and push into the 100-200 mcg range used in clinical trials. This is cheaper than any supplement and comes with healthy fats and other minerals. The caveat: selenium content in Brazil nuts varies significantly depending on the soil where the trees grew, so dosing is less precise than a supplement. Do not eat more than 3-4 Brazil nuts daily on a regular basis - it is surprisingly easy to exceed the 400 mcg upper limit with this food.
Sources
- Lippman SM, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51.
- Clark LC, et al. Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial (NPC trial). JAMA. 1996;276(24):1957-1963.
- Kristal AR, et al. Baseline selenium status and effects of selenium and vitamin E supplementation on prostate cancer risk. J Natl Cancer Inst. 2014;106(3):djt456.
- Wichman J, et al. Selenium supplementation significantly reduces thyroid autoantibody levels in patients with chronic autoimmune thyroiditis: a systematic review and meta-analysis. Thyroid. 2016;26(12):1681-1692.
- NIH Office of Dietary Supplements. Selenium Fact Sheet for Health Professionals. Updated 2024.
- Vinceti M, et al. Selenium for preventing cancer. Cochrane Database Syst Rev. 2018;1(1):CD005195.
- Rayman MP. Selenium and human health. Lancet. 2012;379(9822):1256-1268.
- Stranges S, et al. Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial. Ann Intern Med. 2007;147(4):217-223.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products discussed on this page are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.