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Iodine
Bottom line
In our scoring, Iodine rates mixed evidence: the evidence is mixed for adequate iodine in pregnancy and lactation for fetal neurodevelopment. Our top-scored product is Pure Encapsulations Iodine (Potassium Iodide) 225 mcg (90/100), about $0.16 a day at a clinical dose of RDA is 150 mcg/day for non-pregnant adults. Bottom line: promising but not settled, so manage expectations. This is our opinion, not medical advice; talk to your clinician before starting.
Most supplements punish you mildly for guessing wrong.
- Evidence
- Mixed Evidence
- Category
- Vitamins & Minerals
- Best form
- Potassium iodide (KI) - standard, well-absorbed supplemental form used in clinical trials and prenatal vitamins
- Effective dose
- RDA is 150 mcg/day for non-pregnant adults
- Lab tested
- 5 of 9 products
- Category
- Vitamins & Minerals
- Best form
- Potassium iodide (KI) - standard, well-absorbed supplemental form used in clinical trials and prenatal vitamins
- Effective dose
- RDA is 150 mcg/day for non-pregnant adults
- Lab tested
- 5 of 9 products
Key takeaways
- →If you are pregnant or breastfeeding, take a prenatal with 150 mcg iodine; the ATA recommends it and the evidence on fetal brain development is the strongest part of the iodine case.
- →If you eat iodized salt, dairy, seafood, or seaweed, you probably do not need a separate iodine supplement. US population-level intake is adequate-to-borderline.
- →Megadose iodine (Iodoral 12.5 mg, Lugol's drops, 'thyroid optimization' protocols) is not supported by RCT evidence and can trigger Wolff-Chaikoff hypothyroidism or worsen Hashimoto's in susceptible people.
- →Potassium iodide at 150-225 mcg is the form used in clinical trials and prenatal vitamins; kelp is variable batch-to-batch; molecular I2 (Ghent/Kessler form) is uncommon in retail.
- →Test iodine status (urine iodine) and TSH/thyroid antibodies before exceeding the 1,100 mcg/day tolerable upper limit. Talk to a physician before megadose protocols.
What Is Iodine?
Most supplements punish you mildly for guessing wrong. Iodine is different: take the wrong dose and you can hurt your thyroid more than if you had skipped it entirely. Your body needs iodine to build thyroid hormone (the chemical messenger that sets your metabolism), and a severe shortage causes goiter, an underactive thyroid, and permanent brain damage in a developing baby. The good news is that the US mostly solved this back in the 1920s by adding iodine to table salt. Depending on which survey you read, the average American now sits somewhere between "fine" and "just barely enough." So the reason to supplement here is narrow, and it lives or dies on the dose.
Start with where the evidence is strongest, because that is the part most people came for. First, pregnancy and breastfeeding. The American Thyroid Association (Alexander 2017 guidelines) recommends 150 mcg/day of iodine through a prenatal vitamin, because a growing baby's thyroid runs on the mother's iodine, and even mild shortfall in pregnancy has been linked to lower verbal IQ and reading scores in the child at age 8-9 (Bath 2013, Lancet analysis of 1,040 mother-child pairs). Most US prenatals now include 150-220 mcg for exactly this reason. Second, true deficiency. In parts of Africa, South Asia, and mountainous Europe where the soil is low in iodine, fortification and supplements prevent goiter, severe developmental delay, and the disability that comes with it. That is settled and uncontested. Third, fibrocystic breast pain: Ghent 1993 and Kessler 2004 are small trials using molecular iodine (a specific form called I2, not the potassium iodide in most pills) at 3-6 mg/day that eased breast pain and lumpiness. The signal is real, but the trials are small, the form is uncommon, and most retail "iodine for breasts" products are not the I2 actually tested.
Where it gets contested is "thyroid optimization" with high-dose iodine in people who already get enough. Brownstein-style protocols push 12.5-50 mg/day (that is 50 to 200 times the RDA) of Iodoral or Lugol's, on the theory that everyone is secretly running low and megadoses fix it. The trouble is the evidence behind that theory is case observations, not controlled trials, and the downside is well documented. A big iodine load can flip the thyroid off temporarily (the Wolff-Chaikoff effect, in susceptible people; Markou 2001), tip people with nodular goiter into an overactive thyroid (Jod-Basedow), and trigger or worsen Hashimoto's, the autoimmune attack on the thyroid (Leung 2014, Nature Reviews Endocrinology; Katagiri 2017, PLoS One). One 12.5 mg Iodoral tablet is 83 times the 150 mcg RDA and about 11 times the 1,100 mcg daily ceiling. Taking that every day without first testing your iodine level and thyroid antibodies is a bet against your own endocrine system.
The pattern that matters: with iodine, both too little and too much harm the thyroid, and the safe zone between them is narrower than for almost any other nutrient. More is not better here. If you regularly eat iodized salt, dairy, seafood, or seaweed, you are probably already covered. If you skip iodized salt and eat mostly whole foods or plant-based, a 150 mcg/day potassium iodide tablet is reasonable insurance. Megadosing is not.
Does It Work? The Evidence
How A-F grades workIodine earns a Mixed Evidence rating: the research is suggestive but not settled. Its best-supported uses so far are adequate iodine in pregnancy and lactation for fetal neurodevelopment and prevention of goiter and iodine deficiency disorders in deficient populations (grade A), but the evidence across claims is mixed - each is graded on its own below.
Adequate iodine in pregnancy and lactation for fetal neurodevelopment
Alexander 2017 ATA pregnancy guidelines recommending 150 mcg/day; Bath 2013 Lancet ALSPAC analysis (n=1,040) linking mild maternal deficiency to lower child IQ; Dineva 2020 AJCN systematic review
Prevention of goiter and iodine deficiency disorders in deficient populations
Zimmermann 2008 Lancet review of global iodine deficiency disorders; Zimmermann 2009 Endocrine Reviews; decades of population-scale fortification data
Radiation protection (potassium iodide for thyroid blockade post-exposure)
Established pharmaceutical use (FDA-approved KI tablets for nuclear emergency thyroid blockade); not a daily-use indication for consumer supplements
Hashimoto's thyroiditis (high-dose iodine)
Excess iodine intake is a documented risk factor for triggering and worsening Hashimoto's autoimmune thyroiditis in susceptible individuals (Leung 2014; Markou 2001). Selenium, not iodine, is the trace mineral with positive Hashimoto's trial data
Fibrocystic breast pain (cyclic mastalgia)
Ghent 1993 Can J Surg multi-arm trial of molecular iodine in fibrocystic disease; Kessler 2004 Breast J RCT (n=111) showing 3-6 mg/day molecular I2 reduced breast pain vs. placebo over 5 months
Thyroid hormone production support in iodine-sufficient adults
Mechanistically required as substrate, but RCTs in iodine-replete populations do not show benefit from added iodine; benefit is in correcting deficiency, not exceeding sufficiency
High-dose iodine (12.5-50 mg/day Iodoral/Lugol's) for 'thyroid optimization'
No randomized controlled trials. Clinical observations and uncontrolled case series only. Counterbalanced by Leung 2014 Nat Rev Endocrinol and Katagiri 2017 PLoS One showing excess iodine triggers iodine-induced hypothyroidism and worsens autoimmune thyroid disease
| Grade | Claimed Benefit | Key Studies | Our Verdict |
|---|---|---|---|
| A | Adequate iodine in pregnancy and lactation for fetal neurodevelopment | Alexander 2017 ATA pregnancy guidelines recommending 150 mcg/day; Bath 2013 Lancet ALSPAC analysis (n=1,040) linking mild maternal deficiency to lower child IQ; Dineva 2020 AJCN systematic review | Supported |
| A | Prevention of goiter and iodine deficiency disorders in deficient populations | Zimmermann 2008 Lancet review of global iodine deficiency disorders; Zimmermann 2009 Endocrine Reviews; decades of population-scale fortification data | Supported |
| A | Radiation protection (potassium iodide for thyroid blockade post-exposure) | Established pharmaceutical use (FDA-approved KI tablets for nuclear emergency thyroid blockade); not a daily-use indication for consumer supplements | Supported |
| B | Hashimoto's thyroiditis (high-dose iodine) | Excess iodine intake is a documented risk factor for triggering and worsening Hashimoto's autoimmune thyroiditis in susceptible individuals (Leung 2014; Markou 2001). Selenium, not iodine, is the trace mineral with positive Hashimoto's trial data | Ineffective |
| C | Fibrocystic breast pain (cyclic mastalgia) | Ghent 1993 Can J Surg multi-arm trial of molecular iodine in fibrocystic disease; Kessler 2004 Breast J RCT (n=111) showing 3-6 mg/day molecular I2 reduced breast pain vs. placebo over 5 months | Early Signal |
| C | Thyroid hormone production support in iodine-sufficient adults | Mechanistically required as substrate, but RCTs in iodine-replete populations do not show benefit from added iodine; benefit is in correcting deficiency, not exceeding sufficiency | Not There Yet |
| D | High-dose iodine (12.5-50 mg/day Iodoral/Lugol's) for 'thyroid optimization' | No randomized controlled trials. Clinical observations and uncontrolled case series only. Counterbalanced by Leung 2014 Nat Rev Endocrinol and Katagiri 2017 PLoS One showing excess iodine triggers iodine-induced hypothyroidism and worsens autoimmune thyroid disease | Not There Yet |
How to Choose: Forms, Doses & What Matters
Clinical dose: RDA is 150 mcg/day for non-pregnant adults; 220 mcg/day in pregnancy and 290 mcg/day in lactation. Tolerable upper limit is 1,100 mcg/day from all sources
Best forms: Potassium iodide (KI) - standard, well-absorbed supplemental form used in clinical trials and prenatal vitamins, Kelp / bladderwrack (natural source) - iodine content varies widely batch-to-batch (50-2000 mcg per gram), so doses on the label are estimates, Molecular iodine (I2) - the form used in the Ghent and Kessler fibrocystic breast trials; uncommon in retail supplements, Lugol's solution / Iodoral (5% I2 + 7.5% potassium iodide blend) - megadose protocol form, not appropriate for most users
For everyday coverage, take 150 mcg/day of potassium iodide. That is the RDA, it is the dose in prenatal vitamins, and you can take it any time of day, with food or without. If you are pregnant or breastfeeding, the 150 mcg in your prenatal is usually enough on its own - the goal is 220-290 mcg total per day once you count what you get from food. One thing to check first: if your prenatal already contains iodine, do not pile a separate iodine pill on top of it without reading both labels. Iodine absorbs easily by mouth, so there is no special timing trick to worry about. If you are using a Lugol's or Iodoral product above the 1,100 mcg ceiling, only do that under a doctor's supervision, with iodine and thyroid bloodwork (urinary iodine, TSH, free T4, and TPO antibodies) before and during. One more pairing note: iodine and selenium work together in the thyroid, and for Hashimoto's in particular, selenium has better evidence behind it than adding more iodine.
Who Should Take Iodine?
If you are pregnant or breastfeeding, this is the clearest case: you need 150 mcg/day of supplemental iodine, usually built into your prenatal vitamin, per the American Thyroid Association 2017 guidelines. Beyond that, the people who benefit are the ones not getting iodine from food. That means anyone who skips iodized salt and dairy and does not eat seafood or seaweed - a 150 mcg/day potassium iodide tablet is reasonable insurance. It also means strict plant-based eaters in low-iodine-soil regions (parts of inland Europe, mountainous Asia and Africa), and anyone living in or eating food from a documented iodine-deficient area. If a test shows your urinary iodine is low (under 100 mcg/L in non-pregnant adults, under 150 mcg/L in pregnancy), that is a concrete reason too. For every one of these situations, the right dose is 150 mcg/day, not a megadose protocol.
Who Should Avoid It?
Not for everyone
Side Effects & Safety
Product Scores
9 products scored on dosing accuracy, third-party testing, cost per effective dose, and label transparency.
The Scorecard: 9 Products Compared
Pure Encapsulations Iodine (Potassium Iodide) 225 mcg
Pure Encapsulations$19.50 ÷ 122 days at 225mcg/day (1 serving × 225mcg)
The cleanest formulation in this category. Best pick for people with multiple food sensitivities or anyone who wants dose precision from potassium iodide rather than variable kelp.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
NOW Foods Kelp 150 mcg (200 tablets)
NOW Foods$6.99 ÷ 233 days at ~129mcg/day (0.9 servings × 150mcg)
The default pick for anyone who wants a 150 mcg/day insurance dose without overpaying. Kelp is less precise than potassium iodide but adequate for population-level adequacy.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Thorne Iodine & Tyrosine (225 mcg + 500 mg L-Tyrosine)
Thorne$24.00 ÷ 60 days at 225mcg/day (1 serving × 225mcg)
Reasonable pick if you want Thorne's quality program and the tyrosine addition appeals to you. For pure iodine adequacy, Pure Encapsulations Iodine is the same potassium iodide dose at lower cost.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Solgar North Atlantic Kelp 200 mcg (250 tablets)
Solgar$14.99 ÷ 250 days at 200mcg/day (1 serving × 200mcg)
Solid mid-tier kelp option. For someone who wants a slightly higher dose than the NOW 150 mcg with similar pricing and a recognizable brand.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Life Extension Sea-Iodine 1000 mcg (60 caps)
Life Extension$11.00 ÷ 61 days at 1000mcg/day (1 serving × 1000mcg)
Real but narrow use case. If you have documented deficiency on urinary iodine testing or live in a low-iodine region, this is a reasonable corrective dose under physician guidance. For everyday adequacy, the 150 mcg NOW or 225 mcg Pure Encapsulations options are safer defaults.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Standard Process Prolamine Iodine 600 mcg (90 tablets)
Standard Process
$16.50 ÷ 92 days at 600mcg/day (1 serving × 600mcg)
Practitioner-channel product. The 600 mcg dose is not appropriate for everyday use without a clinical reason. If a practitioner recommends this specifically, follow their guidance; otherwise the 150-225 mcg options are better defaults.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Global Healing Detoxadine Nascent Iodine (1 oz)
Global Healing
$42.95 ÷ 205 days at 1950mcg/day (1 serving × 1950mcg)
If the 'nascent' marketing pulls you in, understand that the chemistry claim does not survive scrutiny - iodine equilibrates in solution regardless of starting form. You are paying a premium for a positioning claim, not a documented bioavailability advantage. Same megadose-iodine cautions apply.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
J.CROW's Lugol's Solution of Iodine 2% (2 oz)
J.CROW's
$19.95 ÷ 998 days at ~3008mcg/day (1.2 servings × 2500mcg)
Traditional Lugol's solution. Useful as a precision dropper format if you and your physician have decided on a megadose protocol with monitoring. Not appropriate for self-directed daily use without testing and oversight.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Optimox Iodoral 12.5 mg (90 tablets)
Optimox
$40.95 ÷ 91 days at 12500mcg/day (1 serving × 12500mcg)
Listed because users will buy it regardless. This is not a general-population supplement. If you are working with a functional medicine practitioner on a megadose iodine protocol, you should also be getting baseline and follow-up urinary iodine, TSH, free T4, and TPO antibody testing. Do not start this on your own.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Pure Encapsulations Iodine (Potassium Iodide) 225 mcg Pure Encapsulations | NOW Foods Kelp 150 mcg (200 tablets) NOW Foods | Thorne Iodine & Tyrosine (225 mcg + 500 mg L-Tyrosine) Thorne | Solgar North Atlantic Kelp 200 mcg (250 tablets) Solgar | Life Extension Sea-Iodine 1000 mcg (60 caps) Life Extension | Standard Process Prolamine Iodine 600 mcg (90 tablets) Standard Process | Global Healing Detoxadine Nascent Iodine (1 oz) Global Healing | J.CROW's Lugol's Solution of Iodine 2% (2 oz) J.CROW's | Optimox Iodoral 12.5 mg (90 tablets) Optimox |
|---|---|---|---|---|---|---|---|---|---|
| Brand Score | 90/100Winner | 86/100 | 84/100 | 82/100 | 78/100 | 72/100 | 65/100 | 62/100 | 60/100 |
| Dosing & Form | 24/25Winner | 23/25 | 21/25 | 22/25 | 18/25 | 18/25 | 16/25 | 14/25 | 12/25 |
| Purity | 23/25 | 20/25 | 24/25Winner | 19/25 | 20/25 | 17/25 | 15/25 | 15/25 | 17/25 |
| Value | 18/25 | 23/25Winner | 17/25 | 22/25 | 20/25 | 18/25 | 16/25 | 18/25 | 15/25 |
| Transparency | 25/25Winner | 20/25 | 22/25 | 19/25 | 20/25 | 19/25 | 18/25 | 15/25 | 16/25 |
| Cost/Day | $0.16 | $0.03 | $0.40 | $0.06 | $0.18 | $0.18 | $0.21 | $0.02Winner | $0.45 |
| Dose/Serving | 225mcg | 150mcg | 225mcg | 200mcg | 1000mcg | 600mcg | 1950mcg | 2500mcg | 12500mcg |
| Form | Potassium iodide (vegetarian capsule) | Organic kelp (Laminaria) tablet | Potassium iodide + L-tyrosine (capsule) | North Atlantic kelp tablet | Kelp + bladderwrack blend (vegetarian capsule) | Prolamine iodine (zein-bound) tablet | Nascent iodine (liquid drops) | Lugol's solution 2% (liquid drops) | Molecular iodine (I2) + potassium iodide tablet |
| Third-Party Tested | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | No | No | No | No |
| Proprietary Blend | No | No | No | No | No | No | No | No | No |
Frequently Asked Questions
Do I need an iodine supplement if I eat iodized salt?
Probably not. A half-teaspoon of US iodized salt provides roughly 150 mcg of iodine - the full adult RDA. Dairy is also a significant US iodine source (residual from livestock feed and equipment sanitizers), as are seafood and bread. Population surveys (NHANES) show median US iodine status is adequate, though some subgroups - pregnant women, people on plant-based diets, people using non-iodized specialty salts - run lower. If you are healthy, eat a varied diet, and use iodized salt, a separate iodine supplement is not needed.
How much iodine do I need in pregnancy?
The American Thyroid Association's 2017 pregnancy guidelines (Alexander et al.) recommend that pregnant and breastfeeding women in North America take 150 mcg of supplemental iodine per day, typically via a prenatal vitamin, on top of dietary intake. The total target is approximately 220 mcg/day in pregnancy and 290 mcg/day in lactation (the RDAs for those states). Most US prenatal vitamins now include 150-220 mcg iodine; check the label, because not all do. Fetal brain development depends on maternal thyroid hormone, which requires iodine - mild maternal deficiency has been linked in the ALSPAC cohort (Bath 2013, Lancet) to lower verbal IQ in the child at age 8-9.
Is Iodoral or Lugol's safe at 12.5 mg/day?
For most people, this dose is not supported by evidence and carries meaningful risk. A 12.5 mg Iodoral tablet is roughly 83 times the 150 mcg adult RDA and over 10 times the 1,100 mcg/day tolerable upper limit set by the Institute of Medicine. The Brownstein protocol's rationale is that population iodine intake has fallen and megadoses correct a hidden epidemic; the evidence base for this is clinical observation, not randomized trials. The downside is documented: large iodine loads can trigger transient or persistent hypothyroidism (Wolff-Chaikoff effect, Markou 2001), precipitate hyperthyroidism in people with nodular goiter (Jod-Basedow), and worsen or unmask Hashimoto's autoimmune thyroiditis (Leung 2014, Nature Reviews Endocrinology). If you want to try megadose iodine, do it only under physician supervision with baseline and follow-up urinary iodine, TSH, free T4, and TPO antibody testing. Most people should stop at 150-300 mcg/day.
Will iodine help my Hashimoto's?
Probably not, and it may make it worse. Iodine is a substrate for thyroid hormone, but in Hashimoto's, the problem is autoimmune attack on the thyroid gland, not iodine substrate scarcity. Excess iodine is a documented environmental trigger for Hashimoto's onset and progression in susceptible individuals (Leung 2014; Katagiri 2017). The trace mineral with positive Hashimoto's trial data is selenium - 200 mcg/day of selenomethionine reduces TPO antibodies in multiple RCTs. Stay at the 150 mcg iodine RDA from diet and any prenatal-style supplement, and discuss anything above that with your endocrinologist.
Is kelp a reliable iodine source?
Less reliable than potassium iodide. Kelp iodine content varies enormously batch-to-batch and species-to-species - the literature reports anywhere from 50 mcg to over 2,000 mcg per gram of dried kelp. A label claim of '150 mcg from kelp' is an estimate based on assayed lots, not a guarantee. For supplemental iodine where dose precision matters (pregnancy, documented deficiency, anyone counting micrograms), potassium iodide is the better choice. Kelp is fine as a generic insurance dose for someone who otherwise gets little iodine, but do not stack multiple kelp products or assume label dose is exact.
What is nascent iodine and is it better?
Nascent iodine is a marketing term for iodine solutions made by electrically dissociating I2 molecules into a 'monatomic' or 'pre-atomic' state, supposedly making it more bioavailable. The chemistry claim does not survive contact with how iodine actually behaves in solution and in the gut - dissolved iodine equilibrates rapidly regardless of starting form. There is no peer-reviewed trial showing nascent iodine outperforms potassium iodide on any thyroid endpoint. It is not inherently bad as an iodine source, but the premium price and the bioavailability claim are not supported by evidence. Potassium iodide costs less and has the trial record.
How do I know if I am iodine-deficient?
Spot urinary iodine concentration is the standard population-level marker; for an individual, a 24-hour urine iodine collection is more accurate. WHO criteria classify adequate non-pregnant adult iodine status as urinary iodine 100-299 mcg/L; below 100 mcg/L is mild-to-moderate deficiency. In pregnancy the adequate range is 150-249 mcg/L. Symptoms of overt deficiency - goiter, fatigue, cold intolerance, weight gain, dry skin, brain fog - overlap entirely with hypothyroidism from any cause, so symptoms alone are not diagnostic. If you are concerned, urinary iodine testing and a TSH check via your physician are the right starting point, not empirical megadose iodine.
Can iodine and selenium be taken together?
Yes, and they work together physiologically. Iodine is the substrate for thyroid hormone synthesis; selenium-dependent deiodinase enzymes convert T4 to active T3, and selenium-dependent glutathione peroxidase protects the thyroid gland from the oxidative stress of hormone production. In iodine deficiency combined with selenium deficiency, thyroid damage is worse than with either deficiency alone. For practical supplementation: 150 mcg iodine and 100-200 mcg selenomethionine is a reasonable pairing for someone with documented or suspected dual insufficiency. Do not stack high-dose iodine and high-dose selenium - both have U-shaped dose-response curves and the toxic ceiling is closer than the deficient floor.
Related Reading
Sources
- Alexander EK, Pearce EN, Brent GA, et al. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid. 2017;27(3):315-389.
- Zimmermann MB, Jooste PL, Pandav CS. Iodine-deficiency disorders. Lancet. 2008;372(9645):1251-1262.
- Zimmermann MB. Iodine deficiency. Endocr Rev. 2009;30(4):376-408.
- Bath SC, Steer CD, Golding J, Emmett P, Rayman MP. Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC). Lancet. 2013;382(9889):331-337.
- Dineva M, Fishpool H, Rayman MP, Mendis J, Bath SC. Systematic review and meta-analysis of the effects of iodine supplementation on thyroid function and child neurodevelopment in mildly-to-moderately iodine-deficient pregnant women. Am J Clin Nutr. 2020;112(2):389-412.
- Ghent WR, Eskin BA, Low DA, Hill LP. Iodine replacement in fibrocystic disease of the breast. Can J Surg. 1993;36(5):453-460.
- Kessler JH. The effect of supraphysiologic levels of iodine on patients with cyclic mastalgia. Breast J. 2004;10(4):328-336.
- Markou K, Georgopoulos N, Kyriazopoulou V, Vagenakis AG. Iodine-induced hypothyroidism. Thyroid. 2001;11(5):501-510.
- Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2014;10(3):136-142.
- Leung AM, Braverman LE. Iodine-induced thyroid dysfunction. Curr Opin Endocrinol Diabetes Obes. 2012;19(5):414-419.
- Katagiri R, Yuan X, Kobayashi S, Sasaki S. Effect of excess iodine intake on thyroid diseases in different populations: A systematic review and meta-analyses including observational studies. PLoS One. 2017;12(3):e0173722.
- NIH Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. Updated 2024.
Scores and tiers are our independent opinion, formed by applying a published rubric to label data, third-party certifications, and the research record. They are not statements of objective fact about a product and not a lab test. Where we report a brand-specific fact, it comes from a cited source or a public certification; where verification is missing, we say so rather than assume a result.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.