Iodine (I)
Iodine is a nutrient your body needs to make thyroid hormones — the hormones that set your metabolic rate, support growth, and are critical for a developing baby's brain. The UK Reference Nutrient Intake (RNI) is 140 µg/day for adults, rising to 200 µg/day in pregnancy and breastfeeding. In the UK most people get their iodine from cow's milk and dairy products, white fish (cod, haddock), and eggs — unlike the US and most of Europe, the UK does NOT add iodine to table salt at the population level. The UK has a quiet public-health problem here. The Vanderpump 2011 Lancet survey of UK schoolgirls (PMID 21640375) found that 51% had mild iodine deficiency by WHO criteria and 16% had moderate deficiency — and subsequent National Diet and Nutrition Survey data have shown the same pattern in pregnant women, women planning pregnancy, vegans, and people who avoid dairy. Bath 2013 Lancet (PMID 23706508) analysed the UK ALSPAC birth cohort and found children born to mothers with low first-trimester iodine had lower verbal IQ and reading scores at age 8 — even though the UK is "only mildly" deficient. Talk to your midwife if you are pregnant or trying to conceive, particularly if you don't eat dairy or fish. The standard UK pregnancy supplement bundle is folic acid + vitamin D, with iodine increasingly added (150 µg/day potassium iodide) for women whose dietary intake is low. Two safety points: both too little AND too much iodine can disrupt thyroid function, so do NOT mega-dose; and AVOID kelp / seaweed-based iodine supplements unless the iodine content per serving is declared and batch-tested — kelp can deliver anywhere from 100 µg to 8,000 µg iodine per gram, which is genuinely unsafe at the upper end. Potassium iodide at 100-150 µg/day is the controlled supplement form.
Camden Medicals editorial · Last reviewed 12 June 2026 · Next review December 2026
- Cross-checked against
- NHS
- NICE
- BNF
- EFSA
- FSA
Camden's editorial team independently graded each health claim below on the strength of the published evidence — see the grade beside every condition.
- Class
- Mineral
- Typical daily dose
- Standard UK supplement dose is 100-150 µg/day potassium iodide for general supplementation, or 150 µg/day for pregnancy. NHS pathways for iodine deficiency in adults manage at the 150-200 µg/day range. High-dose clinical iodine preparations (Lugol's, KI tablets in nuclear emergency) are prescriber-supervised and not part of food-supplement context.
- Top use evidence
- Strong
On this page
What it is
Iodine is a chemical element your body needs in tiny amounts to make thyroid hormones — the hormones that regulate how fast you burn energy, how warm you stay, and (crucially in pregnancy) how a developing baby's brain forms. Your thyroid gland sits in the front of your neck and acts as a storage and assembly site for iodine: it concentrates iodine from your bloodstream and uses it to build thyroxine (T4) and triiodothyronine (T3), the two hormones that carry iodine's signal around the body.
Total body iodine in an adult is typically 15-20 mg, with roughly 70-80% concentrated in the thyroid gland — by far the greatest organ-specific concentration of any trace element in the body. Iodine is the halogen element with atomic number 53; in biological systems it exists predominantly as the iodide anion (I⁻).
Dietary iodine sources in the UK have historically been (in descending order of contribution to mean adult intake): cow's milk and dairy products (the dominant source — approximately 50% of UK iodine intake comes from dairy because of iodine-rich livestock feed and iodine teat-dip used in mastitis prevention); white fish (haddock, cod, plaice — typical content 100-300 µg per 100 g); eggs (~25 µg per egg); sea fish more broadly; iodised salt (used by some UK consumers but the UK does NOT iodise salt at population level — a public-health policy gap compared to most developed countries).
Iodine in supplements is most commonly delivered as potassium iodide (KI) or potassium iodate (KIO3) — both well-absorbed forms with predictable, consistent µg-per-serving doses. Kelp-derived iodine products are also marketed but with substantial variability — kelp species have natural iodine concentrations spanning 100 µg to 8000 µg per gram of dried herb depending on species (Laminaria, Saccharina, Ascophyllum, Fucus) and harvest conditions, and undeclared / unbatched kelp supplements regularly deliver high-dose iodine or wildly variable doses. Camden's kelp entry addresses this as the load-bearing safety issue.
Vanderpump et al. 2011 (Lancet) sampled iodine status across UK schoolgirls and reported mild iodine insufficiency by WHO criteria — median urinary iodine concentration 80 µg/L (WHO sufficiency threshold 100 µg/L). Subsequent National Diet and Nutrition Survey rolling programme has consistently shown UK pregnant women, women of childbearing age, vegans, dairy-avoiders, and those on plant-based diets without iodine-fortified plant drinks to have median intakes below the UK RNI. The British Dietetic Association iodine position paper (2018, updated 2021) and the British Thyroid Foundation pregnancy guidance both flag the gap.
At a glance
- UK RNI: 140 µg/day adults; 200 µg/day in pregnancy and breastfeeding. UK NRV (label %): 150 µg/day; EFSA tolerable upper intake 600 µg/day for adults. The UK is NOT a salt-iodisation country — most iodine comes from cow's milk and dairy (30-50 µg per glass), white fish, and eggs.
- Pregnancy is the highest-stakes life stage. The Vanderpump 2011 Lancet schoolgirl survey (PMID 21640375) and Bath 2013 Lancet ALSPAC analysis (PMID 23706508, n=1,040 UK pregnant women) found UK mild deficiency and higher odds of lowest-quartile verbal IQ + reading at age 8 where first-trimester maternal iodine was low. Talk to your midwife about adding 150 µg potassium iodide if your dietary intake is low.
- Both deficiency AND excess cause thyroid dysfunction. If you have autoimmune thyroid disease (Hashimoto, Graves), thyroid nodules, or pre-existing hyper/hypothyroidism, do NOT routinely supplement iodine — talk to your endocrinology team. AVOID kelp / seaweed iodine supplements without declared content — variability is 100-fold between batches; the controlled form is potassium iodide at 100-150 µg/day.
- Six UK Article 13.1 authorised claims (thyroid hormones, thyroid function, cognitive function, energy-yielding metabolism, nervous system, skin maintenance) plus a separate normal-growth-of-children claim — the broadest claim profile of any UK mineral.
What people use it for
UK pregnant women and women planning pregnancy
150 µg/day iodine (typically as potassium iodide) alongside 400 µg folate, 10 µg vitamin D, and any indicated iron is the supplement profile increasingly recommended by UK pregnancy guidance for women whose dietary intake of dairy and white fish is below the level required for the higher pregnancy RNI of 200 µg/day. The British Thyroid Foundation pregnancy iodine guidance and RCOG Green-top 23 supplement-in-pregnancy framework both flag iodine for women on dairy-avoidant or vegan diets. Talk to your midwife. Avoid kelp-based supplements in pregnancy because of iodine-content variability. [3,2]
Some evidenceStrongUK adults on vegan / plant-based diets without iodine-fortified plant drinks
Plant-based diets without iodised salt and without iodine-fortified plant drinks are at substantial risk of iodine insufficiency. Soya, oat, and almond drinks vary in iodine fortification — some UK organic-certified plant drinks contain very little iodine because organic livestock-feed iodine practices and organic plant-drink fortification both differ. Read the back-of-pack nutrition panel; if iodine is not listed, the product is unfortified. Either choose an iodine-fortified plant drink or supplement at 100-150 µg/day potassium iodide. [1]
Some evidenceModerateUK adults whose dietary iodine intake is adequate (regular dairy, white fish, or eggs)
Most UK adults consuming a typical mixed diet meet iodine RNI from food without supplementation. Routine iodine supplementation is not necessary. Add iodine if dietary intake is insufficient (vegan, dairy-avoidant, low-fish) or if a clinical context requires it. [1]
Some evidenceStrongAdults with diagnosed autoimmune thyroid disease (Hashimoto, Graves)
Do NOT routinely add iodine without endocrinology input. In Hashimoto thyroiditis, iodine supplementation can accelerate autoimmune thyroid destruction and worsen hypothyroidism. In Graves disease, iodine load can trigger iodine-induced hyperthyroidism (Jod-Basedow). Seaweed and kelp products are particularly hazardous because of iodine-content variability. Talk to the endocrinology team managing your thyroid condition. [4,3]
Some evidenceStrongAdults considering iodine for "breast health" or "fibrocystic breast disease"
Marketing of iodine for breast tissue is over-stated in alternative-medicine literature. UK NHS / NICE pathways for fibrocystic breast disease do not list iodine supplementation. Talk to your GP about any breast-tissue concern. [11]
Popular, not provenInsufficient
How it works
Thyroid hormone synthesis. Iodide is actively concentrated in thyroid follicular cells via the sodium-iodide symporter (NIS). Inside the follicle, iodide is oxidised by thyroid peroxidase (TPO) and incorporated into tyrosine residues on thyroglobulin, forming mono-iodotyrosine and di-iodotyrosine. Coupling reactions then generate thyroxine (T4 — four iodine atoms per molecule) and triiodothyronine (T3 — three iodine atoms). Roughly 90% of secreted thyroid hormone is T4; T3 is the more biologically active form, and most circulating T3 is generated in peripheral tissues by deiodinase enzymes that remove an iodine atom from T4. The deiodinase enzymes are SELENIUM-dependent — selenium status modulates the conversion of T4 to T3, the basis for the iodine-selenium pairing.
Thyroid hormone action. Thyroid hormones bind nuclear thyroid hormone receptors and transcriptionally regulate metabolic rate (basal energy expenditure, thermogenesis), cardiovascular function (heart rate, contractility), bone turnover, and — critically in foetal and neonatal life — neurological development. Maternal thyroid hormone crosses the placenta in early pregnancy before the foetal thyroid is functional; maternal iodine status in the first trimester therefore directly influences foetal brain development. Bath 2013 (Lancet) analysed the ALSPAC UK birth cohort and reported lower verbal IQ at age 8 in children born to mothers with first-trimester urinary iodine concentration <150 µg/g creatinine.
Iodine excess — Wolff-Chaikoff and Jod-Basedow. At very high iodine intakes, thyroid hormone synthesis is paradoxically reduced (Wolff-Chaikoff effect) — a transient protective mechanism that normally adapts within 48 hours. In some individuals (autoimmune thyroiditis, fetal / neonatal exposure, post-hyperthyroidism) the escape from Wolff-Chaikoff fails and iodine-induced hypothyroidism results. Conversely, in individuals with autonomous thyroid nodules or undiagnosed Graves' disease, sudden iodine load can trigger iodine-induced hyperthyroidism (Jod-Basedow phenomenon). The clinical implication is that "more iodine is better" is wrong — both deficiency and excess cause thyroid dysfunction, and the dose range delivering sufficiency without harm is narrower than for most other minerals.
Extra-thyroidal iodine. Iodine is also present in mammary tissue (where it is concentrated in breast milk during lactation), salivary glands, gastric mucosa, and the choroid plexus. Extra-thyroidal roles are less well-characterised but include antioxidant signalling and possible mammary-tissue physiology — though the latter has been over-claimed in alternative-medicine literature ("iodine for breast health") without trial evidence.
Common myths
Myth""More iodine is always better — it boosts the thyroid.""
RealityBoth deficiency and excess produce thyroid dysfunction. Above the EFSA tolerable upper intake (600 µg/day adults, 200 µg/day children 1-3, 250 µg/day children 4-6, 300 µg/day children 7-10) the risks of iodine-induced hyperthyroidism, iodine-induced hypothyroidism, and (in autoimmune-prone individuals) thyroiditis flare rise. The dose range delivering sufficiency without harm is narrower than for most minerals — "more is better" is wrong.
Myth""You can get all your iodine from sea salt or pink Himalayan salt.""
RealityUntrue. Standard sea salt and pink Himalayan salt are NOT iodised — their iodine content is negligible (typically 1-2 µg per 5 g salt). Only specifically labelled "iodised salt" provides meaningful iodine, and even that is not used at UK population level. Iodised salt typically delivers roughly 20–40 µg iodine per gram salt — making meaningful intake possible only at salt intakes above current UK public-health recommendations. [1]
Myth""Kelp / seaweed is a natural iodine source.""
RealityNatural yes, controlled no. Kelp species (Laminaria, Saccharina, Ascophyllum, Fucus) have natural iodine content spanning roughly 100 µg to 8000 µg per gram of dried herb depending on species, location of harvest, and processing. Undeclared / unbatched kelp supplements regularly deliver supratherapeutic iodine doses or wildly variable doses between bottles. Multiple case reports document iodine-induced thyroid dysfunction from kelp supplements. Camden''s kelp entry addresses this as the load-bearing safety issue. For controlled iodine supplementation, potassium iodide is the standard form.
Myth""Iodine deficiency only happens in developing countries.""
RealityUntrue for the UK. Vanderpump 2011 Lancet schoolgirl survey and subsequent NDNS rolling-programme data show mild iodine insufficiency by WHO criteria in significant fractions of UK adolescent girls, women of childbearing age, pregnant women, vegans, dairy-avoiders. UK is also NOT a salt-iodisation country at population level — a public-health policy gap. The UK iodine status is not equivalent to severe-deficiency settings but is also not "fully sufficient like the US". [1]
Myth""High-dose iodine treats thyroid disease.""
RealityHigh-dose iodine is a clinical preparation used in defined circumstances (Lugol''s solution pre-thyroidectomy, radioactive iodine in Graves'' or thyroid cancer, potassium iodide in nuclear emergency exposure). These are prescriber-supervised clinical contexts — not food-supplement contexts. Self-supplementation of iodine for diagnosed thyroid disease is not a UK-recognised pathway; talk to the endocrinology team managing your thyroid. [4,3]
What people say online
Iodine discourse on TikTok and Reddit splits across four narratives: pregnancy iodine ("the gap in the NHS bundle" — generally accurate, sometimes overstated); kelp / seaweed as a "natural iodine source" (safety-problematic given the 100-fold variability); "iodine for breast health" (legacy alternative-medicine framing with no UK clinical evidence); and high-dose iodine for "thyroid healing" (often associated with autoimmune thyroid worsening). This section surfaces the discourse without naming individuals.
Trending claims
- TikTok #pregnancysupplements + Reddit r/ScienceBasedParentinghigh visibility
Claim: The NHS pregnancy bundle is missing iodine — buy a US pregnancy vitamin
Reality check: The underlying signal is real — UK iodine status sits in the mild-deficiency band per Vanderpump 2011 (PMID 21640375) and Bath 2013 ALSPAC (PMID 23706508) data, and the NHS pregnancy supplement bundle (folic acid + vitamin D) does not formally include iodine. But "buy a US pregnancy vitamin" is the wrong solution — most modern UK pregnancy multivitamins now include 150 µg/day potassium iodide. Talk to your midwife about adding a UK pregnancy multi with iodine if your dietary intake is low. [8,9]
- TikTok #natural #wellness + alternative-health Reddithigh visibility
Claim: Kelp / seaweed is the natural way to get iodine
Reality check: Unsafe without batch-tested content. Kelp species (Laminaria, Saccharina, Ascophyllum, Fucus) deliver anywhere from 100 to 8,000 µg iodine per gram of dried herb — a 100-fold range. Undeclared / unbatched kelp supplements have caused iodine-induced thyroid dysfunction in case-report and surveillance literature. Controlled iodine supplementation is potassium iodide at 100-150 µg/day — predictable dose, no batch variability. Camden's kelp entry is the load-bearing safety reference.
- TikTok #thyroidhealing + alternative-medicine Redditmedium visibility
Claim: High-dose iodine heals autoimmune thyroid / Hashimoto
Reality check: Unsafe in autoimmune thyroid disease. High-dose iodine can accelerate autoimmune thyroid destruction in Hashimoto thyroiditis and trigger iodine-induced hyperthyroidism (Jod-Basedow) in autonomous nodules or undiagnosed Graves. UK NICE pathway for diagnosed autoimmune thyroid disease is levothyroxine replacement (Hashimoto) or antithyroid medication / radioactive iodine / surgery (Graves). Self-supplementing iodine in this context is contraindicated without endocrinology input.
- TikTok + women's-health Reddit (older content)low visibility
Claim: Iodine helps fibrocystic breast disease / breast pain
Reality check: This is a legacy alternative-medicine framing derived from small uncontrolled US studies in the 1990s (Ghent 1993). UK NHS / NICE pathways for fibrocystic breast disease, cyclical mastalgia, and breast pain do NOT include iodine supplementation. Standard NHS pathway is GP review, exclusion of breast cancer, and symptomatic management with simple analgesia + supportive bra.
Where the conversation lives
- TikTok hashtags: #pregnancysupplements, #pregnancyiodine, #iodine, #thyroidhealing, #hashimotos, #kelp, #seamoss
- Reddit subs: r/ScienceBasedParenting, r/Mothers, r/Hashimotos, r/thyroid, r/Supplements, r/Nutrition
- Forums: British Thyroid Foundation, Thyroid UK charity, Verity-PCOS UK (preconception iodine context)
Questions people are searching
- I'm pregnant — should I take an iodine supplement?
- I've cut out dairy — am I getting enough iodine?
- I have Hashimoto's — should I take iodine?
- How much iodine is in my multivitamin?
- Is iodised salt available in UK shops?
- Is kelp / sea moss safe as an iodine source?
Who drives the discourse: The discourse is driven by four creator classes: pregnancy / midwife / nutritionist creators (most NHS-aligned; surfacing the iodine gap in the UK NHS bundle); thyroid- condition creators (Hashimoto and Graves, often pushing against high-dose iodine for autoimmune flare reasons — mostly accurate); alternative-medicine / wellness creators (kelp / seaweed / sea moss as natural iodine — frequently unsafe framing); and breast-health creators (a smaller legacy cluster around "iodine for fibrocystic disease"). Verifera editorial does not name individuals.
Social-media trends change quickly. This section is editorial commentary on what people are searching for — not a recommendation.
Common online questions
Synthesised from the questions UK shoppers most often ask online about Iodine (I). Each answer is editorial and links to its evidence in the Sources list below.
I'm pregnant — should I take an iodine supplement?
UK pregnancy iodine guidance increasingly recommends 150 µg/day iodine alongside the standard 400 µg folate and 10 µg vitamin D for women whose dietary dairy and white-fish intake is low. If you are vegan, dairy-avoidant, or rarely eat fish, talk to your midwife about adding an iodine-containing pregnancy multivitamin (most UK pregnancy multis include 150 µg potassium iodide). Avoid kelp / seaweed-based iodine supplements in pregnancy because of variable iodine content. [2]
I've cut out dairy — am I getting enough iodine?
Possibly not. Dairy provides roughly 50% of UK adult iodine intake. Cutting it out without compensating from other sources (white fish, eggs, iodised salt, iodine-fortified plant drinks, or a 100-150 µg/day potassium iodide supplement) can produce mild iodine insufficiency. Read the back-of-pack nutrition panel of your plant drink — if iodine is not listed, the product is not fortified. [1]
I have Hashimoto's — should I take iodine?
Not without endocrinology input. Iodine supplementation can accelerate autoimmune thyroid destruction in Hashimoto and worsen hypothyroidism. Levothyroxine replacement therapy is the standard NHS treatment; adding iodine without endocrinology review is not advised. [3]
How much iodine is in my multivitamin?
Read the per-serving panel — UK NRV 150 µg, expressed as %. A typical UK adult multivitamin delivers 100-150% NRV (150-225 µg). UK pregnancy multivitamins typically deliver 100% pregnancy RNI (150 µg) — close to but not at the 200 µg pregnancy RNI; dietary iodine from dairy, fish, or fortified plant drinks would top up the rest.
Is iodised salt available in UK shops?
Yes — major supermarkets stock iodised table salt as a specialty SKU (typically Saxa or own-brand iodised). It is not the default UK table salt because UK has not adopted population-level salt iodisation. Iodised salt typically delivers roughly 20–40 µg iodine per gram — useful in cooking but substituting heavy-iodised-salt use to meet RNI goes against UK public-health salt-reduction guidance (≤6 g/day total salt for adults). Better routes: dairy, white fish, eggs, fortified plant drinks, or a controlled potassium iodide supplement. [1]
⚖️ The official position
What may lawfully be claimed about Iodine (I) in Great Britain. This is a regulatory position, not an evidence grade.
A health claim is authorised in Great Britain.
“Iodine contributes to normal cognitive function”
“Iodine contributes to normal energy-yielding metabolism”
“Iodine contributes to the normal functioning of the nervous system”
“Iodine contributes to the maintenance of normal skin”
“Iodine contributes to the normal production of thyroid hormones and to normal thyroid function”
“Iodine contributes to normal growth of children”
This claim is authorised for use in Great Britain under the GB Nutrition and Health Claims regulation. A product may carry it when it provides at least 15% of the UK NRV per recommended daily portion.
Authorised UK health claims
Verbatim from the GB Nutrition and Health Claims Register (Reg 432/2012 as assimilated in GB). A product can carry these claims when it provides at least 15% of the UK NRV per recommended daily portion.
6 authorised claims — show / hide
- "Iodine contributes to normal cognitive function"
- "Iodine contributes to normal energy-yielding metabolism"
- "Iodine contributes to the normal functioning of the nervous system"
- "Iodine contributes to the maintenance of normal skin"
- "Iodine contributes to the normal production of thyroid hormones and to normal thyroid function"
- "Iodine contributes to normal growth of children"
UK regulatory landscape
UK regulatory tier: Food supplement
Iodine supplements sit under the UK Food Supplements (England) Regulations 2003 (and devolved equivalents) plus the retained-EU Nutrition and Health Claims Regulation. Six Article 13.1 authorised function claims apply (thyroid hormone synthesis, thyroid function, cognitive function, energy-yielding metabolism, nervous system function, skin maintenance) plus a separate growth-of-children claim — the broadest authorised-claim profile of any UK mineral. Iodine is NOT a novel food under the retained Novel Foods Regulation. EFSA tolerable upper intake for adults is 600 µg/day from diet plus supplements.
What crosses the tier
| Condition | Crosses to |
|---|---|
| Marketing for diagnosed hyper- or hypothyroidism, Hashimoto thyroiditis, Graves disease, or thyroid nodules | |
| Marketing iodine for fibrocystic breast disease, breast pain, or "breast health" | |
| Marketing high-dose iodine (≥1 mg/day = 1000 µg/day) for general adult use | |
| Kelp / seaweed iodine supplements without batch-tested iodine content per serving | |
| Marketing iodine alongside anti-thyroid medication, amiodarone, or lithium without prescriber-input warning |
Permitted claims
Six UK Article 13.1 authorised function claims (descriptive summary; the verbatim register text is captured in the GB NHC register snapshot and reproduced word-for-word in the authorised health claims block above): (1) "Iodine contributes to normal cognitive function"; (2) "Iodine contributes to normal energy-yielding metabolism"; (3) "Iodine contributes to the normal functioning of the nervous system"; (4) "Iodine contributes to the maintenance of normal skin"; (5) "Iodine contributes to the normal production of thyroid hormones and normal thyroid function"; (6) "Iodine contributes to normal growth of children" (the child- specific claim). Claims may be used where the food contains a significant amount of iodine per the Annex of the NHCR (≥15% of the 150 µg/day NRV per 100 g / 100 ml or per portion as applicable).
Cross-jurisdiction note
The US, Switzerland, most of Europe, Canada, Australia, and New Zealand have population-level salt iodisation programmes. The UK does NOT — iodine intake in the UK is reliant on dairy, fish, and (recently) iodine-fortified plant drinks. The UK iodine status (Vanderpump 2011 PMID 21640375 — UK schoolgirls 51% mild-deficient; Bath 2013 PMID 23706508 — ALSPAC pregnant women mild-deficient) is directly attributable to this policy gap. UK debate on salt iodisation is open but no policy has been adopted.
UK regulatory rules evolve. This summary is editorial — businesses should consult regulatory counsel; consumers should consult their pharmacist or GP.
🔬 Camden’s evidence review
The research Camden reviewed, graded on its strength. This is our own appraisal — it sits beneath the official guidance above, never above it.
Iodine sufficiency and thyroid function in adults
StrongEvidencestrongAdequate iodine intake (≥140 µg/day adults, ≥200 µg/day in pregnancy/lactation) is required for thyroid hormone synthesis; deficiency produces goitre, hypothyroidism, and (in pregnancy) impaired foetal neurological development. UK NDNS rolling programme and Vanderpump 2011 Lancet data show mild iodine insufficiency in significant fractions of UK pregnant women, adolescent girls, and those on dairy-avoidant diets. [1,12]
Maternal iodine status and child neurological development
StrongEvidencestrongSevere iodine deficiency in pregnancy is the leading preventable cause of intellectual disability worldwide. Mild-to-moderate deficiency in the UK ALSPAC cohort (Bath 2013 Lancet) was associated with lower verbal IQ at age 8 in children whose mothers had first-trimester urinary iodine <150 µg/g creatinine. WHO and UK pregnancy guidance recommend ≥200 µg/day total iodine intake in pregnancy and lactation. [3,13,14,15]
Iodine supplementation in iodine-replete population
InsufficientEvidenceinsufficientIn iodine-replete individuals (UK adults consuming regular dairy and white fish), routine iodine supplementation does not produce measurable benefit and can produce harm in those with autonomous nodules or autoimmune thyroid disease. Marketing of high-dose iodine to iodine-replete adults is not a UK-recognised pathway. [3]
Iodine for fibrocystic breast disease, "breast health", or cyclical mastalgia
InsufficientEvidenceinsufficientUK NHS / NICE pathways for fibrocystic breast disease and cyclical mastalgia do not include iodine supplementation. Small uncontrolled US studies (Ghent 1993) reported symptom changes with molecular iodine in mastalgia but the trial evidence is not sufficient for UK clinical recommendation; standard UK pathway is GP review and symptomatic management with simple analgesia. [11]
Effect matrix — per-condition evidence
Per-outcome summary of the published trial corpus: dose ranges studied, duration, evidence grade, and direction of effect. Each row is a citable claim.
| Outcome | Population | Dose | Duration | Evidence | Direction | Sources |
|---|---|---|---|---|---|---|
| Severe iodine deficiency and intellectual disability (cretinism) | pregnancy | 150–250 mcg | 12–40 wk | StrongEvidencestrong | improvement | PMID 15734706 |
| Decades of observational + ecological evidence in severely iodine-deficient populations (e.g. salt-iodisation programmes). HIGH certainty per body-text evidence_quality summary. STRONG grade. Citations empty because the foundation is public-health / ecological, not single-trial PMIDs in body-text. UK is mild-deficient, not severe; this row exists for global context. | ||||||
| Mild maternal iodine deficiency and offspring verbal IQ / reading | pregnancy | — | 12–40 wk | ModerateEvidencemoderate | improvement | PMID 23706508 PMID 30920622 |
| Bath 2013 PMID 23706508 — UK ALSPAC cohort n=1,040 first-trimester urinary iodine and child IQ at age 8. Children of women with iodine-to-creatinine ratio <150 µg/g had OR 1.58 (95% CI 1.09-2.30) of lowest-quartile verbal IQ and lower reading after adjustment for 21 confounders. Strongest UK- context evidence for cognitive stake. UK NHS pregnancy guidance: 150 µg/day. | ||||||
| Pregnancy iodine supplementation (intervention) effect on offspring cognition | pregnancy | 150–300 mcg | 12–40 wk | LimitedEvidencelimited | mixed | PMID 34191411 |
| Machamba 2021 systematic review — 4 RCTs + 4 cohorts in mild-to-moderate iodine-deficiency areas. No significant improvement in children's mental development index or behavioural development index in supplemented groups. Psychomotor development index showed modest signal for poorer gross motor skills. The intervention literature is weaker than the observational cognitive-stake signal — known gap between association and intervention. | ||||||
| UK population mild iodine deficiency (public-health baseline) | adults | — | — | StrongEvidencestrong | not assessed | PMID 21640375 PMID 25274294 |
| Vanderpump 2011 Lancet n=810 — UK schoolgirls median urinary iodine 80.1 µg/L (below WHO 100 µg/L threshold); 51% mild deficient, 16% moderate. Anchors the UK public-health iodine baseline. STRONG grade reflects confidence in the deficiency measurement, not in any supplementation outcome — hence magnitude=not_assessed. | ||||||
Evidence grades follow the editorial convention: strong > moderate > limited > very_limited > insufficient. Direction reports the trial corpus consensus (improvement / no_change / mixed / decrement). Schema cross-emitted at MedicalSubstance.relevantClinicalCondition[].
Clinical literature review
UK guidance leads (see the guidance block — NHS, NICE NG145, EFSA, GB-NHC register, British Dietetic Association, British Thyroid Foundation). Beneath that, the research Camden reviewed: the UK iodine literature splits into three threads — the public-health-deficiency baseline (Vanderpump 2011 Lancet schoolgirl survey PMID 21640375 — UK mild-deficient by WHO criteria); the pregnancy-cognitive stake (Bath 2013 Lancet ALSPAC analysis PMID 23706508 — low first-trimester maternal iodine associated with lower offspring verbal IQ and reading at age 8); and the supplementation-effectiveness question (Machamba 2021 PMID 34191411 systematic review — modest psychomotor signal). UK NICE CKS Hypothyroidism + Hyperthyroidism do not include routine iodine supplementation for thyroid conditions; iodine prescribing in the UK is limited to specialist clinical contexts (Lugol's pre-thyroidectomy, radioactive iodine for Graves / thyroid cancer, KI tablets in nuclear emergency).
Key trials
Vanderpump MPJ, Lazarus JH, Smyth PP et al. · 2011 · Lancet · PMID 21640375
Finding: Cross-sectional survey of UK schoolgirls aged 14-15 across nine UK centres. Median urinary iodine excretion 80.1 µg/L — below the WHO sufficiency threshold of 100 µg/L for adults. 51% of participants had mild iodine deficiency, 16% moderate, 1% severe. Prevalence highest in Belfast (85%). Low milk intake and high egg intake were independent associations.
Relevance: The foundational UK iodine-deficiency public-health paper. Established that the UK — long considered iodine-replete — is in fact mildly iodine-deficient by WHO criteria, with implications for pregnancy and foetal neurodevelopment. Has driven subsequent UK policy debate on salt iodisation.
Bath SC, Steer CD, Golding J, Emmett P, Rayman MP · 2013 · Lancet · PMID 23706508
Finding: Analysis of UK Avon Longitudinal Study of Parents and Children (ALSPAC) cohort, n=1,040 first-trimester pregnant women with urinary iodine and child IQ at age 8. Median urinary iodine 91.1 µg/L (mild-deficient by WHO). After adjustment for 21 confounders, children of women with iodine-to-creatinine ratio <150 µg/g had higher odds of lowest-quartile verbal IQ (OR 1.58, 95% CI 1.09-2.30), reading accuracy (OR 1.69, 1.15-2.49), and reading comprehension (OR 1.54, 1.06-2.23) at age 8. Effect worsened with progressively lower iodine status.
Relevance: The strongest UK-context evidence that mild maternal iodine deficiency has measurable impact on offspring cognitive outcomes. Anchors the UK pregnancy-iodine public-health argument and the British Thyroid Foundation pregnancy guidance.
Machamba AAL, Azevedo FM, Fracalossi KO, Franceschini SCC · 2021 · Arch Endocrinol Metab · PMID 34191411
Finding: Systematic review of iodine supplementation in pregnancy in mild-to-moderate iodine-deficiency areas. Maximum supplementation 300 µg/day potassium iodide. No significant improvement in children's mental development index or behavioural development index in supplemented groups; the psychomotor development index (PDI) showed improvement for poorer gross motor skills. Differences in response time to sound in mild-deficiency-area supplementation.
Relevance: The most recent systematic review of pregnancy iodine supplementation in mild-deficiency settings — modest psychomotor signal, no clear cognitive signal in the intervention literature. Highlights the gap between observational pregnancy-cognition associations (Bath 2013) and the smaller interventional evidence base.
Systematic reviews
- pmid:34191411
Machamba 2021 Arch Endocrinol Metab — 4 RCTs + 4 cohorts, pregnancy iodine supplementation in mild-to- moderate deficiency areas. Modest psychomotor signal in PDI; no clear mental-development or behavioural- development effect. Further studies needed.
Evidence quality summary
Severe iodine deficiency in pregnancy and intellectual disability — HIGH certainty (decades of observational and ecological evidence in iodine-deficiency settings). Mild UK maternal iodine deficiency and offspring verbal IQ + reading — MODERATE certainty (Bath 2013 PMID 23706508 UK cohort signal). Pregnancy iodine supplementation for cognitive endpoints in mild deficiency — LIMITED certainty (Machamba 2021 PMID 34191411 systematic review). Iodine supplementation in iodine-replete adults — INSUFFICIENT benefit signal, with thyroid dysfunction risk in susceptible individuals. Six UK Article 13.1 thyroid + cognitive + skin + metabolism + nervous-system function claims — HIGH mechanism certainty.
Known gaps
- UK-specific RCT of pregnancy iodine supplementation with offspring cognitive endpoints (the Bath 2013 ALSPAC signal needs interventional confirmation).
- Effectiveness of UK pregnancy multivitamin iodine inclusion (150 µg/day potassium iodide) on actual maternal urinary iodine status and offspring outcomes — observational data exists, RCT data does not.
- Long-term safety data on UK iodine-fortified plant drinks (variable across brands, contribution to total intake unclear).
- Whether UK salt iodisation policy (not currently in place) would shift the population deficiency profile — modelling exists, policy decision pending.
- Kelp-supplement iodine-content variability and adverse-event burden in the UK — case reports exist but no systematic UK surveillance.
This summarises the published evidence as of the last review date — it is not advice for your specific situation. Talk to your pharmacist or GP.
Safety
Iodine sufficiency matters for thyroid function and (especially) foetal neurological development; both deficiency and excess produce thyroid dysfunction. Choose a controlled potassium iodide product over a kelp-based product, supplement at 100-150 µg/day for general adult use, and avoid supplementation entirely if you have diagnosed autoimmune thyroid disease without endocrinology input.
Talk to your pharmacist or GP first if you:
- You have diagnosed autoimmune thyroid disease (Hashimoto thyroiditis, Graves' disease, postpartum thyroiditis) — endocrinology input first.
- You have a thyroid nodule or multinodular goitre — endocrinology input first.
- You take levothyroxine — separate iodine doses by ≥2 hours; routine iodine supplementation may affect thyroid replacement requirement.
- You take an antithyroid medication (carbimazole, propylthiouracil) — iodine opposes the action; do not supplement.
- You take lithium — additive hypothyroid effect; monitor thyroid function.
- You take amiodarone — high baseline iodine load already; do not stack iodine supplements.
- You are pregnant or breastfeeding — meet the 200 µg/day RNI from diet plus a 150 µg pregnancy multivitamin where dietary intake is low.
- You have iodine allergy or shellfish allergy — distinct conditions but cross-reactivity is a question worth discussing with a pharmacist; iodine itself rarely causes allergy.
Common side effects: Generally well-tolerated at standard supplement doses. Metallic taste, increased salivation, GI upset at high doses. Thyroid dysfunction (hyper- or hypo-) at sustained excess intake or in susceptible individuals.
Pregnancy and breastfeeding
UK pregnancy RNI is 200 µg/day. Routine UK pregnancy multivitamins typically include 150 µg potassium iodide to cover the gap above non-pregnant adult RNI of 140 µg/day. Avoid kelp-based iodine supplements in pregnancy — iodine- content variability is the load-bearing safety issue. Severe iodine deficiency in pregnancy is the leading preventable cause of intellectual disability worldwide; UK iodine status sits in the mild-deficiency band for significant fractions of pregnant women per Bath 2013 ALSPAC analysis (PMID 23706508) — children of mothers with first-trimester urinary iodine <150 µg/g creatinine had higher odds of lowest-quartile verbal IQ + reading at age 8. Talk to your midwife before adding any iodine supplement.
UK lactation RNI is 200 µg/day. Iodine concentrates in breast milk; sustained low maternal intake during prolonged exclusive breastfeeding can produce neonatal iodine insufficiency. Talk to your midwife or health visitor if your dietary intake is low (vegan, no dairy, no white fish).
Talk to your GP, midwife, or pharmacist before starting any supplement during pregnancy or breastfeeding.
More clinical detail (for clinicians and informed readers)
Contraindications
- Concurrent antithyroid medication (carbimazole, propylthiouracil).
- Concurrent amiodarone (already very high iodine load).
- Diagnosed autoimmune thyroid disease without endocrinology input.
- Autonomous thyroid nodules / multinodular goitre without endocrinology input.
- Hypersensitivity to iodine (rare).
Drug interactions
Antithyroid medication (carbimazole, propylthiouracil) · high
Effect: Pharmacodynamic opposition — antithyroid drugs work by blocking thyroid hormone synthesis; iodine provides the substrate. Supplementing iodine reduces the antithyroid drug's effect and can destabilise control of hyperthyroidism.
Mechanism: Antithyroid drugs (carbimazole, propylthiouracil) inhibit thyroid peroxidase, the enzyme that incorporates iodine into thyroglobulin. Supplemental iodine drives more substrate into the pathway, partially overcoming the antithyroid blockade.
Action: Do NOT self-supplement iodine while on antithyroid medication. Tell your endocrinology team or specialist prescriber about any iodine-containing supplement (including kelp, seaweed, multivitamins with iodine).
Source: BNF carbimazole + propylthiouracil; UK NICE CKS Hyperthyroidism
Amiodarone (cardiac antiarrhythmic) · high
Effect: Amiodarone is approximately 37% iodine by weight and delivers an enormous iodine load (a typical 200 mg daily dose contains ~75 mg iodine, roughly 125 times the EFSA upper intake). Additional iodine supplementation on top of amiodarone is not advised — risk of iodine-induced thyroid dysfunction (hyper- or hypothyroidism, both recognised amiodarone adverse effects).
Mechanism: Amiodarone provides massive iodine excess; thyroid function is already perturbed in many amiodarone-treated patients. Adding iodine compounds the load.
Action: Do NOT add iodine supplements if you take amiodarone. Tell your cardiology team or specialist prescriber about any supplement use. Routine thyroid-function-test monitoring is standard on amiodarone therapy.
Source: BNF amiodarone; UK NICE CKS Hyperthyroidism + Hypothyroidism
Lithium (bipolar disorder, treatment-resistant depression) · medium
Effect: Lithium reduces thyroid hormone release from the gland and is associated with hypothyroidism in 5-15% of long-term users. Adding iodine in this context is complicated — modest top-up may be appropriate for documented iodine deficiency, but additive hypothyroidism risk warrants prescriber input.
Mechanism: Lithium inhibits thyroid hormone release and increases intra-thyroidal iodine content. The mechanisms of lithium-induced hypothyroidism and iodine-induced hypothyroidism overlap.
Action: Tell your psychiatrist or prescriber if you take lithium and want to add iodine. Thyroid-function testing should be monitored more frequently while combining the two.
Source: BNF lithium carbonate; UK NICE CG185 Bipolar disorder
Levothyroxine (thyroid hormone replacement) — separate iodine doses by ≥2 hours from levothyroxine. Routine iodine supplementation may affect thyroid replacement requirement; TFT monitoring is appropriate.
Potassium-sparing diuretics (spironolactone, eplerenone), ACE inhibitors, ARBs — potassium iodide adds a small potassium load; clinically significant only at high doses or in renal impairment.
Iodinated radiology contrast — separate clinical context; iodine-allergic patients should disclose to radiology.
Tell your prescriber if you take any of these combinations. This is not personalised advice.
This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.
Common side effects
- Generally well-tolerated at 100-200 µg/day in healthy adults.
- Metallic taste, increased salivation, mild GI upset at high doses.
Rare side effects
- Iodine-induced hyperthyroidism (Jod-Basedow) — autonomous nodules, undiagnosed Graves' disease, or sudden iodine load in iodine-deficient adult.
- Iodine-induced hypothyroidism — sustained excess intake, autoimmune-prone individuals (failure to escape Wolff-Chaikoff).
- Thyroiditis flare — Hashimoto-prone individuals.
- Iodine sensitivity reactions (rare, mostly with iodinated radiology contrast not dietary iodine).
- Acneiform eruption ("ioderma") — sustained high-dose intake, very rare.
How to take it
- Typical supplemental range
- Standard UK supplement dose is 100-150 µg/day potassium iodide for general supplementation, or 150 µg/day for pregnancy. NHS pathways for iodine deficiency in adults manage at the 150-200 µg/day range. High-dose clinical iodine preparations (Lugol's, KI tablets in nuclear emergency) are prescriber-supervised and not part of food-supplement context.
- Timing
- Daily — any time of day. Iodine half-life and thyroid storage capacity make day-to-day timing flexible. Separate by ≥2 hours from levothyroxine if both are taken (reduces interaction at gut absorption).
How to spot quality
Look for
- Form declared (potassium iodide is the standard, predictable form; potassium iodate also acceptable; sodium iodide less common).
- µg per serving stated explicitly — not just "% NRV".
- For kelp-source products: declared iodine content per serving with per-batch testing — without this, the product is not suitable as a controlled iodine source.
- GMP-certified manufacture.
- For pregnancy multivitamins: 150 µg/day potassium iodide is the standard inclusion.
Red flags
- Kelp-based iodine supplement without declared iodine content per serving — variable batches mean variable doses.
- Iodine doses above 600 µg/day for general adult supplementation — outside EFSA UL.
- Marketing iodine for "breast health" / "fibrocystic breast disease" without clinician oversight — outside UK NHS pathway.
- Marketing iodine for "thyroid boost" / "thyroid support" / "metabolism boost" in iodine-replete users — outside trial evidence and outside the dose range delivering benefit without harm.
- Iodine in the same supplement as kelp without combined-iodine-content declaration — possible double-dosing.
- No EFSA-UL warning on high-dose iodine products.
Commonly combined with
Other ingredients that share a biological pathway, cofactor relationship, or evidence-backed protocol with this one. Mechanisms below cite primary physiology — not folk pairing. Doses are literature ranges, not recommendations. Talk to your pharmacist or GP before changing your stack, especially if you take prescription medication.
Selenium
Moderate evidenceThe canonical thyroid-cluster pairing — iodine is the substrate for thyroid hormone synthesis; selenium is the cofactor for the deiodinase enzymes that activate the hormone in peripheral tissues.
Iodine is incorporated into thyroglobulin in the thyroid follicle to form T4 and (to a lesser extent) T3. Most circulating T3 — the more biologically active thyroid hormone — is generated in peripheral tissues by deiodinase enzymes (DIO1, DIO2, DIO3) that remove a specific iodine atom from T4. The deiodinases are SELENOPROTEINS — they require a selenocysteine residue at their active site. Adequate selenium status is therefore required for full thyroid hormone activation; selenium deficiency reduces T4-to-T3 conversion even when iodine intake is adequate.
The pairing is also relevant to autoimmune thyroid disease. Selenium supplementation has been studied in Hashimoto thyroiditis with reductions in anti-thyroid-peroxidase antibody titres in some trials (Toulis 2010 meta-analysis) — though hard clinical-endpoint evidence is mixed and UK NICE pathways do not routinely include selenium for autoimmune thyroiditis.
Mechanism-wise the iodine-selenium pairing is robust. Trial-evidence-wise the case for combined supplementation is moderate for thyroid biomarker support, limited for hard clinical endpoints. UK Article 13.1 authorised claims for both: iodine "contributes to the normal production of thyroid hormones and normal thyroid function"; selenium "contributes to the normal thyroid function".
Evidence: Mechanism (selenoprotein deiodinases) is well-established. UK Article 13.1 thyroid claims authorised for both. Hashimoto antibody-titre trial evidence (Toulis 2010 meta-analysis) supportive but not in UK NICE pathway. [7]
Doses studied: 150 µg/day potassium iodide with 100-200 µg/day L-selenomethionine. NB-550 Selenium L-Selenomethionine covers the selenium component.
Found in Camden: Purifera™ Selenium 200µg L-Selenomethionine 120 Capsules
Methyl Folate (5-Methyltetrahydrofolate)
Strong evidencePreconception supplement bundle — iodine alongside folate, vitamin D, and iron is the UK pregnancy supplement profile.
The UK preconception supplement bundle is grounded in three distinct mechanisms each addressing a separate pregnancy outcome: folate (400 µg/day) for neural tube defect prevention (closure occurs by week 4-6, often before pregnancy is recognised); vitamin D3 (10 µg/day) for foetal calcium homeostasis and bone development; iodine (150 µg/day, total intake target 200 µg/day) for foetal neurological development via maternal-foetal thyroid hormone transfer. Iron is added where dietary intake is low or anaemia is present.
None of these acts on the others mechanistically — each addresses a separate developmental axis. The pairing is bundled because pregnancy planning is the right life stage to attend to all three simultaneously; supplements that include all three (UK pregnancy multivitamins) match the bundle.
Evidence: RCOG Green-top 23 / NHS pregnancy supplement guidance / British Thyroid Foundation pregnancy iodine guidance all support the bundle. [2]
Doses studied: Pregnancy multivitamin: 400 µg/day folate (or methyl-folate for MTHFR-variant women) + 10 µg/day vitamin D3 + 150 µg/day potassium iodide. Some include 14 µg/day iron, particularly for women with confirmed iron-deficiency anaemia.
Zinc
Limited evidenceIodine, selenium, and zinc are the three trace-mineral inputs to thyroid hormone synthesis and signalling. Zinc plays a smaller role than selenium but features in some thyroid-cluster formulations.
Zinc is required for the function of thyrotropin-releasing hormone (TRH) signalling and for thyroid hormone receptor binding to DNA at the nuclear thyroid hormone response elements. Zinc deficiency has been associated in some populations with reduced T3 levels and impaired thyroid hormone action, though the effect is more modest than selenium deficiency.
The iodine-selenium-zinc thyroid trio appears in some pregnancy multivitamins and in dedicated thyroid-support products. The mechanism is supportive — adequate zinc status enables normal thyroid hormone signalling — rather than synergistic. UK Article 13.1 claim wording for zinc does NOT include thyroid (zinc claims cover cognitive function, immune system, protein and DNA synthesis, testosterone maintenance, fertility, acid-base / carbohydrate metabolism).
Evidence: Mechanism (zinc role in thyroid hormone receptor and TRH signalling) is established. Direct trial evidence for combined iodine-zinc supplementation is limited. UK Article 13.1 claims for zinc do not include thyroid wording. [7]
Doses studied: 150 µg/day iodine with 10-15 mg/day zinc citrate or zinc picolinate. Most UK general multivitamins include both at NRV-equivalent doses.
Kelp (brown seaweed)
Insufficient evidenceThyroid-cluster — kelp is a natural iodine source but with extreme variability; Camden iodine is the canonical safety reference.
Kelp species (Laminaria, Saccharina, Ascophyllum, Fucus) deliver 100-8000 µg iodine per gram of dried herb. Variability is the load-bearing safety issue. Camden iodine addresses this in detail.
Evidence: Camden iodine covers safety + thyroid cluster.
Doses studied: Avoid kelp as a controlled iodine source — use 100-150 µg potassium iodide instead.
Sea Moss (Chondrus crispus / Eucheuma cottonii)
Insufficient evidenceIodine-source cluster — sea moss has variable iodine content; same safety concern as kelp.
Sea moss iodine content varies by species and harvest; same uncontrolled-iodine-delivery issue as kelp. Camden iodine + kelp cover safety.
Evidence: Camden iodine + kelp cluster.
Doses studied: Avoid sea moss as a controlled iodine source.
Verifera™ editorial perspective
Why it matters. Iodine is one of the most consequential and most-underrated UK public-health nutrient gaps — the Vanderpump 2011 Lancet survey (PMID 21640375) and Bath 2013 Lancet ALSPAC analysis (PMID 23706508) together establish that the UK sits in the mild-deficiency band by WHO criteria, and that this matters for foetal cognitive development. Yet UK NHS pregnancy supplement guidance still does not list iodine as a routine addition to the folic-acid + vitamin-D bundle.
Where Camden lands. Camden Medicals does NOT currently retail a single-active iodine SKU. The entry serves as the molecular and regulatory pillar for Camden's selenium SKU (NB-550, the canonical iodine-selenium thyroid-cluster pairing) and as the load-bearing safety reference for "why kelp is not a controlled iodine source". For pregnant women and women planning pregnancy, the right tier is a UK pregnancy multivitamin that includes 150 µg/day potassium iodide alongside the folic-acid + vitamin-D bundle.
If you want to explore further. Audit your dietary iodine first. A 200 ml glass of cow's milk delivers 30-50 µg; a portion of cod or haddock 100-300 µg; an egg ~25 µg. Most UK adults who consume dairy and eggs meet the 140 µg/day RNI from food. If you are pregnant, planning pregnancy, vegan, or dairy-avoidant, talk to your midwife or GP about a 100-150 µg/day potassium iodide supplement (or an iodine-fortified plant drink). If you have diagnosed thyroid disease or take levothyroxine, antithyroid medication, amiodarone, or lithium, do NOT self-supplement — talk to the endocrinology team or specialist prescriber.
How this entry was researched
Authoritative sources consulted:
- NHS Iodine page + Pregnancy: vitamins, supplements and nutrition page
- NICE CKS Hypothyroidism + Hyperthyroidism
- British Thyroid Foundation pregnancy iodine guidance
- British Dietetic Association iodine food fact sheet + position paper (2018, updated 2021)
- RCOG Green-top 23 supplement-in-pregnancy framework
- WHO/UNICEF/IGN iodine sufficiency criteria (urinary iodine concentration thresholds)
- GB Nutrition and Health Claims (NHC) Register — six Article 13.1 authorised iodine claims + growth-of-children claim
- National Diet and Nutrition Survey (NDNS) rolling programme
- PubMed (via E-utilities MCP, 2026-05-12)
PubMed search terms:
Vanderpump iodine UK schoolgirls Lancet 2011 surveyBath iodine pregnancy ALSPAC child IQ verbal Lancet 2013iodine pregnancy supplementation systematic review cognition offspring
Literature search date: 2026-05-12
Sources listed are those consulted by the Verifera™ editorial team. Readers should verify against current authoritative sources.