Thyroid

Nutrients connected to Thyroid

A link means the body needs the nutrient for this, or that low intake is linked to it. It does not mean extra supplements help if your intake is already adequate; each link shows how strong the evidence is.

• IodineEstablished role

  The thyroid gland takes up iodine to make its hormones. Low intake can enlarge it (goiter); too much can disturb it.

• BladderwrackDocumented risk

  Bladderwrack is rich in iodine; the EU herbal committee concluded it can influence thyroid function, and a trial of kelp capsules raised TSH. People with thyroid disease should ask a clinician first.

• BugleweedPreliminary or mixed

  Its main studied target. It may reduce thyroid activity and can interfere with thyroid medicines and isotope tests (consumer references).

• Irish moss (sea moss)Documented risk

  The thyroid takes up iodine; excess seaweed iodine can suppress or disturb it, including in breastfed infants.

• KelpDocumented risk

  Kelp can supply very large amounts of iodine, and too much iodine can make the thyroid underactive or overactive. A case report describes a temporary overactive thyroid after kelp tablets.

• KombuDocumented risk

  Kombu has so much iodine that it can push intake past the upper limit, which can disturb the thyroid. Ask a clinician if you have a thyroid condition.

• WakameDocumented risk

  Excess iodine from seaweed can cause overactive or underactive thyroid in some people; people with thyroid disease are more susceptible.

• DulseDocumented risk

  Dulse is high in iodine and the amount varies by season. Too much iodine can disturb the thyroid; people with thyroid disease should ask their clinician.

• Sea Moss (Eucheuma & Gracilaria)Documented risk

  Too much iodine from seaweed can disturb the thyroid. No measured iodine value for sea moss itself was found, so the amount in a product is unknown unless tested.

• Sea LettuceDocumented risk

  Dried sea lettuce is a notable iodine source per gram. Too much iodine can change how the thyroid works; ask a clinician if you have thyroid disease. This is about excess, not thyroid support.

• Ao-nori (Green Laver)Documented risk

  Dried ao-nori is a notable iodine source per gram. Too much iodine can change how the thyroid works; ask a clinician if you have thyroid disease. This is about excess, not thyroid support.

• Kelp NoodlesDocumented risk

  Kelp can contain a lot of iodine, which in excess may change thyroid function. The amount in kelp noodles varies by product, so people with thyroid conditions should ask a clinician.

• Seaweed Snacks (Roasted Nori)Documented risk

  Snack iodine per serving can pass upper limits, especially for young children; thyroid effects follow high long-term iodine (NHS).

• Dashi (Kombu Stock)Documented risk

  Kombu stock can carry a large amount of iodine, which can disturb the thyroid if intake is high. Ask a clinician if you have a thyroid condition.

• Iodized Table SaltEstablished role

  Iodine is needed to make thyroid hormones; too little can cause goiter and too much can disturb thyroid function.

• SeleniumEstablished role

  Selenium is needed for thyroid hormone production; in Hashimoto thyroiditis, trials show lower TSH and antibody markers.

• AshwagandhaDocumented risk

  Case reports describe thyrotoxicosis after use, and NCCIH advises caution in thyroid disorders and with thyroid hormone medicines.

• Self-healPreliminary or mixed

  Studied as an add-on to thyroid drugs for overactive thyroid and nodules; evidence is low quality.

• Ashwagandha TeaDocumented risk

  Thyrotoxicosis case reports; may raise thyroxine on tests.

• ArameDocumented risk

  Arame contains iodine (about 79 mg per kg in one sample); too much iodine can change how the thyroid works.

• HijikiDocumented risk

  Hijiki carries a lot of iodine (Korean average about 527 mg per kg dry weight). Too much iodine can change how the thyroid works.

• MozukuDocumented risk

  Excess iodine from seaweed has been linked to hyperthyroidism, thyroiditis and goiter. Mozuku's own iodine is unknown.

• Nori (Laver)Documented risk

  Nori is lower in iodine than kombu, but seaweed iodine can affect the thyroid at high intakes, and nori products vary widely.

• Seaweed SaltDocumented risk

  Seaweed such as kelp can hold very high iodine, and excess iodine can affect the thyroid. How much a seaweed salt holds was not found.

• Seaweed Salad (Chuka Wakame)Documented risk

  Excess iodine can harm the thyroid in susceptible people.

• Bone Health FormulasDocumented risk

  Thyroid medicine may be absorbed less when taken close to calcium; spacing is advised.

• Greens PowdersDocumented risk

  Seaweed ingredients such as kelp add an iodine question for the thyroid; ask a clinician if you have a thyroid condition.

• CarnitineDocumented risk

  In one trial in women taking thyroid hormone, L-carnitine reduced hyperthyroid-type symptoms, suggesting it can work against thyroid medicine. Do not change medicine without asking a prescriber.

• Yerba mateDocumented risk

  The EU monograph lists overactive thyroid (hyperthyroidism) as a contraindication. No further detail was given.

• KaleDocumented risk

  Goitrogens in kale matter mainly in large amounts or with low iodine, per the Linus Pauling Institute.

• Collard GreensDocumented risk

  Cabbage-family vegetables contain goitrogens that matter mainly at large intakes with low iodine; no human trial on collards was found.

• Mustard GreensDocumented risk

  Goitrogens in cruciferous vegetables matter mainly in large amounts or with low iodine intake.

• BroccoliPreliminary or mixed

  A 2024 systematic review found no adverse effect of brassica vegetables on thyroid function in humans with adequate iodine; people with thyroid disease should ask their clinician.

• Jamun (Java plum seed)Documented risk

  A seed isolate disturbed thyroid hormones in pregnant rats; human relevance unknown.

• CauliflowerPreliminary or mixed

  Cauliflower contains goitrogen precursors; a 2024 review found no adverse effect on thyroid function from daily intake with adequate iodine. Ask a clinician if you have thyroid disease.

• CabbageDocumented risk

  Glucosinolate breakdown products can reduce thyroid iodine uptake in theory; the evidence in people does not show harm with adequate iodine.

• Bok ChoyDocumented risk

  One case report of myxedema coma after raw bok choy (title only read); review of 123 studies found no harm in usual diets with enough iodine.

• RadishesDocumented risk

  Raw cruciferous vegetables contain goitrogens; a 2024 systematic review found most evidence does not support harm to thyroid function in people, especially with adequate iodine.

• Daikon RadishDocumented risk

  Goitrogens can interfere with iodine use; not of clinical importance unless intake is large or iodine is low.

• TurnipsDocumented risk

  Glucosinolate breakdown products can lower thyroid iodine uptake in high amounts, but turnip tops are low in goitrin and reviews find no harm at food intakes with enough iodine.

• KohlrabiDocumented risk

  Very high intakes of some crucifers affected the thyroid in animals; risk appears linked to low iodine, not normal food amounts.

• Cassava (Yuca)Documented risk

  Thiocyanate from cassava cyanide can interfere with iodine uptake by the thyroid, mainly where iodine is deficient.

• Lemon Balm TeaDocumented risk

  Possible TSH inhibition from a water extract (lab and animal data); ask a clinician if you have a thyroid condition.

• Yerba MateDocumented risk

  The EU monograph lists an overactive thyroid as a reason not to use mate.

• FucoidanDocumented risk

  Iodine in kelp-derived products; excess iodine can affect the thyroid.

• FucoxanthinDocumented risk

  Brown seaweed can carry very high iodine, which can affect the thyroid. No iodine data were found for purified fucoxanthin, so check any seaweed-based product.

• Sea Salt, Himalayan Salt and Dead Sea Salt: Mineral ClaimsDeficiency link

  Iodized salt exists to prevent goiter; not every salt is iodized.

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