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Vitamins and minerals

Iodine and the thyroid — too much or too little?

Sources: 10 · Article: 13 266 characters

Andrzej Frydrychowski describes iodine deficiency as common and recommends kelp, which contains a lot of iodine.

  • Henryk Różański explains that iodine is involved in the production of the thyroid hormones T3 and T4.
  • People with hypothyroidism should be careful with cruciferous vegetables and make sure they get enough iodine in their diet.
  • Jerzy Zięba recommends combining iodine supplementation with an adequate intake of selenium.
  • Jerzy Jaśkowski warns that giving iodine in the event of a radioactive threat outside the recommended time is harmful.

What the authors write

Henryk Różański

Iodine binds to tyrosine and is involved in the production of the thyroid hormones T3 and T4.

„One iodine atom binds to one tyrosine molecule, producing monoiodotyrosine (MIT). When it binds two iodine atoms, it becomes diiodotyrosine (DIT). Peroxidase is responsible for the intramolecular restructuring of thyroglobulin, during which two molecules of diiodotyrosine produce thyroxine (tetraiodothyronine).”Jeden atom jodu wiąże się z jedną cząsteczką tyrozyny, dając monojodotyrozynę (MIT). Gdy zwiąże dwa atomy jodu przekształca się w dijodotyrozynę (DIT). Peroksydaza odpowiedzialna jest za wewnątrzcząsteczkową przebudowę struktury tyreoglobuliny, podczas której z dwóch cząsteczek dijotyrozyny powstaje tyroksyna (tetrajodotyronina).
Choroba Hashimoto, czyli przewlekłe autoimmunologiczne zapalenie tarczycy, część 1.
Henryk Różański

The thyroid takes up iodine, and follicle cells transport it using iodine pumps.

„At the same time, the thyroid has the ability to absorb iodine. Iodine is taken up by the epithelial cells of the follicles. Iodine pumps are built into their membranes and transport iodine. The same cells contain an enzyme—peroxidase—which oxidizes iodine ions into elemental iodine:”Jednocześnie tarczyca ma zdolność pochłaniania jodu. Jod jest wychwytywany przez komórki nabłonka pęcherzyków. W ich błony wbudowane są pomy jodowe, transportujące jod. W tych samych komórkach znajduje się enzym – peroksydaza, która utlenia jony jodu do jodu pierwiastkowego:
Choroba Hashimoto, czyli przewlekłe autoimmunologiczne zapalenie tarczycy, część 1.
Andrzej Frydrychowski

Andrzej Frydrychowski describes iodine deficiency as common and recommends kelp as a product containing a lot of iodine.

„Iodine deficiency, so common in our population, has a negative effect on our cardiovascular system. Iodine stabilizes the heart rhythm, lowers blood pressure, and makes the blood thinner. If we do not want to use Lugol's solution, we should at least add kelp to our diet (brown seaweed that contains a lot of iodine).”Niedobór jodu, tak częsty w naszej populacji, wpływa negatywnie na nasz układ sercowo-naczyniowy. Jod stabilizuje rytm serca, obniża ciśnienie tętnicze i sprawia, że krew jest bardziej rozrzedzona. Jeśli nie chcemy stosować płynu Lugola, to chociaż wprowadźmy do naszej diety Kelp (brunatne algi morskie, które zawierają dużo jodu).
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Henryk Różański

Some compounds in cruciferous plants make it harder for iodine to bind, and people with hypothyroidism should be careful about consuming them.

„On the one hand, they have antiseptic and antibacterial effects, inhibit the development of some cancers, and have an anti-atherosclerotic effect; on the other hand, some of them prevent iodine from binding to the amino acids in thyroid hormones. As a result, the level of active thyroxine falls, hypothyroidism develops, and further consequences follow.”Z jednej strony działają one odkażająco, przeciwbakteryjnie, hamują rozwój niektórych nowotworów, wywierają wpływ przeciwmiażdżycowy, z drugiej jednak strony – niektóre z nich uniemożliwiają wiązanie jodu przez aminokwasy hormonów tarczycy. Spada przez to poziom aktywnej tyroksyny, następuje niedoczynność tarczycy i dalsze tego następstwa.
Rośliny krzyżowe Cruciferae a tarczyca
Henryk Różański

When eating cruciferous vegetables, Henryk Różański recommends making sure there is enough iodine in the diet.

„If someone likes cruciferous vegetables, they should make sure their diet provides enough iodine to prevent the potential side effects of impaired iodination of tyrosine and thyronine in the thyroid. Head cabbage – Brassica oleracea varium capitata (L.) Alef., Wolsztyn, July 2008.”Jeżeli ktoś lub warzywa kapustne powinien zadbać o dostateczną podaż jodu w diecie, aby zapobiec potencjalnym skutkom ubocznym zaburzonego jodowania tyrozyny i tyroniny w tarczycy. Kapusta głowiasta – Brassica oleracea varium capitata (L.) Alef., Wolsztyn, lipiec 2008 r.
Rośliny krzyżowe Cruciferae a tarczyca
Jerzy Zięba

Jerzy Zięba emphasizes that iodine supplementation increases the amount of raw material available for hormone production and should be combined with an adequate intake of selenium.

„Thanks to selenium, excess of this compound is continuously removed, so the thyroid is not damaged as a result of its normal activity. Iodine supplementation increases the availability of the substrate for hormone production, so it must go hand in hand with an adequate intake of selenium.”Dzięki selenowi nadmiar tego związku jest na bieżąco usuwany, tarczyca nie ulega zatem uszkodzeniu w wyniku swojej fizjologicznej aktywności. Suplementacja jodem zwiększa dostępność substratu do produkcji hormonów, z tego powodu musi iść w parze z dostateczną podażą selenu.
Minerał, który każdemu mężczyźnie uratuje… ☺ Jerzy Zięba
Jerzy Jaśkowski

Jerzy Jaśkowski warns that giving iodine in the event of a radioactive threat outside the recommended time is harmful.

„Iodine should be given only 24 hours before the radioactive cloud arrives and no later than 12 hours after it arrives. Giving it earlier or later is harmful. In Łódź, however, it was given a month later, which meant poisoning children. WHO says that iodine may be given when the expected radiation dose will be at least”Jod wolno podać jedynie 24 godziny przed nadejściem chmury radioaktywnej i najpóźniej 12 godzin po jej przyjściu. Wcześniej i później jest to szkodliwe. A w Łodzi dawano go miesiąc po, czyli truto dzieci. WHO twierdzi, że jod wolno podać, gdy spodziewana dawka promieniowania będzie wynosiła min.
Niedoczynność tarczycy
Jerzy Jaśkowski

Jerzy Jaśkowski asks why iodine levels are not tested when similar symptoms occur.

„If it is known that the same symptoms occur with the deficiencies mentioned above, why are tests—for example, iodine levels—not carried out? It was once said that salt is iodized as part of the effort to fight iodine deficiency, but that cannot be true, because, for example, there is enough iodine on the coast.”Jeżeli wiadomo, że te same objawy występują przy wyżej wymienionych niedoborach to dlaczego nie wykonuje się badań np. poziomu jodu? Mówiono kiedyś, że sól jest jodowana w ramach walki z niedoborem jodu, ale nie może być to prawdą, bo np. na wybrzeżu jest wystarczająca ilość jodu.
Niedoczynność tarczycy
Jerzy Jaśkowski

Jerzy Jaśkowski lists iodine deficiency as one of the deficiencies that can cause symptoms similar to those of hypothyroidism.

„This diagnosis is being made more and more often and more quickly. Whether it is justified is debatable, because the same symptoms as those of hypothyroidism also occur with deficiencies of iron, selenium, vitamin D, and iodine. It is surprising that our endocrinologists, citing supposed NFZ procedures, do not order these basic tests for people suspected of having the disease.”Jest to coraz częściej i szybciej stawiana diagnoza, czy słusznie – kwestia wątpliwa, ponieważ te same objawy, jakie są przy niedoczynności tarczycy, występują też przy niedoborze żelaza, selenu, witaminy D i jodu. Zdziwienie budzi to, że nasi endokrynolodzy, zasłaniając się rzekomo procedurami NFZ, nie zlecają tych podstawowych badań osobom podejrzanym o chorobę.
Niedoczynność tarczycy

Research from PubMed · Europe PMC

We selected 5 studies with the best, positive results. This is a selection, not a full review of all research.

Total number of studies on this topic in PubMed: 545.

A meta-analysis found that an adequate iodine intake may be associated with a lower risk of papillary thyroid cancer, while excess iodine may be associated with a higher risk.

Aim of the study: The effect of iodine on papillary thyroid cancer (PTC) has been controversial for many years. Since urinary iodine is an effective indicator of iodine intake, some recent epidemiological studies have described the relationship between urinary iodine concentration (UIC) and PTC.

Results: According to the analysis of the included studies, excessive iodine intake (UIC≥300ug/L) was positively associated with the occurrence of PTC patients compared with healthy controls (OR4.05, 95%CI 1.64-10.02, P=0.002). Meanwhile, adequate iodine exposure (100≤UIC<200ug/L) may play a protective role in the occurrence of PTC compared with healthy individuals (OR 0.36, 95%CI 0.14-0.91, P=0.03) while the difference in the prevalence of insufficient iodine intake (UIC<100ug/L) and iodine above requirements (200≤UIC<300ug/L) among the two groups were not significant (deficiency: OR 0.38, 95%CI 0.13-1.16, P=0.09; above requirements: OR 0.92, 95%CI 0.40-2.10, P=0.84).

The relationship between urinary iodine concentration and papillary thyroid cancer: A systematic review and meta-analysis. · Front Endocrinol (Lausanne) 2022
Money for the studygovernment, public institutions · The Research Fund for Public Welfare, National Health and Family Planning Commission of China, The Clinical Research Fund of Chinese Medical Association
Do the authors have ties to companies?no — the authors say so
Did a manufacturer help with the study?NO
Type of studycombined analysis of many studies (meta-analysis)

“Not stated” does not mean nobody paid — the database does not always record it.

A review indicates that an adequate iodine intake may help limit thyroid dysfunction, and iodized salt is an effective way to prevent iodine deficiency.

Aim of the study: Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected.

Results: In most countries, the best strategy to control iodine deficiency in populations is carefully monitored universal salt iodization, one of the most cost-effective ways to contribute to economic and social development. Achieving optimal iodine intakes from iodized salt (in the range of 150-250 microg/d for adults) may minimize the amount of thyroid dysfunction in populations. Ensuring adequate iodine status during parenteral nutrition has become important, particularly in preterm infants, as the use of povidone-iodine disinfectants has declined. Introduction of iodized salt to regions of chronic iodine deficiency may transiently increase the incidence of thyroid disorders, but overall, the relatively small risks of iodine excess are far outweighed by the substantial risks of iodine deficiency.

Iodine deficiency. · Endocr Rev 2009
Money for the studynot stated
Do the authors have ties to companies?not stated
Did a manufacturer help with the study?unknown
Type of studydiscussion of other studies

“Not stated” does not mean nobody paid — the database does not always record it.

In Nepal, universal salt iodization has greatly reduced iodine deficiency disorders, although the risk of iodine excess has also increased.

Aim of the study: Iodine deficiency is a major cause of thyroid disorders worldwide. Nepal lies in the endemic area of iodine deficiency which was previously referred to as Himalayan goiter belt, with high prevalence of iodine deficiency disorders including goiter, cretinism and hypothyroidism.

Results: With effective implementation of universal salt iodization program, Nepal has a successful public health story to share having drastically reduced the iodine deficiency disorders. Moreover, challenge has appeared with rising number of excess iodine states. Thyroid dysfunction is growing higher and the increasing proportion of hyperthyroidism is particularly concerning. Time has come for us to suitably review the standards of salt iodization and control the increasing number of cases with thyroid dysfunction by the coordinated efforts of all stakeholders, along with sustaining the optimal level of iodine.

Iodine deficiency and thyroid dysfunction: Current scenario in Nepal. · Ann Med Surg (Lond) 2022
Money for the studynot stated
Do the authors have ties to companies?no — the authors say so
Did a manufacturer help with the study?NO
Type of studyother

“Not stated” does not mean nobody paid — the database does not always record it.

A review concludes that an adequate amount of iodine supports normal body functions, while both deficiency and excess can harm the thyroid.

Aim of the study: Iodine is an essential micronutrient required for coordinating thyroid hormone synthesis, growth, neurodevelopment, metabolism, and immune function across humans and domesticated mammals. Molecular iodine can act as an antioxidant, anti-inflammatory, and anti-proliferative agent in several tissues, but these mechanistic effects require confirmation in well-designed human studies.

Results: Molecular iodine can act as an antioxidant, anti-inflammatory, and anti-proliferative agent in several tissues, but these mechanistic effects require confirmation in well-designed human studies. Recommended intakes fall within a narrow optimal range, reflecting a U-shaped response curve in which adequate intake supports systemic homeostasis, while both deficient and excessive intakes can impact immune function. Chronic deficiency impairs neurodevelopment and reproductive performance and weakens the host microbial defences, while sustained excess promotes oxidative stress, alters cytokine profiles, and in genetically susceptible individuals, increases the risk of subclinical or overt thyroid dysfunction and autoimmune thyroid disease.

Iodine and Its Impact on the Immune System of Humans and Domesticated Mammals: A Narrative Review. · Nutrients 2026
Money for the studynot stated
Do the authors have ties to companies?yes — the authors reported it
Did a manufacturer help with the study?YES
Type of studydiscussion of other studies

“Not stated” does not mean nobody paid — the database does not always record it.

A review indicates that iodine deficiency and excess can disrupt thyroid function, and that a sudden increase in intake after a period of deficiency may cause temporary hyperthyroidism.

Aim of the study: Severe iodine deficiency causes hypothyroidism that results in impaired somatic growth and motor development in children. Mild and moderate iodine deficiencies cause multifocal autonomous growth of thyroid, which results in thyrotoxicosis.

Results: In areas of iodine deficiency, a sudden increase in iodine intake is associated with transient hyperthyroidism. Recent studies demonstrated that long-term thyroid function of subjects who experienced both iodine deficiency and iodine excess during childhood tended to be abnormal despite optimization of their current iodine intake. Iodine status in the Korean Peninsula is very unique because people in the Republic of Korea have been shown to have predominantly excessive iodine levels, whereas the Democratic People's Republic of Korea is known to be an iodine-deficient area. Further research is warranted to verify the optimal ranges of iodine intake and to clarify the effects of iodine intake on thyroid disorders in the Korean Peninsula.

Iodine and thyroid function. · Ann Pediatr Endocrinol Metab 2014
Money for the studynot stated
Do the authors have ties to companies?no — the authors say so
Did a manufacturer help with the study?NO
Type of studydiscussion of other studies

“Not stated” does not mean nobody paid — the database does not always record it.

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