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Main diseases related to the Thyroid gland: HYPO OR HYPERTHYROIDIA - Are you deficient in iodine?(part 1)

Do you know that half of people with thyroiditis are not diagnosed. Indeed, because a mild or moderate case of hypothyroidism may not be detected during the analysis.
Overweight, fatigue, depression, memory problems ... According to OMS, the entire world population lacks 10% of the recommended iodine value. And you, are you deficient in iodine?
« It is impossible to have a balanced hormonal system without an adequate intake of Iodine. » ~ Dr Brownstein


Iodine is a mineral trace element necessary for the life and production of thyroid hormones T3 and T4. Iodine deficiency, prior to the 1920s, was the leading cause of hypothyroidism.

Since iodine was added to table salt- a practice born in Michigan in 1924 because of the many cases of hypothyroidism-this deficiency is rare in industrialized countries.

However, according to estimates by the World Health Organization, nearly 2 billion people are still at risk of iodine deficiency. This remains the number one cause of hypothyroidism in the world.

In industrialized countries where people are asked to limit salt intake, iodine deficiencies are omnipresent, since poorly informed people banish salt* instead of limiting it.


Iodine is a key trace element for the functioning of the thyroid gland. It is very important, because an inadequate intake is responsible for many ailments, such as cretinism, and excessive intake involves risks of goitre or hemorrhage.

This trace element is present in all tissues, but it is retained largely in the thyroid. Indeed, of the 25 to 50 mg contained in the body, 8 mg are concentrated in this endocrine gland located in the anterior part of the neck, under the apple of Adam.

The role of iodine is therefore intimately related to the activity of the thyroid.

Roles of Iodine

Iodine is a key trace element in the body. Its roles are multiple. It has an action on metabolism, digestion of carbohydrates and proteins, participates in the functioning of the heart and muscles, to fertility, …

Here are the main actions of iodine trace element:

  • Iodine is necessary for the production of thyroid hormones T3 and T4, which play a very important role in the regulation of cellular metabolism.
  • It intervenes in the basal metabolism (by stimulating the oxygen consumption) and consequently in the regulation of the temperature.
  • It has a role in the metabolism of carbohydrates, lipids and proteins.
  • Iodine has an action on the nervous system and therefore on the intellectual development.
  • It promotes normal functioning of the heart.
  • It promotes the development and functioning of the muscles.
  • The iodine trace element promotes the growth and maturation of the skeleton.
  • It is necessary for good fertility and stimulates lactation in breastfeeding women.
  • It has a positive action on the tegumentary system: skin, hair, nails …
  • It promotes gastrointestinal mobility and has an effect on the secreting activity of the digestive juices.

Daily requirement of iodine and excess

In an adult, the need is around 150 mg of iodine per day. These needs are normally met by a balanced diet. Depending on age and physiological activity, the RDI in Iodine changes. But beware, in case of excess (often due to medicines), the risks are important.


Daily iodine requirements are in the order of 120 to 150 mg / day in adults and 70 mg / day in children.

A normal diet is usually sufficient to cover the needs of our body in Iodine.

Summary table of recommended daily intakes of Iodine.

Age RDI in iodine in mg
Infants 0 to 1 year
Children 1 to 3 year
Children 4 to 10 year
Pregnant women
Breastfeeding women
40 to 50
70 to 100
RDI = Recommended Daily Intake (minimum Iodine dose to be consumed daily).


Iodine overload is also very common, but is rarely of food origin. This is most often a medicine overdose.

An excess of iodine intake can lead to hyperthyroidism or, on the contrary, the excess inhibits the synthesis of thyroid hormones and can therefore cause hypothyroidism.

An excessive presence of iodine or its derivatives, especially iodides, can also cause, in subjects with special susceptibility, what is called "iodism": this intoxication is characterized by mild intolerance symptoms ( Coryza, lacrimation, rash, salivation, pharyngitis, acne, purpura, various haemorrhages, tachycardia, headache, dizziness ...) or severe (glottis or lung edema).

The symptoms of an iodine overload are then the same as those described above, according to the triggered disease: hypo or hyperthyroidism.


Deficiency in trace element Iodine leads to hypothyroidism, which can be severe, with various effects, ranging from goitre to hallucinations, via cretinism and sterility. Fortunately, a lack of iodine is rare.

If the iodine deficiency is too high, goitre may be accompanied by hypothyroidism, the clinical signs of which are: psychomotor retardation (general fatigue, decreased memory), psychic disturbances (hallucinations, depressions) digestive disorders (constipation, loss of appetite or anorexia), muscle problems (cramps and myalgia), moderate anemia (due to lack of absorption of iron and vitamins B9 and B12), weight gain, cold intolerance, decreased ovarian function that can lead to sterility, irregular and abundant menstruation, decreased lactation, increased blood cholesterol and triglyceride levels, decreased heart rate and blood pressure…

In infants, there is a slowing or deficient development of the brain, or even mental retardation, retardation of growth, as well as a large tongue, constipation, inadequate proportions of the skeleton...

In the absence of an early and effective treatment, the evolution will be towards a dwarfism accompanied by a deep debility (cretinism).


Iodine is present in many foods. Sea salt is the main source of food in western societies because it is enriched with iodine. All seafood are good sources of iodine, as well as vegetables.

Iodine is predominantly found in iodinated sea salt.

But it is essential to look to other iodine-rich sources as new recommendations call for reducing the use of table salt in order to diminish cardiovascular risks due to over-consumption of salt (eg hypertension).

It is also found in crustaceans and other products coming from the sea: sea fish (cod, sardines, mackerel ...), algae, oysters and shellfish ... as well as in cod liver oil, meat, eggs, dairy products and certain cereals.

Mineral water and food such as leeks, watercress, spinach, green beans, turnips, onion, garlic, cabbage, carrots, radishes ....... have an iodine content which varies according to the iodine content of the soil on which it is harvested.

Monitoring iodine levels

Depending on diet, physical activity, age, medicines consumed or the physiological state (pregnant woman ...), the amount of Iodine necessary for the proper functioning of the body varies. It can then be interesting to treat its intake of Iodine to prevent any dysfunction.

In some people, or in some special situations, it is important to monitor the level of Iodine, to be certain that the amount of Iodine supplied to the body is sufficient.

The following people should monitor their intake of Iodine:

  • In pregnant and lactating women: any lack of iodine may cause mental retardation in the baby.
  • In postmenopausal women: because the thyroid gland very often experiences disruptions at this time. 1 in 5 women experiences thyroid dysfunction between 50 and 60 years, most often hypothyroidism.
  • In athletes: they appear to be more sensitive to iodine deficiency, which may be due to loss of sweat. Attention to the practice of a sports activity during high heat.
  • In infants.
  • In adolescents: because it is a period of great hormonal upheaval, where the thyroid function is strongly solicited.
  • In the elderly: because the thyroid gland also ages and the disorders become more frequent after 60 years.
  • In remote areas of the sea or in some countries, such as Japan, where the consumption of algae is very high and can cause an excess of iodine in the body, a frequent cause of hyperthyroidism.
  • In low-sodium diets (diets without salt).
  • In vegetarians: because they do not eat meat, fish and dairy that are important sources of iodine.
  • When taking medications: such as antiarrhythmics, lithium, contrast products and iodine-based disinfectants.
  • In smokers: because tobacco inhibits the absorption of iodine by the body.
  • In subjects who consume abundantly so-called "goitrogenic" foods, that is to say which can cause the appearance of goitre. This is the case of cabbage, broccoli, radish, etc. It is a situation that is rarely found in industrialized countries where food is diversified, but there are still places in the world where goitre is caused by a staple food.

Iodine: one more advice

Iodine does not work alone with the thyroid gland, it works in synergy with two antioxidant trace elements: zinc and selenium.

To produce thyroid hormones, the thyroid gland needs not only iodine, but also two other trace elements: zinc and selenium. If the organism is deficient in one of these three trace elements, there may be a slowing of the thyroid function.

* Sea water is naturally iodized, so sea salt contains iodine naturally. On the other hand, salt extracted from mines of salts (formerly evaporated seas) does not contain iodine. But it is an essential element in the good development of the human being, and the law obliges the table salt to be completed in iodine before the sale if it does not contain enough.

If iodine is lacking, the brain and thyroid gland develop badly.

That's why they say "cretin of the Alps". In the past, in the Alps, far from the sea and the shops, there were people who ate too little (not at all) of sea fish, sea salt or any other source of iodine, and they were "cretins" (people had deficiencies, and developed dwarfism, goitres and mental retardation.

Iodine is also given in the event of a nuclear accident because the organism confuses cesium and iodine and can fix cesium (radioactive) rather than iodine which is not nice for the tissues around (proven carcinogenic risk).

** Be aware that sea salt is not necessarily enriched with iodine. Make sure you choose which ones are.

Method for assessing iodine deficiencies or overloads!

Put tincture of iodine on a square of skin: as long as the body needs it, the brown stain, in principle, disappears quickly.
If the stain disappears in 24 hours, then there is a cruel lack of iodine; when the stain takes 5 days to be absorbed, the body has the iodine that suits it.
Continue until you have a total well being, and do the test on the skin from time to time.
However, this method is very empirical and the timing of the possible overload may not work for everyone.

Other symptoms may be considered when assessing iodine overload:

  • The excess of iodine can cause an exaggeration of the menstrual flow
  • Throat pain or runny nose without reason
  • Uncommon, excitement or other unusual symptom

Finally there are laboratory tests to measure the body's iodine load.

Next article:

Previous article:

Sources partie 1 et 2
Organisation mondiale de la santé. Demander à l’expert - La carence en iode peut-elle réellement provoquer des lésions cérébrales?, OMS.
Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism
Glinoer D, DeMayer P, Delange F. et al. 1995 « A randomized trial for the treatment of mild iodine deficiency during pregnancy: maternal and neonatal effects » J Clin Endocrinol Metab. 80:258–269.
Marine D, Kimball OP. (1922) « The prevention of simple goiter » Am J Med Sci. 163:34–39.
EPA, Comment-response summary report; Peer Review of Drinking Water Health Advisory for Perchlorate Contract No. EP-C-07-021 Work Assignment No. 1-06 Prepared for: U.S. Environmental Protection Agency Office of Water Office of Science and Technology Health and Ecological Criteria Division 301 Constitution Ave, N.W. Washington, D.C.2004
Joseph G. Hollowell et al. « Iodine Nutrition in the United States. Trends and Public Health Implications: Iodine Excretion Data from National Health and Nutrition Examination Surveys I and III (1971–1974 and 1988–1994) » JCEM, oct. 1998; 83 (10): 3401
Crétin des Alpes : origine de l'expression Proposé par Philippe le 20/01/2010 dans Expressions
J. Malcolm O. Arnold,Cardiologue, Hôpital Victoria, London, Ontario Professeur de médecine adjoint, University of Western Ontario. LE COEUR ET LA GLANDE THYROÏDE
Diabète et thyroïde, article paru sur le site internet de l’Hôpital universitaire Robert-Debré,

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