Iodine deficiency: what happened? And why is it serious?

iodine and diseases - comic

Goitre (or goiter) is a little ball formed at the bottom of the neck in people experiencing a high iodine deficiency. This is the swelling of the thyroid, trying to capture more iodine. But beyond this severe case, a moderated iodine deficiency, often invisible, can cause fatigue and trigger serious consequences on the body.

The lack of iodine intake from food is a problem that affects many countries (including Europe). To overcome this problem, the WHO had iodine added to table salt1 in order to increase the population intakes. Today, many people are still deficient (developed countries are not spared) and the consequences can be serious.

Nobody seems to really care about this subject, yet critical. Let’s educate ourselves!

The importance of iodine

Iodine and Thyroid

Iodine has a major role in the thyroid. Indeed, 70 to 80% of the body’s iodine is contained in the latter. Iodine is mainly used for the synthesis of the hormone T4, and its activated form T3. The production of these highly depends on the amount of available iodine.

position of the thyroid - comic
The thyroid is at the base of the neck

The roles of the thyroid

Thyroid hormones participate in various major functions:

  • regulation of the body temperature, especially by activating the brown fat2
  • metabolism of proteins, lipids and carbohydrates
  • brain function including neurons
  • reproductive system3
  • heart and muscle functions
  • filtering of the kidneys4
  • digestive system (liver)5
  • hair and nails growth
  • oxygen uptake by the cells6

The other roles of iodine

Apart from the functions provided by the thyroid and its hormones, iodine would provide many functions:

  • support of breast7, ovaries, uterus, prostate, and pituitary glands health
  • assistance in the regulation of blood pressure8 and blood glucose
  • antioxidant effect in certain tissues (especially the breast)9
  • prevention of endometrial cancers (internal lining of the uterus), breast and ovaries10 (hormone production)
  • prevention of thyroid, breast and stomach cancers11

I did also read about some other roles of the iodine but that I could not double check them:

  • disinfecting” action in the tissues facing fungal infections and skin problems (candidosis, mycosis, eczema, etc.)
  • assists in the removal of fluorine, bromine, lead, cadmium, arsenic, aluminum and mercury
  • protection against electromagnetism, radioactivity, various toxins and environmental pollutants
  • regulation of moods and supports good mental health (and therefore an ally against degenerative diseases?)

Symptoms of iodine deficiency

The symptoms of iodine deficiency are those of a hypothyroidism:

  • tired
  • memory problems
  • moody, emotional issues
  • constipated
  • lack of appetite
  • cramps
  • pain everywhere
  • weight gain
  • cold / chilly
  • dry skin
  • the heart slows down and the tension drops
  • nocturnal sweat
  • nausea

When extreme, it forms a goiter, which is very characteristic (thyroid that swells). But in the vast majority of cases, the deficiency is far from obvious.

In mice

laboratory mouse - comic

The trigger of iodine deficiency in mice shows some serious effects:

  • thyroid cancer12
  • DNA degradation in the thyroid13
  • decrease in the number of proteins14

Iodine and maternity

pregnant woman - comic

The hormone T4, composed of iodine, plays a critical role in the development of the central nervous system of the embryo.

The WHO has classified the United Kingdom as a country with moderate iodine deficiency since 2011. Consequently, UK decided to conduct a study15 on iodine-deficient mothers and the intelligence of their children (2015). The results are scary: if you show an iodine deficiency at the beginning of your pregnancy, your child has a 60% risk of being in the quarter his class with the lowest scores (expression, reading and comprehension). Iodine is therefore essential for the proper development of the child’s brain! The issue cannot be fixed afterwards (at least not completely).

surprised - comic

But… what are the reasons for this iodine deficiency?

The soil is poor in iodine. It is rinsed by the rains that evacuate the precious molecule to the streams. Few foods therefore contain iodine. But this explanation isn’t enough…

The halogen family

The halogen family includes:

  • chlorine
  • fluorine
  • bromine
  • and…. iodine!

These 4 elements have very similar properties. In the body, they compete for some cell receptors. They take the place of iodine, but don’t perform the same role. An excess of chlorine, fluorine or bromine will therefore tend to drive iodine away from the body.

You see where I’m going? These three products are found everywhere: drinking water (chlorine and fluorine), toothpaste (fluoride), household products (chlorine), bakery products (they contain bromine in the United States, but rarely in Europe), etc. So it isn’t the shortage in the soil that must be blamed, but once again the toxicity of our environment.

Before you even consider supplements, make sure to remove the sources of chlorine, fluorine and bromine as much as possible. For example, you can begin by using a toothpaste without fluoride. You can also leave tap water in open air for a few hours so that chlorine evaporates. Eliminating sources of endocrine disruptors and heavy metals is also necessary.

How do you know if you’re deficient?

Several tests exist, including hair mineral analysis, which is reliable for iodine16. That being said, it’s always possible to consume iodine, progressively increase the amount, and observe its benefits (if any). You don’t risk much. To be in excess of iodine, you really have to over do it! (like eating seaweed daily for example)

Sources of iodine

The limits of iodized salt

iodized salt crystals
iodized salt crystals

Iodized salt, although based on a good intention from the WHO, represents a very limited intake of iodine – not to say: really insufficient (some will even talk about a scam).

Here are the reasons:

  1. the amount of iodine is too low: the aim was to prevent goiter, but it isn’t enough to prevent a deficiency
  2. iodine evaporates very easily: the quantity displayed is measured directly after production. Between the factory and your plate, more than 50% of the iodine in the salt may have evaporated (especially since you don’t know how much time it was stored when you buy it)
  3. the bioavailability of iodine in the salt is very low (around 10%), especially since the salt contains a lot of chlorine ( NaCl ), in direct competition with iodine because they belong to the same family (halogens, for those who didn’t follow)

There is a lot of confusion around salt today. Indeed, ionized (NOT iodized) table salt has been much criticized recently (especially over hyper tension), and for a good reason: it’s completely processed, which makes it inefficient and even harmful. As a result, many people have turned (me also) toward quality salt: sea salt or pink Himalayan salt. These are very good products, but they don’t contain iodine.

In any case, it’ll probably not be salt that will fix our iodine deficiency.

Food sources

The soil is poor in iodine. Products from the soil are therefore low in iodine. However, there is no direct correlation between the amount of iodine available in the soil and that contained in food.

On the other hand, the farmers give iodine to their animals to protect them from infections  (the cows benefit from iodine supplements, but not us?!). The trace element is found in meats (3 to 9 mcg / 100g), but also in dairy products (where iodophors are sometimes also used as antiseptics). This contribution, however, remains very limited.

beef and chicken - comic

Seawater is rich in iodine (58 mcg / liter on average). To obtain a significant contribution, we must therefore turn toward sea products, like fish and seafood. But there is even better: seaweed17, unequaled champion in iodine level.


The sources of iodine are therefore very few:

  1. Seaweed
    1. kombu
    2. wakame
  2. Fish and seafood (watch out for heavy metals)
  3. Meat, dairy products and eggs (too limited)
  4. Iodized salt (too limited)

Seaweeds are very good foods that contain many minerals and vitamins. But depending on their environment, they may also contain pollutants or heavy metals. Yes, it’s always complicated…

Some numbers

Please note that these are average amounts, which can vary greatly from one product to another.

The human body contains in total 20 to 30 g of iodine. But it isn’t able to store it for a very long time. The recommended daily intake by the WHO is 150 mcg (micrograms), and 200 mcg for pregnant women. Some rural Japanese consume up to 13 to 43 mg per day!! That is 28 times the recommended daily intake. So you do have some margin before getting too much.

  • Seaweed18
    • Kombu 135 000 mcg / 100g
    • Wakame 4 000 mcg / 100g
  • Iodized salt: 20 mcg / g (or 1 mcg if we consider 50% evaporation and 10% bioavailability…)
  • Fish: 8 to 200 mcg / 100g (cod 1 17 mcg / 100g)
  • Seafood: 92 mcg / 100g
  • Shrimps: 41 mcg / 100g
  • Cheddar: 42 mcg / 100g
  • Egg19: 24 mcg / egg
  • Milk: 23 mcg / 100g
  • Yogurt: 31 mcg / 100g
  • Potato: 35 mcg / 100g
  • Beans in grain: 34 mcg / 100g
  • Meat:3 à 9 mcg / 100g (insignificant)

the list is long - parchment - comic


The daily recommendation is 150 to 200 mcg. So you can start with this quantity, and then gradually double (every two weeks). This gives the body some time to  adapt to a greater intake of iodine, and ensures that it’ll be well tolerated. It isn’t necessary to exceed 4 mg.

You can take a supplement of pure iodine, or in the form of seaweed (often named “kelp”).

If iodine intake is sufficient and the consumption of bromine and fluoride is avoided, the latters should be expelled from the body.

Associated supplements


In general, a mineral imbalance disrupts many vital mechanisms. Iodine and thyroid are no exception. Fix as much as possible your minerals inbalances.


Selenium also plays an important role in the  thyroid (synthesis of T3 and T4 hormones). Supplementing with iodine when one is deficient in selenium could worsen the situation (and vice versa). On the contrary, a intake of selenium supports the absorption of iodine.


During the mineral analysis of my hair and that of my girlfriend, our levels of iodine were sufficient, but low.

iodine - mineral hair analysis
Amount of iodine in my girlfriend’s hair.

Once again, we are not facing a deficiency caused by a shortage in food: it’s the pollutants (fluorine, chlorine and bromine) that disrupt our system by taking the place of iodine, leaving us in a situation of deficiency. I don’t use toothpaste anymore (it’s been 6 months), and my teeth are still as beautiful and clean as before – it’s the brushing that matters.

Given the major roles played by this trace element within the body, we (especially me) have decided to eat seaweed once a week (a portion, for example 100g of kombu for 2, probably spread over several meals), to support our thyroid system. We’ll see!

If you are tired too, I invite you to consider the iodine track, ignored by too many people.

And you? Do you get enough iodine? Leave me a note in the comments.

  1. WHO: Iodization of salt for the prevention and control of iodine deficiency disorders
  2. Thyroid Hormone Activates Brown Adipose Tissue and Increases Non-Shivering Thermogenesis – A Cohort Study in a Group of Thyroid Carcinoma Patients
  3. Damaged Reproduction: The Most Important Consequence of Iodine Deficiency
  4. Interactions between thyroid disorders and kidney disease
  5. Consequences of dysthyroidism on the digestive tract and viscera
  6. Thyroid hormone induced oxygen consumption and glucose uptake in human mononuclear cells.
  7. Iodine: deficiency and therapeutic considerations.
  8. Iodine status and its correlations with age, blood pressure, and thyroid volume in South Indian women above 35 years of age (Amrita Thyroid Survey)
  9. Iodine: deficiency and therapeutic considerations.
  10. Dietary iodine and breast risk, endometrial, and ovarian cancer.
  11. Role of iodine in carcinogenesis of thyroid, breast and stomach.
  12. Iodine deficiency thyroid cancer in rats and mice
  13. Iodine deficiency activates antioxidant genes and causes DNA damage in the thyroid gland of rats and mice decrease in brain weight
  14. Effects of high-dose iodine on brain development in mice
  15. The new emergence of iodine deficiency in the UK: consequences for child neurodevelopment
  16. Hair Iodine for Human Iodine Status Assessment
  17. Low-level seaweed supplementation improves iodine status in iodine-insufficient women
  18. How much Iodine is in Seaweed?
  19. Which foods contain a high level of iodine?
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2 thoughts on “Iodine deficiency: what happened? And why is it serious?”

  1. Make sure you don’t have heavy metals in your thyroid when you take iodine, it could cause Hashimoto.

    I have the theory that Hypothyroidism is caused by heavy metals in the thyroid, because the body wants to slow metabolism as it thinks it is in a contaminated food environment and waits to be in clean environment again.

    Because we’re always in a contaminated environment now this mechanism doesn’t work anymore, so if you take iodine you increase the metabolism and the body begins to attack the thyroid to get rid of the heavy metals.

    There is also Myasthenia Gravis where the body attacks the thymus gland, it’s probably the same mechanism.

    Regarding bromine you shouldn’t have to worry when in Europe, only in USA and Great Britain you should worry.

    In the USA it’s added to dough to make it more fluffy (except for California where it has to be labeled) and in Great Britain it is in every furniture as a flame retardant (that’s probably why there a so many obese people as bromine is an endocrine disruptor).

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