Iodine deserves a separate article. I’ve written about it in several other places, but the topic is important enough that it should be in the main blog.

I’ll start by ranting a bit. People interested in the alternative can be divided into two large groups.

The first is the fanatical supporters. They believe everything they read on the internet. If something hasn’t been researched – it definitely works, because that’s why the evil corporations haven’t researched it.

The second, equally stupid – fanatical opponents. They believe that everything on the internet that isn’t on wikipedia isn’t true. If something hasn’t been tested – it certainly doesn’t work, because if it did, surely the good pharmaceutical companies would have tested it.

I think both of these cases are mostly about pumping up your ego. Both sides of the barricade think they are fighting for something good, both feel they are part of some larger community. It’s a bit like with football fans or racists, by joining a trend, identifying with a group you can feel superior to others.

In the case of iodine I remember discussions with representatives of both currents of concrete. A fanatic advocate of drinking doses several hundred times higher than the recommended intake believed that absolutely nothing bad could happen, and when he saw a study where every second person had side effects – he said that probably later these people would get better.

In turn, the doctor, who decided to “talk sense” to the representative of the evil, stupid trend of the alternative (that is me), explained that the deficiency certainly does not exist, because it does not, after all, if there were he would know about it. When I showed him studies that show that there are deficiencies and that they are massive – some contacts in his head got burned, he started to call me names and blocked me.

This translates into the availability of information – a person looking for something about this element ends up either on sites run by fanatical supporters, or on sites of opponents. It is difficult for someone not familiar with medicine or methodology to find his way around. Hence the need for this entry – an attempt to take a rational look at the issue, taking into account both the advantages and disadvantages of supplementation.


There is not much room for error here – supplements are divided into organic (e.g. kelp) and inorganic (usually potassium iodide). I sincerely advise against all organic forms, apart from the problem of how they are absorbed (according to some researchers they are much worse and cause more problems, according to others they are better), but the main problem is contamination. Preparations like kelp necessarily have to have other elements from the same group in them – mainly fluorine and bromine. They have a clear negative effect on the thyroid. Sometimes they are also contaminated with heavy metals. And above all – they are damn expensive.

The right supplement is potassium iodide. But it’s not available in every country.

What’s left?

Either you have to smile at a multivitamin, or you have to import pills from, say, Iherb or Vitacost, or… make the supplement yourself. The latter is quite troublesome, a mistake of 3 zeros in school is an F in chemistry, in real life – severe poisoning. However, if you want to become a chemist, you can buy potassium iodide or even regular iodine, dissolve it in water and then measure the proper dose with a syringe.

We make healthy supplements!

For the brave, I give the values:

0.8 grams of potassium iodide is 800 mg, of which iodine alone will be 620 mg (calculated from molar masses).

0.8 grams of potassium iodide dissolved in 200 ml of water will give about 3 mg of iodine / 1 ml of solution

0.8 grams dissolved in 2 liters of water will give 0.3 mg (300 mcg) in 1 ml.

0.4 grams dissolved in 2 liters will give exactly 150 mcg/ml, which is the amount you should take daily.

Iodine tincture and Lugol’s solution are less reliable sources – the atomic iodine contained in them can evaporate, secondly, they are highly reactive.


This is true for most European countries and for large parts of USA. Since salt iodization was introduced, which means – literally – that supplementation was forced on each of us, the health of the Polish society has improved significantly. Fewer stupid children are born, generally healthier children are born, presumably it even had an impact on life expectancy.

As salt iodization has been introduced systematically over many years, only the most recent studies will be relevant. Any study where patients fill out questionnaires about what they ate should be thrown in the trash – the right indicator is the amount of iodine found in urine. According to WHO recommendations, there should be between 100 and 200 mcg/l there, with values below 50 mcg/l being already a severe deficiency. For pregnant women, the ideal result is 200 mcg/l and the minimum value is 150 mcg/l:

Let’s take a look at the studies conducted in my country:

Here the results of children before and after the introduction of compulsory salt iodization were compared. It went up very nicely, but still the average result was only 93 mcg/l, more than half of the kids had a result below the recommended value. But you have to take into account that the same kid can have a result above the recommended value on the next day, because he just happens to eat cod for dinner. Nevertheless, the “ideal” level of 150 mcg/l is far from being reached, so some kids will have deficiency problems.

Let’s take a look at the study of pregnant women – it’s interesting, because they are recommended to take iodine supplements as low levels are very bad for the baby’s health:

The average level was 112 mcg/l, with an average of only 97 mcg/l for the group that did not take supplements.

This means that the average pregnant woman not taking supplements has only half the “ideal” iodine levels, which seriously affects the health of children, for example, mothers with low levels of thyroid hormones have been found to be four times more likely to give birth to children with autism (but they will still tell themselves that vaccines are to blame):

We have another study on the condition of children:

This time it’s slightly better – the average concentration is 101 mcg/l. But it’s still 50 mcg/l less than it should be to ensure ideal levels in most children. I remind you that this is an average intake – if it is 101 mcg/l, there will be kids in the group who have just 50 as well as those who will have 150. So you aim for higher values, but not such that some people fall over 250 mcg/l.

To sum up – to fit into the official WHO standards, a statistical person in Poland should have 50 mcg/l more iodine in his urine. This does not mean that he should consume 50 mcg of iodine – to achieve such an effect, he should consume about 150 mcg a day additionally. A pregnant woman should take supplements containing up to 250 mcg of iodine (by the way, these are probably the ones most often recommended by doctors). The ideal situation is to break this down into two doses per day.


In a word of introduction – iodine is responsible for the state of the thyroid gland. It can be said that the only function of this organ is to convert iodine into hormones. If there is too little of this element, we will fall into hypothyroidism – and here there is no way for it to be otherwise. Of course, not every hypothyroidism is the result of a deficiency, but a deficiency will always end in this disease. And here we have the first problem – endocrinologists.

We have situations where the decisions of endocrinologists are simply bizarre. I encountered a case of a woman who had been to five (!) different doctors, from each of whom she received a completely different diagnosis and, consequently, five different recommended treatments. Logically, at least four of those doctors were wrong. Quite recently, on a forum, a woman went to a “specialist” with her hypothyroidism – she had thyroid results indicating a problem, plus a whole set of accompanying symptoms – elevated prolactin, blood pressure too low, problems with constipation, and so on. What did the esteemed doctor say? “Your thyroid is fine, you don’t read crap on the internet, here’s a prescription for prolactin medication, here for low blood pressure, here for bowel problems…”. As a result, she wrote her prescriptions for over $400 PLN per month. For comparison, thyroid treatment, which would eliminate all these problems, is about $10 a month in my country.

I myself once had an unpleasant situation, when I went to a doctor to ask if she could give me iodine supplements – as a vegetarian I suspected deficiency, I was afraid that my thyroid would not work as it should. She said no way, she could order me a thyroid test, and if it came out that I had a problem – she would write me a prescription for hormones. Moron.

These are obvious mistakes, but we also have a not so clear, much more common one – treating iodine deficiency with hormones. As I wrote, low levels of this element always lead to hypothyroidism. The proper solution is to supplement the deficiency, so that the poor thyroid would have the raw material to produce hormones – instead of that doctors prescribe synthetics, which may eliminate the symptoms, but once they can become addictive (an unused organ atrophies, if we replace the thyroid in its work long enough). If someone has a deficiency of vitamin B12 and anemia associated with it, he is given the vitamin in tablets or injections, and not blood transfussion every month.

The question arises – what about hyperactivity? Since a low level of iodine leads to a weak work of the thyroid gland, won’t a high level of iodine lead to its overactivity? Here the answer is surprising – it is the low level that can lead to hyperthyroidism. The mechanism is very simple – compensation occurs when there is too little of this element, the thyroid gland is simply stimulated much more strongly. Although there are no clinical symptoms of hypothyroidism, forcing the organ to work too intensively does not end well for it. To make things worse – a significantly increased intake of iodine also sometimes leads to hyperthyroidism, but not as a result of a simple increase in production, but because of disturbances in the work of the organ, which eventually lead to its degeneration.

Statistical studies show that the optimal level of iodine intake is close to the recommended one – then the frequency of diseases of this organ is the lowest:

The overall risk of thyroid cancer remains similar with both too high and too low intake, but higher levels make the less dangerous variety more likely to appear.

That leaves one condition – autoimmune thyroiditis, Hashimoto’s disease. Here research leaves no doubt – higher iodine intake is associated with increased incidence. We have an example from Poland, where the amount of disease increased as much as four times (to almost 6%) after the introduction of iodized salt:

This type of study has one major drawback – it is not known whether these individuals simply did not already have an asymptomatic disease that would have occurred at a later time anyway; it is known that iodine can accelerate such a process. Nevertheless, a fourfold higher incidence of disease is too high a result to be entirely “justified” by such a mechanism. Since practically all studies conducted so far have given similar results, it is safe to assume that iodine supplementation above the recommended dose increases the risk of Hashimoto’s disease up to several times.

Admittedly, there are claims that the increased risk applies mainly to those people who previously had a deficiency of this element, but the conclusions for the average reader remain the same – if you have an iodine deficiency and start supplementing it, you risk an autoimmune disease.

Is Hashimoto’s dangerous? Not really. At worst, you’ll end up having to ingest synthetic hormone pills (which would be a necessity anyway if you have a prolonged iodine deficiency). The disease does not have any serious consequences if you take these pills. You can minimize the risk if you take selenium in parallel with iodine.

It is possible to come across revelations that very high doses of iodine (hundreds of times more than recommended) will cure autoimmune thyroiditis. They come entirely from one “doctor” who justified the high doses on the grounds that… we consumed so much iodine before God banished us from Paradise, therefore such consumption is natural. Well, there are people who will believe literally anyone who says what they want to hear.

To sum up – additional supplementation will protect a lot of people from hypothyroidism and the need to take synthetic supplements, but in some people it will also lead to autoimmune disease, which will force them to take these pills. The rate of hyperthyroidism will remain almost unchanged, the overall rate of thyroid cancer will also remain unchanged, but the incidence of the more serious variety will decrease, which will reduce mortality.


Finally, the most interesting aspect – cancer. Iodine is essential for proper thyroid function, it is true. But not only. Cells that have the ability to accumulate it are also found in the prostate and breast glands. It has long been rumored that iodine intake can significantly reduce the incidence of these diseases – recall that statistically, one in thirty people die from breast or prostate cancer (overall, cancer kills one in four of us).

Most studies concern breast cancer, unfortunately no one has conducted them on a larger scale – anyway, who would sponsor such a study?

Here a cancer-causing substance was given to two groups of rats – one had a normal diet, the other received relatively high doses of iodine. Seventy-two percent of the normally fed rats developed cancerous lesions, but only 30% of those that received iodine, with only the atomic form of iodine (such as is found in iodine tincture, for example, but not potassium iodide) having an effect.

There are quite a few studies where herbs rich in iodine stopped the development of breast cancer in rats, or literally killed human cancer cells, leaving healthy cells intact:

Studies clearly show that women with breast cancer are much more likely to have concurrent thyroid disease, indicating deficiency:

Comparing breast and prostate cancer mortality rates in Japan and the US shows a several-fold difference, with Japan consuming several times more iodine (but not as much as various alt-blogs suggest). What’s more interesting is that Japanese who go to America and accept the diet there have mortality rates identical to a typical resident there, so it has nothing to do with genes.

We have similar results for prostate cancer – people with thyroid disorders have a 3-4 times higher risk of getting the disease:

In this study, the iodine intake was found to have little effect, but you have to take into account that what was really studied was how much iodine the patients consumed the day before the study, not how much over the course of, say, a year.

Looking at the disease statistics in Poland, it is clear that the introduction of iodized salt did not significantly reduce the risk – perhaps even did not affect it at all. This means that either iodine has little effect, or that the dose was simply too low to make any difference.

It has also been suggested that iodine deficiency may significantly affect the risk of endometrial cancer and ovarian cancer.

Presumably iodine has little effect on the other cancers, as can be seen by comparing the incidence in Japan and in countries with low intake.

It seems that this is the solution to the mystery of low breast cancer incidence

It is also worth noting here that breast cancer incidence statistics are lower in India than in Japan – where Japan is the country with perhaps the highest iodine intake in the world, India has one of the lowest. What these countries have in common is diet – the vast majority of calories come from carbohydrates, meat and saturated fat intake is very low.

In summary, low iodine levels appear to be a significant risk factor for several cancers, supplementation can reduce risk by up to several tens of percent, but compared to, for example, a general diet that can reduce risk by several hundred percent – its impact is marginal. Nevertheless, even if iodine were to reduce these risks by one-third, its supplementation would save the life of one in a hundred people.