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GovXContentSection Iodine is a natural chemical element, just like oxygen, hydrogen and iron, which is naturally found in certain food products, supplemented to others, and is also available as a dietary supplement. Iodine is nutritious and critical for proper health, in all stages of life. It is critical for the proper function of the thyroid gland, especially before and during pregnancy and breastfeeding for the proper brain development of fetuses and newborn.
When iodine reaches the bloodstream, the thyroid gland absorbs it in the amounts that it needs in order to synthesize the thyroid hormones, which are then secreted into the bloodstream and are transported to different areas in the body. Every cell, tissue or organ requires the thyroid hormones, which help the body to utilize energy, maintain heat and normal activity of the brain, the heart, the muscles and other organs.
Iodine in nutrition
The content of iodine in food and in nutrition in general depends on the cultural conditions (the way in which the food is consumed) in addition to geographical conditions - chemical and ground conditions.
The main sources of iodine in food, with varying degrees between the different food sources:
- Seaweeds
- Fish (and seafood)
- Dairy products, especially in liquid form
- Eggs
- Fish
Enriched food sources: iodized salt (usually 30 micrograms of iodine per one gram of salt) and industrial foods to which iodine or iodized salt has been added (usually not found in Israel).
Dietary supplements: can be purchased with or without a prescription in different dosages (75-220 micrograms per tablet).
Recommended daily amount of iodine
| Children (1-8 years) |
90 |
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| Children (9-16 years) |
120 |
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| Adults |
150 |
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| Pregnant women |
220 |
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| Nursing women |
290 |
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* According to the Israeli and the American nutrition ration
The danger in not consuming enough iodine
An iodine deficiency is the most common of the preventable causes of deficient cognitive development. Disorders of iodine deficiency can also cause hypothyroidism, goiter and stunted growth, both physical and mental, resulting from a severe iodine deficiency during pregnancy (cretinism). Even a slight deficiency during pregnancy, infancy and childhood can cause irreversible damage to the developing brain and nervous system and can diminish the mental capacity of school age children and at later stages.
The state in Israel
For many years the common assumption was that due to the proximity to the Mediterranean Sea the consumption of iodine was sufficient and that iodine deficiency should not develop amongst Israelis. However, a countrywide survey that was recently carried out discovered a high frequency of iodine deficiency in children and pregnant women. It is possible that most Israelis, adults and children alike, do not consume enough iodine.
In Israel, as opposed to the vast majority of other countries in the world, the problem of iodine deficiency is significant. This is due to the fact that up until now there have been no legislation or regulations that require salt to be enriched with iodine, as is done in other countries. Therefore, only very low percentages of the salts that are marketed in Israel have been enriched with iodine (in other countries: 80%-90%)
The following populations are at an increased risk for iodine deficiency:
- People who do not eat fish or dairy products (for example, due to an allergy or intolerance), vegetarians and vegans. However, a study that was conducted in Israel showed that there is also reason to suspect iodine deficiency amongst the general population.
- For women of childbearing age, especially those planning a pregnancy, it is recommended to ensure that they consume the amount of iodine recommended for adults, in order to fill the iodine reservoirs in their thyroid gland and to assist in their proper function during pregnancy.
- Pregnant women need to consume a greater amount of iodine in order to allow them to provide for their own hormonal needs as well as those of the fetus during pregnancy.
- Nursing mothers need to consume a suitable amount of iodine, in order to provide iodine to their newborn child, whose brain is still developing.
In order to check if you are in a high risk group, please consult with a dietician.
The efficient way to prevent iodine deficiency
The best way to prevent iodine deficiency is by switching regular salt with iodized salt, without adding to the amount of consumed salt. In many countries in the world it was found that the addition of iodine to table salt greatly reduced the iodine deficiency among the public.
Consumption of dietary supplements
A healthy, balanced diet that includes dairy products as well as fish usually provides the amount of iodine that is recommended for the majority of the adult population. The consumption of an iodine supplement is helpful only for those who do not usually consume food that is rich enough in iodine for his or her bodily needs. For patients with thyroid related diseases, those who take medications, or those who experienced an iodine deficiency for many years, it is recommended to seek the advice of a dietician or physician before taking an iodine supplement. The supplement needs to contain “potassium-iodide” up to 150 micrograms (for adults). Healthy pregnant women and nursing mothers who are unsure if they consume enough iodine should consult with a dietitian.
This information is provided in collaboration with Maccabi Healthcare Services and the Hebrew University
Questions and answers regarding iodine
- How does one know if a person consumes enough iodine?
Recently, it was discovered that in order to measure the amount of iodine in a person, the concentrations of iodine must be measured in the urine for at least 10 days straight. This means that currently there is no efficient means of measuring the consumption of iodine of a single person, and the measurements are done only in groups in order to screen the interpersonal differences and the day to day differences in iodine intake.
- What are the symptoms of iodine deficiency?
There are a number of popular advertisements that provide a list of symptoms for iodine deficiency. In most cases, iodine deficiency lacks symptoms, and under certain conditions iodine appears alongside symptoms of hypothyroidism: weakness, fatigue, dry skin, unexplained weight gain, sensitivity to cold, and more.
A severe and continuing lack of iodine in one's diet causes interference in the production of the thyroid hormones. Since the thyroid gland has good compensation mechanisms, with the current levels of iodine deficiency in the country (small to medium levels) hypothyroidism is very rare.
In the past, goiter (abnormal enlargement of the thyroid gland which is caused so that the body can absorb more iodine, and thus ensure the proper formation of the hormones) was thought to be the most common expression of iodine deficiency. Goiter is not always visible and sometimes when it finally is visible the situation is irreversible. However, the frequency of goiter is not common and iodine deficiency is more common than goiter.
- Why is iodine deficiency so dangerous?
A slight deficiency in iodine can bring about a subclinical (asymptomatic) disorder of the thyroid gland function and can minimize the formation of its hormones. Sometimes, these disorders occur during pregnancy and breastfeeding, when the woman's body needs a greater amount of iodine due to the need to share nutrients with the developing fetus and the nursing newborn. This is the sensitive stage during which issues can arise. Even a relatively slight decrease in the thyroid hormone levels can limit the development of the brain of the fetus.
A more serious iodine deficiency can increase the possibility of growth and developmental disorders in the child, and at a certain point even severe mental retardation, called “cretinism”. In cases of severe iodine deficiency, there is a high risk of deficient mental and intellectual development, which is expressed in a loss of around 10 IQ points in children. It can be assumed that in such cases, those children will experience difficulties at school, especially in mathematics and grammar, in which abstract thinking is very important.The commonly accepted thought and directives of the American Thyroid
Association, European Thyroid Association, the WHO, and the IGN (Iodine Global Network) is that addition of iodine to the diet, even in areas in which deficiencies are slight to moderate, is important for optimal mental development, but up until now the research has not been definitive.
- Can I consume too much iodine?
Yes. Excessive iodine consumption can harm the thyroid gland, and therefore must be avoided.
The upper limit for maximum iodine consumption:
| Children (1-8 years) |
200 |
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| Children (9-16 years) |
300 |
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| Adults |
600 |
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| Pregnant women |
900 |
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| Nursing women |
1,100 |
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- However, excess iodine in the diet is rare in Israel. In the few studies that have been carried out with Israelis, it was discovered that the highest amount of iodine that a single Israeli person consumed was 300 micrograms per day (only half of the most conservative upper limit that is recommended for consumption per day - 600 micrograms per day). Chronically consuming excessive iodine can cause health problems, such as hyperthyroidism, and even autoimmune diseases of the thyroid gland. In areas in which there is a shortage of iodine, as was recently discovered in Israel, we can see these thyroid gland disorders even after excessive iodine consumption for a very short period of time of only several days.
- How is it determined that people living in a country or a certain area suffer from iodine deficiency in their diet?
This information is determined through surveys (estimations) which are performed by researchers in the field. The commonly accepted method of evaluating iodine deficiency is by determining in a lab the concentration of iodine in urine, due to the fact that 90% of the iodine in a person’s diet is excreted through the kidneys in the urine.
In order to evaluate if there is an iodine deficiency, the median amount of iodine in the urine is used, which is calculated on the basis of lab results that are received form hundreds or thousands of people. Based on a large scale survey that was conducted in Israel in 2016, there is an iodine deficiency in all of the areas of the country.
The survey was performed among both school age children and pregnant women (based on the recommendation of the World Health Organization). These results show that there is a need for preventative treatment for iodine deficiency at the level of the population.
- What foods are naturally rich with iodine? Is it possible to consume these products in order to normalize my iodine consumption?
Iodine is found in relatively high concentrations (sometimes too high) in certain seaweeds, mostly those that grow in sea water. A relatively high amount of iodine exists in seafood (shrimp, shellfish and more), as well as in sea fish, yet the iodine content in these sources varies greatly (depending on the source or method of artificial growth).
In addition, in order to ensure the sufficient daily intake of iodine from these sources, a very large amount of fish or seafood must be consumed daily (more than half a kilo).
Increasing iodine consumption through seafood and sea fish in large amounts is unsuitable for most Israeli society due to dietary preferences, kosher customs, and the relatively high cost. Among most countries in the world, only the Japanese and the South Koreans can pride themselves in a high consumption of iodine from a local diet, which includes a large amount of seaweed.
- I was told that I have an iodine allergy. Can I eat food with iodine?
Sometimes iodine is used in medical tests, when it is injected as a contrasting agent in order to color organs and to improve the ability to analyze the test results. Based on tests and studies, the iodine itself does not cause allergies. The side effects and symptoms that have been linked to iodine seems to have to do with the viscosity of the contrasting agent, mostly when they are directly injected into a person.
- Is sea salt naturally rich in iodine?
No. While the sea water from which we get the salt by evaporation does contain iodine, only negligible amounts remain in the final product. This is due to the fact that in the process of evaporation, washing and drying, most of the iodine is lost. One gram of sea salt contains only one microgram of iodine, while iodine enriched salt in Israel usually contains 30 micrograms per gram of salt. However, sea salt can also be enriched with iodine, so it will combine the properties of the sea salt and the benefits of iodized salt.
- Is there a reliable alternative to iodine enriched salt?
Iodine enriched salt has a history of about 100 years. The production and use of regular salt containing iodine started in the early 1920s in Switzerland and the United States. In the past decades, dozens of countries started to actively apply programs making it obligatory to enrich salt, including countries with large populations such as China, India and Indonesia.
- So it is in fact recommended to consume iodine enriched salt?
The best way to prevent iodine deficiency is to switch regular salt with iodized salt, without increasing the amount of salt that is consumed. Health establishments recommend consuming low sodium salt, and at the most up to one teaspoon of salt a day. Most iodized salt that is marketed in Israel contains 30 micrograms of iodine per single microgram of salt, so that one teaspoon of salt (about 50 grams) is enough to provide an adult’s daily requirement, which is 150 micrograms per day (this does not include pregnant or nursing women, for whom it is recommended to consume 220 and 290 micrograms a day, respectively).
- I hear that salt containing iodine is unstable in heat (when cooked) and that it has a short shelf life (3-4 months).
According to the most recent industry standards, potassium iodate (KIO3) is the compound that is used in the production of iodized salt. Salt that is enriched with potassium iodate is stable in a hot and humid environment. During the preparation of hot meals, there can be a loss of 20%-50% of the iodine. The amount of iodine that remains should be enough for the needs of the body, because when the iodine is added in the production of the salt, they calculate the amount added to the salt to make up for what is lost during the cooking process.
The shelf life of iodized salt is around one year, although there are certain types of salt for whom the shelf life is even longer.
- Is exposure to desalinated seawater a cause of iodine deficiency or thyroid gland morbidity?
Not necessarily. It is true that desalinated water contain negligible amounts of iodine, if any at all. It is entirely possible that in a situation in which the population is chronically exposed only to desalinated water, in an area where it is not customary to use salt, there is the danger of iodine deficiency. However, between this to morbidity there is a great distance. Often, in order to reach a deficiency, even more so to a chronic deficiency that causes morbidity, there must be a few different accumulative factors, including the policies of the health authorities, dietary preferences, genetic factors, as well as ethnicity and gender.
- How does enriching salt with iodine jibe with the Ministry of Health’s policy to decrease salt consumption?
As the salt consumption goes down, the amount of iodine in salt will be adjusted accordingly.
- What does the Ministry of Health intends to do?
The Ministry of Health intends to enrich table salt and also enriching industrial salt is possible as well.
- How will we know if the enrichment of salt is working?
The Ministry of Health is planning another iodine survey in a few years in order to evaluate the effect of salt enrichment on the iodine levels in the population.
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