Iodine: How do you recognize a deficiency and what is it good for?

Iodine is a popular dietary supplement in the Netherlands. It's also sometimes added to salt (and bread). In this article, we'll explain all the benefits of iodine, how to recognize a deficiency, and how to get it through food.

Iodine is an essential trace element. It's important for your health, especially for the production of thyroid hormones. Because your body can't produce iodine itself, you must get it from food (fish, iodized salt, and seaweed) or supplements.

The production of thyroid hormones is the primary function of iodine. All other iodine functions in the body are related to and dependent on the action of these hormones.

Because iodine is so important for thyroid function, it also plays an indirect role in:

• Energy level - Iodine helps release energy from food
• Nervous system and cognitive functions - Iodine plays an important role in the functioning of nerves and is good for memory and concentration
• Growth and development - Iodine is important for the normal growth of children
• Skin health - Iodine helps keep the skin healthy

Various forms of iodine are found in food, primarily as iodide and iodate. Our bodies can absorb and utilize these forms of iodine.

Iodide (I-)

• This is the most common form of iodine in food and supplements
• Occurs in seawater and is therefore present in seaweed, seafood and iodized salt

Iodate (IO3-)

• This form is often used to iodate salt
• Found in iodized table salt and baker's salt

There is a third form of iodine, diiodine (I2) . Although diiodine is the pure, elemental form of iodine, it does not occur naturally in foods. It is primarily used in laboratories and as a disinfectant.

It is recommended for adults to eat 150 mcg of iodine daily.

Because iodine is important for the growth of children, pregnant women and children have a special need:

Although most Dutch people get enough iodine (through diet), many people worldwide are at risk of deficiency. This is especially true in regions where the soil naturally contains little iodine.

International initiatives such as salt iodization have contributed significantly to reducing deficiencies. Yet, one-third of the world's population is still iodine deficient(2)

Unfortunately, you often don't discover you have an iodine deficiency until very late. This is because your body can store iodine in the thyroid gland. This means you have a "reserve" supply for quite a while.

A deficiency begins with an underactive thyroid (goiter). This can be recognized by the following symptoms:

• Weight gain
• Getting cold faster
• Blockage Slowness

When children have an iodine deficiency, you can notice this by:

• Growth retardation (1)
• Less able to learn (1)

* An iodine supplement is not intended to cure any disease or condition.

People at increased risk for iodine deficiency include:

• Vegetarians and vegans – these groups often do not eat products such as fish and eggs, which are rich in iodine.
• Pregnant and breastfeeding women - due to the increased need for the baby's development and the loss of iodine through breast milk.(2)
• People who bake their own bread without using baker's salt - Organic bread and home-made bread often contain little to no added iodine.
• People who consume little or no bread - bread, especially iodized baker's salt, is an important source of iodine in the Netherlands.

If you are at risk for iodine deficiency, these actions may help you supplement your iodine intake:

1. Eat fish and sea vegetables - Fish (from the sea!) and sea vegetables like seaweed are natural sources of iodine. These natural sources are absorbed very well by the body. More than 90%! (3). Iodine added to iodized salt, on the other hand, is less well absorbed.
2. Use iodized salt - Choose iodized table salt or kitchen salt when preparing meals. This is an easy way to add iodine to your diet.
3. Use iodized bread products - If you eat bread, choose bread baked with iodized salt (baker's salt). Check the label or ask your baker.
4. Consider iodine supplements - If you have trouble getting enough iodine from food, an iodine supplement may help. Consult a healthcare professional first.
5. Eat fewer cruciferous vegetables - These are vegetables such as broccoli, cabbage and cauliflower, which contain a substance that can hinder the absorption of iodine by the thyroid gland.
6. Be aware of plant-based milk alternatives - Beverages such as soy can affect iodine absorption and often contain less iodine than cow's milk. (2)

Oceans contain most of the world's iodine supply. Therefore, good sources of iodine are foods that come from the sea.

But evaporation from ocean water also releases some iodine into the soil. As a result, crops grown near the coast have a higher iodine content than those grown inland.(3)

Here are some examples of iodine-rich foods:

With a healthy thyroid, you don't have to worry much about too much iodine. However, with an underactive thyroid, excessive iodine intake can lead to an enlarged thyroid gland.

The European Food Safety Authority (EFSA) has determined that up to 600 micrograms of iodine is safe for adults (18 years and over).(1)

Symptoms of too much iodine may include:

• Diarrhea
• Weight loss (in combination with a good appetite)
• Palpitations
• Nervousness

Just like an iodine deficiency, you will also not easily get too much iodine.

But be careful with:

• Excessive use of iodized salt
• Eating too much of foods naturally high in iodine, such as seaweed
• Overconsumption of supplements containing iodine

If you know (for sure) that your iodine level is too high, you can reduce it in the following ways:

1. Stop or reduce your intake of iodized salt, seaweed, or supplements.
2. Eat more c ruciferous vegetables, such as Broccoli, cabbage, and cauliflower. This temporarily reduces iodine absorption.
3. Drink/Eat more soy products.

Earlier in this article I explained how iodine is essential for thyroid function.

The thyroid gland requires iodine from food to produce thyroid hormones such as thyroxine (T4) and triiodothyronine (T3). These hormones contribute to a healthy metabolism, growth, and development. They also play a role in regulating your body temperature.

If you don't eat enough iodine, your thyroid can either become underactive (hypothyroidism) or enlarge (goiter). Therefore, an adequate iodine intake in your diet is important for healthy thyroid function.

Whether it's best to buy salt with or without added iodine depends on your individual iodine needs. If you generally get enough iodine through your diet, salt without added iodine will suffice.

However, if you are at risk for iodine deficiency (for example, if you eat little fish), iodized salt can help increase your iodine intake and prevent deficiencies.

Consider your personal situation and consult a healthcare professional for advice if necessary.

Want to know how I do it? This is how I ensure I get enough iodine:

1. First of all, I eat a varied diet, with fish and/or seaweed (sushi!) once or twice a week. This way, I get enough iodine.
2. It's usually not necessary to use iodine tablets as a supplement to my normal diet. This may only be necessary for vegans/vegetarians or if you have a very limited diet.
3. When I consider buying an iodine supplement, I choose one that contains a safe dose of iodine, for example from potassium iodide, such as in Multi Premium.

Sources used

(1) Nutrition Center. (n.d.). Iodine . https://www.voedingscentrum.nl/encyclopedie/jodium

(2) Hatch-McChesney, A., & Lieberman, H. R. (2022). Iodine and Iodine Deficiency: A Comprehensive Review of a Re-Emerging Issue. Nutrients , 14 (17), 3474. https://doi.org/10.3390/nu14173474

(3) Ahad, F., & Ganie, S.A. (2010, March 1). Iodine, Iodine metabolism and Iodine deficiency disorders revisited . PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3063534/