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We need iodine to make thyroid hormone, which we use to regulate energy in our body. Our babies also need thyroid hormone for the proper development of their skeletal and central nervous system before and after birth. This means it is extremely important to get proper iodine levels during pregnancy and lactation.

The only good and reliable whole-foods, plant-based source is seaweed, but levels vary tremendously. Kelp, for example, has about 3855 mcg of iodine in just half a tablespoon! Meanwhile, one sheet of nori (like the ones used to make sushi) only offers between 35 and 55 mcg.

When it comes to iodine, excess is just as bad for us as deficiency. If we get too little, we could develop hypothyroidism. This is when our thyroid doesn’t make enough thyroid hormone, resulting in a slower metabolism, trouble regulating our body temperature, and fatigue.

Ingesting too much iodine can lead to hyperthyroidism, which is the production of excessive thyroid hormone that increases our metabolism, gives us a fast and irregular heartbeat, and causes irritability, among other symptoms.

Try our personalized calculator below to determine how much iodine you need and what your maximum intake should be. Also, learn about different sources of iodine, and discover some interesting facts about iodine and our health.

Top Whole-Food, Plant-Based Sources

Hover over each food below to see how much iodine you can get with one serving. Click on each food’s picture to visit its interactive page with a personalized calculator of all the nutrition you can get from one serving, more information about how it supports our body, tips to choose and prepare it, interesting facts, and more!

Nori

Nori

1 sheet (2g) = 36 mcg

Link
Dulse

Dulse

1 tsp flakes = 144 mcg

Link
Wakame

Wakame

1/4 c = 840 mcg

Link

Iodine Personalized Calculator

See how much iodine you and your family members need, according to the Dietary Guidelines for Americans, 2020-2025.

Terminology:

  • Daily Value (DV): The recommended amount of nutrients to consume each day for individuals who are 4 years old or older.
  • Recommended Daily Allowance (RDA): The recommended amount of nutrients to consume each day according to the individual’s age, gender, and whether a woman is pregnant or breastfeeding.
  • Upper Intake Level (UL): The highest amount of nutrient intake that will not pose adverse health effects on most individuals.

Important Things to Know

Hover over each of the interesting facts below to flip the tiles and learn more details.

Check out the interesting facts below! Tap on the red triangles to flip the tiles and learn more details.

Eating kelp regularly could lead to hyperthyroidism.

Kelp is very high in iodine content. Just 1/8 tsp has approximately 965 mcg of iodine, that’s over six times the RDA and above the UL for anyone under 18 years old. Keep in mind that iodine content varies by region, so the content could be higher. For this reason, adults should not consume kelp regularly and children should avoid it completely.

Salt is not a source of iodine unless it is iodized first.

In 1924, iodized salt hit the grocery shelves as a way to fight iodine deficiency. Today, however, other types of salt have become popular, such as sea salt or Himalayan salts. These salts are not typically iodized, and therefor are not a source of iodine. Processed foods do not typically use iodized salt either. If they do, it will be listed as such on their ingredients label.

Iodized salt offers about 45 mcg of iodine per 1 g of salt. That’s somewhere between 1/8 and 1/4 tsp.

Since high-sodium intake is detrimental to our health, the recommendation is to lower our salt intake and get our iodine from seaweed or supplements. However, if you’re still using salt when you cook, consider using iodized salt to maintain your family’s iodine levels in check.

Some fruits and vegetables may contain iodine.

Fruits and vegetables grown close to the sea may contain iodine because the soil in those areas is rich in iodine. However, this iodine content is not reported, so it’s not possible to know if you are getting proper amounts of iodine from these foods.

Iodine in dairy often comes from iodine-based disinfectants.

Dairy itself does not contain high amounts of iodine. In fact, when dairy is rich in iodine it’s either because the cows were given iodine supplements, or an iodine-based disinfectant was used on the cows and on the dairy production equipment. Iodine content in dairy can vary from 38 to 159 mcg/cup.

Pregnant women are at the highest risk of iodine deficiency.

The general U.S. population has adequate iodine intake, but a substantial portion of pregnant women is not getting enough, particularly those who are not consuming dairy, who are limiting their salt intake, or who are not taking iodine supplements since many prenatal vitamins do not include iodine.

We do not recommend dairy intake or ingesting more salt. However, it is important to up our seaweed intake or to take a reliable supplement to reach 220 mcg/day (read more about supplements below.) During lactation, we should aim at 290 mcg/day.

Iodine tincture is a common antiseptic used to clean wounds.

Iodine tincture is not the same as an iodine supplement. The tincture is typically made with 2-3% elemental iodine and sodium/potassium iodine, dissolved in a mix of water and ethanol (alcohol).

It’s often used to disinfect wounds, to prepare an area for surgery, and to disinfect water or produce. The amount needed to disinfect water is very small, only 5 drops per liter of water.

Elemental iodine can be toxic when ingested in larger amounts than what’s needed to disinfect water. So iodine tincture should not be considered as an option to supplement iodine intake.

Eating kelp regularly could lead to hyperthyroidism.

Kelp is very high in iodine content. Just 1/8 tsp has approximately 965 mcg of iodine, that’s over six times the RDA and above the UL for anyone under 18 years old. Keep in mind that iodine content varies by region, so the content could be higher. For this reason, adults should not consume kelp regularly and children should avoid it completely.

Salt is not a source of iodine unless it is iodized first.

In 1924, iodized salt hit the grocery shelves as a way to fight iodine deficiency. Today, however, other types of salt have become popular, such as sea salt or Himalayan salts. These salts are not typically iodized, and therefor are not a source of iodine. Processed foods do not typically use iodized salt either. If they do, it will be listed as such on their ingredients label.

Iodized salt offers about 45 mcg of iodine per 1 g of salt. That’s somewhere between 1/8 and 1/4 tsp.

Since high-sodium intake is detrimental to our health, the recommendation is to lower our salt intake and get our iodine from seaweed or supplements. However, if you’re still using salt when you cook, consider using iodized salt to maintain your family’s iodine levels in check.

Some fruits and vegetables may contain iodine.

Fruits and vegetables grown close to the sea may contain iodine because the soil in those areas is rich in iodine. However, this iodine content is not reported, so it’s not possible to know if you are getting proper amounts of iodine from these foods.

Iodine in dairy often comes from iodine-based disinfectants.

Dairy itself does not contain high amounts of iodine. In fact, when dairy is rich in iodine it’s either because the cows were given iodine supplements, or an iodine-based disinfectant was used on the cows and on the dairy production equipment. Iodine content in dairy can vary from 38 to 159 mcg/cup.

Pregnant women are at the highest risk of iodine deficiency.

The general U.S. population has adequate iodine intake, but a substantial portion of pregnant women is not getting enough, particularly those who are not consuming dairy, who are limiting their salt intake, or who are not taking iodine supplements since many prenatal vitamins do not include iodine.

We do not recommend dairy intake or ingesting more salt. However, it is important to up our seaweed intake or to take a reliable supplement to reach 220 mcg/day (read more about supplements below.) During lactation, we should aim at 290 mcg/day.

Iodine tincture is a common antiseptic used to clean wounds.

Iodine tincture is not the same as an iodine supplement. The tincture is typically made with 2-3% elemental iodine and sodium/potassium iodine, dissolved in a mix of water and ethanol (alcohol).

It’s often used to disinfect wounds, to prepare an area for surgery, and to disinfect water or produce. The amount needed to disinfect water is very small, only 5 drops per liter of water.

Elemental iodine can be toxic when ingested in larger amounts than what’s needed to disinfect water. So iodine tincture should not be considered as an option to supplement iodine intake.

Comparison of Iodine Sources

You may be wondering about other potential sources of iodine, such as supplements, dairy or seafood. Below we make a quick and simple comparison between your different choices.

Plant-Based
The only good plant-based source of iodine is seaweed. However, we could end up getting too much iodine from certain kinds, like kelp, and not enough from other kinds, like nori (unless we’re eating 3-4 large sheets a day.) So, choose your seaweed carefully.
Supplements
If you’re not eating seaweed regularly and you’re not cooking with iodized salt at home, taking an iodine supplement could be a good idea when following a vegan or a whole-foods, plant-based diet.
Supplements in the form of potassium iodide are recommended over kelp supplements because we absorb 98% of iodine from them, whereas we only absorb about half from kelp supplements.
Most importantly, though, iodine content in kelp supplements could be off by as much as 170% the amount reported on the labels, which means you could end up with excess iodine that could lead to hyperthyroidism. Also, arsenic and heavy metals have been found in kelp supplements.
Animal-based
A cup of dairy milk could contain from 38 to 159 mcg of iodine. However, dairy can promote IGF-1 production, which could lead to the growth of cancer tumors. Traces of estrogen from the cows may also cause hormonal cancers. Plus, dairy is high in saturated fats, which can lead to heart and brain issues, as well as diabetes type 2.
Seafood has a high content of iodine, but it is also highly polluted with microplastics and other toxins.
Eggs, also a potential source of iodine, are linked to cancer risk and acceleration.

References