Vegan Iodine Sources: What to Know From a Dietitian

Notable vegan iodine sources include iodized salt, sea vegetables, and vegan iodine supplements.

But are they healthy? What are the highest sources?

Don’t other fruits and veggies have iodine (and why do I need this nutrient anyways)?

Learn in this dietitian written article!

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Disclaimer: Always consult your doctor if you have any health concerns or want to take a supplement. This article is only providing education and is not providing personal medical or dietary advice. See our Disclaimers for more details.

This article was originally published on 1/12/22. The recent updated date is listed above.

Why Do Vegans Need Iodine?

Iodine is a essential trace mineral – meaning our bodies don’t make this necessary nutrient- so we have to get it in other ways! (btw – this goes for both vegans and those who don’t identify as vegan 😉 ) .

This mineral assists with the proper functioning of the thyroid gland (a hormone producing gland located in the neck). Specifically, iodine helps with the production of thyroid hormones thyroxine (T4) and Triiodothyronine (T3).

Thyroid hormones help regulate your metabolism and other important processes.

Additionally, getting enough iodine in pregnancy and infancy is extremely important as it helps with proper development of the baby’s bones and brain(1).

The Recommended Daily Allowance

The Recommended Daily Allowance (RDA) for adults (individuals aged 19 years and older) is 150 mcg (micrograms) of iodine per day.

For pregnant individuals, the RDA increases to 220 mcg of iodine per day.

Lactating women need even more with an RDA of 290 mcg of iodine per day(1).

Iodine Deficiency

If you don’t get enough iodine, you could develop a goiter (thyroid enlargement manifested as a lump in the neck) and/or hypothyroidism (an underactive thyroid).

Here are some symptoms associated with hypothyroidism (please note, this is not a comprehensive list. Always talk to your doctor about any health concerns):

• weight gain
• feelings of tiredness
• problems getting pregnant
• abnormal periods
• dry skin and hair
• unusual difficulty with cold temperatures(2).

Additionally, if a pregnant mother does not get adequate amounts of iodine, her child may experience problems related to physical and intellectual development(3).

To learn more, check out the American Thyroid Association.

Iodine Toxicity

It’s also important to make sure you don’t get too much iodine. Talk to your doctor about how much iodine is appropriate for you.

What are some symptoms of excess iodine? Here are some examples (again, not all symptoms may be listed)(4):

Alright, now that we know too much and too little iodine has consequences, how does this apply to you as a vegan?

Lets explore that next.

Iodine Intake in Vegans: A Concern?

Generally speaking, some research suggests that vegans might have lower iodine intake when compared to omnivores (we are going to talk about ideas to change that later, so stick around 😉 ).

One systematic review suggests that those who live in industrialized countries on a vegan diet, and do not consume seaweed or supplements with iodine may be most at risk (6).

Another study on Boston area vegans and vegetarians suggests that the vegans had lower UIC (urinary iodine concentration) than the vegetarians, however, both groups had normal TSH (thyroid stimulating hormone) levels, which is one measure used to assess the thyroid gland(7).

Of course this study was only looking at a relatively small group, and more/larger studies looking at iodine deficiency in vegetarians and vegans are needed.

Part of a 2023 systematic review and meta-analysis looked at dietary iodine intake among 678 participants with a vegan diet pattern compared to other diet patterns (strict raw, vegetarian, pescatarian, and omnivores), and suggests the vegan participants often had the lowest intakes of iodine comparatively.

The same 2023 study also compared UIC between 700 adult participants (diet patterns: vegan, vegetarian, pescatarian, omnivores, or flexitarian).

The vegan participants had the lowest UIC of all the groups, yet interestingly, none of the diet groups met the World Health Organization standards for optimal iodine status (8).

Again, it’s important to note the limitations of these studies (such as difficulties with accuracy in dietary recalls).

I’d also love to see more research comparing thyroid function in vegan participants to other dietary patterns.

Still, at this time, some research seems to suggest that vegans may have a harder time meeting the RDA for iodine, so it is very important to understand iodine sources, and ways to get enough.

This can be challenging for vegans because their options for high iodine containing foods might be more limited than omnivores.

For example, one of the of the major sources of iodine comes from non vegan dairy. This is because iodine may be in food/supplements for cows, and/the iodine containing sanitizing agents used in dairy production (although variable).

Certain types of seafood also contain varying amounts of iodine. But, again-vegans don’t eat animals.

So, where can vegans get iodine?

What should we keep in mind about consuming them? Let’s talk about that next!

Vegan Iodine Sources

Iodized salt and sea vegetables (FYI-sea vegetables can have varying levels), contain some of the highest amounts of vegan iodine.

Lets go into detail about each of them along with why you might want to consider a iodine supplement (FYI: always talk to your doctor before starting a supplement).

1. Sea Vegetables

‘Sea vegetables’ also known as seaweed, refers to edible vegetation from the sea in this article. Common examples include (FYI: not a comprehensive list):

• nori (seaweed sheets often used in sushi or seaweed snacks)
• Wakame
• Kelp
• Dulce

It’s important to note that depending on the source, and iodine concentration in the sea, the amounts of iodine may vary widely.

Its not uncommon to consume a lot of iodine in a small serving.

For example, a tiny one gram serving of nori may contain about 16 mcg , while a kelp flakes could contain over 8,000 mcg of iodine in that 1 gram serving(9)!

With that amount of iodine, you can easily see how you could set yourself up for iodine excess and health problems. Things you don’t want.

Also, sea vegetables aren’t readily accessible to all in North America. They can be expensive as well.

Taste can be another potential barrier too. Sea veggies are sometimes described as “fishy” (a flavor some vegans want to avoid!) .

Bottom line: because there is so much variability from sea vegetables- relying on them to meet your iodine needs may not be the best choice.

A more reliable source would be an quality iodine supplement that is not too high in iodine (again, always discuss with your doctor before taking a supplement), or iodized salt -keeping sodium and other medical conditions in mind.

Which brings us to our next vegan source high in iodine…

2. Iodized Salt

Pink himalayan, sea, black and even several table salts, do not contain a significant amount of iodine. The salt must be labeled as iodized salt in order to contain a decent amount of iodine.

Iodized salt has iodine added to it, about 155 mcg in half a teaspoon(10) (this will vary-so check the nutrition facts label) This is around 103% the RDA for non pregnant and non lactating adults.

This becomes especially relevant for vegans who season with iodized salt. However, if you rarely use salt, but eat processed foods, listen up: Most of the salt used in processed foods is not iodized (at least not in the US).

For example, your store bought veggie burger may have sodium, but it’s unlikely to contain iodized salt.

if you are a vegan who wants to use iodized salt as your primary source of iodine know this:

Half a teaspoon of iodized salt contains about 1,180 mg (milligrams) of sodium(10). That’s a bit over half the American Heart Association’s (AHA) recommendation of no more than 2,300 mg of sodium for adults per day (and the AHA even suggest the ideal sodium limit might be more like 1,500 mg of sodium per day for adults)!

Bottom line: be mindful of your total sodium intake, especially if you are adding iodized salt to meet your iodine needs as a vegan.

Too much sodium may increase your risk of hypertension, and hypertension increases your risk of heart disease – something we all want to avoid(11).

As an alternative option, vegans can talk to their doctor about adding a quality iodine supplement that is not too high in iodine (we’ll get to supplements soon).

Are Those Really All The Vegan Foods That Contain Iodine?

Well, not technically.

There are many vegan foods that contain some iodine. For example, a 1 cup serving of a soy beverage may provide about 3 mcg of iodine, and a half cup serving of canned fruit cocktail in light syrup could provide around 5 mcg of iodine(12).

If you’ve been paying attention, these sources aren’t likely to make a huge dent in your iodine intake.

That’s because the iodine content in fruits and veggies is variable depending on the iodine in the soil and water(13).

I can’t tell you that your potatoes or strawberries are a good source of iodine, so don’t rely on them to meet all of your iodine needs with confidence.

One exception is bread specifically made with iodate dough conditioner (check the label). A one slice serving of whole-wheat bread made with iodate dough conditioner may provide about 140 mcg of iodine(14).

However, finding bread fortified with iodine is rare in the United States, and these breads might not be vegan.

Now, some countries may have had iodine fortification to certain vegan products, but as far as I’m aware, these products are hard to find, and you really need to read the nutrition facts to see if they are fortified with iodine (15).

Should Vegans Take a Supplement?

The answer is: it depends.

Talk to your doctor about any concerns you have about iodine and whether a supplement would be a good option.

Whether or not you will need vegan iodine drops or supplements depends on a variety of factors such as (Disclaimer: not a complete list):

• The iodine content in your diet
• Health conditions
• Medications
• The region you live in

If you want to get a sense of iodine levels in your diet, consider using a nutrient tracking app, such as Cronometer (affiliate link*) to track your intake.

Remember though: no tracking app is perfect, improper use can skew results, and some nutrient levels may be inaccurate. Talk to a Registered Dietitian about other ways to assess your iodine intake from your vegan diet, and always consult your doctor before adding any supplement.

What Iodine Supplements Are Best?

One study looked at kelp supplements, and discovered certain brands may contain a lot more iodine than is listed on the label. For this reason, the study suggests kelp supplements should generally be avoided, and to look for supplements that use potassium iodine instead(16).

That being said, talk to your doctor about the appropriate dose and source of iodine is best for you. Some medical conditions may require a certain form of iodine, and accessibility is also another factor to discuss.

Additionally, vegan multivitamins may contain iodine, make sure you discuss that as well.

Vegan Iodine FAQ

Are Processed Plant Based Products a Good Source of Iodine?

The vast majority of processed plant based products, like “vegan milks” are not currently fortified with iodine in the United States.

There may be exceptions, so check out the ingredients and nutrient labels.

Does a Vegan Diet Causes Iodine Deficiency?

We are not aware of any studies that show vegan diets directly cause iodine deficiency.

Still, it’s important to know how to get iodine on a vegan diet.

When iodine intake is low, consuming a lot of foods labeled as goitrogens (such as soy, cassava, and broccoli) may prevent iodine from being used by the thyroid gland(17).

So make sure you are getting an appropriate and adequate amount of iodine!

Final Words

Some of the highest vegan iodine sources are iodized salt, and sea vegetables (although, iodine levels will vary). Vegan iodine supplements are also available.

If you are concerned about your iodine intake, talk to your doctor. He/she may order some labs that test your levels of certain thyroid hormones. Your doctor can help you determine if a iodine supplement is appropriate.

Did this post clarify what vegan sources of iodine are? Do you have any other questions? Leave us a comment below!
If you would like to learn more about keeping things 100% plant based, check out our articles!
We talk about subjects like Vegan Food Sources of…:
Vitamin B12
Biotin
Beta Carotene (a precursor to vitamin A)
Fats
High Calorie Vegan Foods
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