Most vegans are aware that they need to pay extra attention to vitamin B12. But did you know that vegans need to keep iodine on the radar as well?
In this Dietitian written article, we’ll explore questions like:
Do vegans have low iodine levels?
What are iodine rich foods that are come from vegan sources?
Can you meet the RDA (Recommended Daily Allowance) without supplementing?
Disclaimer: Always consult your doctor if you have any health concerns or want to take a supplement. This article is not meant to treat, diagnose, or provide personal medical or dietary advice. See our Disclaimers for more details.
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Table of Contents
What Is Iodine?
Iodine is a essential mineral, meaning we must obtain enough from our diet to function optimally.
Why is iodine essential? Because it 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).
These hormones help regulate metabolism and other important processes.
Additionally, getting enough iodine in pregnancy and infancy is extremely important as it helps with proper development of the babies bones and brain.
The Recommended Daily Allowance
The RDA (Recommended Daily Allowance) for adults (individuals aged 19 years and older) is 150 mcg (micrograms) of iodine in the United States.
For pregnant individuals, the RDA increases to 220 mcg of iodine.
Lactating women need even more with an RDA of 290 mcg of iodine.
Remember how we mentioned iodine helps with proper metabolism? Because of this, if you are not getting enough iodine, you might develop unpleasant symptoms, some of which can take a toll on your energy.
Lets take a look at the symptoms and conditions associated with a potential iodine deficiency (Disclaimer: this is not a comprehensive list) Source: American Thyroid Association:
- Goiter: This refers to thyroid enlargement that may be visibly noticeable as lumps in the neck. Sometimes they can become very large.
- Problems for Children: As mentioned before, pregnancy and lactation are times when the body utilizes iodine more. If a pregnant mother does not get adequate amounts of iodine, her child may experience problems related to physical and intellectual development.
- Hypothyroidism: A condition that is often described as an underactive thyroid. Not getting enough iodine may cause this condition, but there are many other factors that may cause it as well.
Symptoms of hypothyroidism vary, and may include: weight gain, feelings of tiredness, problems getting pregnant or regulating periods, dry skin and hair, and difficulties with cold temperatures.
To learn more, check out the American Thyroid Association.
Ok, so we established that iodine deficiency can cause some problems, but what about iodine excess?
Lets tackle that question next.
Its 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 (Disclaimer: this is not a comprehensive list):
- Goiter: See the “Iodine Deficiency” section for more details.
- Hypothyroidism: More info in the previous section.
- Sensitivity Reactions
- Hyperthyroidism: A condition that occurs when too many thyroid hormones are produced.
Symptoms may include unintentional weight loss, sleep difficulties, irritableness, and muscle weakness.
Alright, now that we know too much and too little iodine has consequences, how does this apply to you as a vegan?
is vegan iodine deficiency a common problem?
Lets explore that next.
Iodine Intakes in Vegans: A Concern?
Unfortunately, we don’t have a lot of studies on the intake of iodine in vegans. And studies that use urine iodine concentration (UIC) to assess iodine intake might have limitations.
As you may recall, adequate iodine is crucial component to thyroid health. So this begs the question, do vegans have normal thyroid function?
One study on Boston area vegans and vegetarians suggests that the vegans had lower UIC than the vegetarians, however, both groups had normal TSH (thyroid stimulating hormone) levels, which is one measure used to assess the thyroid gland.
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!
In another small study looking at TSH levels in 48 vegans and 53 omnivores, 5 vegans had elevated TSH. However, 3 them reported taking kelp.
We need more and larger studies to provide a better idea regarding whether vegans are generally getting enough iodine.
Here’s what we do know: vegans avoid animal products.
However, vegan iodine sources do exist, and it is possible to meet the RDA with them.
But what are they?
And are there any downsides to them?
I am so glad you asked. That’s what our next section is all about!
Vegan Iodine Sources
Now that we know vegans should pay attention to iodine content, lets discuss vegan sources of iodine found in food:
1. Sea Vegetables
When we refer to the general term “sea vegetables” we are referring to edible vegetation from the sea. Common examples include (FYI: not a comprehensive list):
- Seaweed (ie: seaweed salad, nori (seaweed sheets often used in sushi or seaweed snacks)
While iodine content varies, its not uncommon to consume a lot of iodine in a small serving.
As you can imagine from the wide variability of iodine content, yes. There are some things you will want to consider.
For example, if you consume a lot of kelp flakes on a regular basis, you could set yourself up for iodine excess and associated health problems.
What’s more? One study suggests that certain seaweeds may contain high amounts of arsenic, and it can be difficult to tell the heavy metal content just by looking at the package.
We would love to see more research on the variability of iodine and arsenic content in sea vegetables.
Lastly, lets not forget the elephants in the room: accessibility and taste.
Sea vegetables are not the most assessable or affordable foods in North America.
Furthermore, as the use of edible sea vegetables is relatively new in the US, many may not be familiar with or accepting of the taste, which is often described as “fishy” for some.
Some vegans just don’t want to be reminded of that fishy taste, while others enjoy it!
Bottom line? These last two points may or may not present as potential barriers to vegans.
2. Iodized Salt
No your sea, pink Himalayan or black salt does not contain a significant amount of iodine, unless it has been iodized.
What does it mean for a salt to be iodized? Simply that the salt has some sort of iodide added to it.
Half a teaspoon of iodized salt contains about 155 mcg (105% the RDA for non pregnant non lactating adults)
This becomes especially relevant for vegans who cook with salt. However, if you rarely use salt, but eat processed foods, listen to this: Most of the salt used in processed foods is not iodized (at least not in the US).
For example, don’t rely on your store-bought veggie burger to provide adequate iodine, even if the ingredient list includes “salt.”
Again, not all salts contain iodine.
Even though half a teaspoon of iodized salt could meet or exceed the RDA (always check the label), there’s one nutrient that comes along with salt that many people avoid:
And for good reason! Too much sodium may increase your risk of hypertension, and hypertension increases your risk of heart disease – something we all want to avoid.
So 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. That’s a bit over half the American Heart Association’s (AHA) recommendation of no more than 2,300 mg for adults per day!
But that’s not it. The AHA also suggests moving toward an ideal limit of no more than 1,500 mg of sodium per day for most adults!
That means that if you included half a teaspoon of iodized salt each day, you would be at about 79% of your sodium intake already!
This doesn’t leave much room for foods that already contain sodium, like premade veggie burgers, frozen meals, bread, etc.
Bottom line: be mindful of your total sodium intake, especially if you are adding iodized salt to meet your iodine needs as a vegan.
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 7 mcg iodine, and a half cup serving of canned fruit cocktail in light syrup could provide about 6 mcg iodine.
Are there any iodine rich vegetables?
Vegan veggies, fruit, grains, and legumes were not included in our list because actual iodine levels may vary based on the iodine content in the soil and water. So we aren’t sure if these foods will be a reliable source of iodine.
For example, the iodine in potatoes may vary. The same goes for iodine in strawberries.
Secondly, from what we have seen, besides iodized salt, and sea vegetables, the majority of vegan foods appear to typically contain under 10% the RDA for iodine per serving.
However, one exception is bread made with iodate dough conditioner. A one slice serving of whole-wheat bread made with iodate dough conditioner may provide about 198 mcg of iodine.
Still, finding bread fortified with iodine is relatively rare in the United States, and whether or not these breads are vegan requires a detailed label check.
Should Vegans Take a Supplement?
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The answer is: it depends.
Talk to your doctor about any concerns you have about iodine.
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
- 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 vegan diets, and always consult your doctor before adding any supplement.
What Iodine Supplements Are Best?
Lets say your doctor gives you the ok to take a iodine supplement. He/she should tell you the correct dose to take, but what if you have the option between potassium iodine vs. kelp supplements?
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.
Talk to your doctor about the appropriate dose and source of iodine is best for you.
Vegan Iodine Myths
You Can’t Get Enough Iodine Without Supplementing As a Vegan
If you have read this far, you probably know by now: A fully plant based diet does not automatically mean a iodine deficiency, and iodine does exist in vegan foods.
Of course, if you are iodine deficient or have a thyroid problem, you may need more or less than the RDA. Plus, vegans do avoid some foods that are rich in iodine (ie: dairy and seafood), so talk to your doctor about diet and/or supplements if you are concerned or already have thyroid problems.
Plant Based “Milks” And “Cheese” Are a Good Source of Iodine
While there may be exceptions, this is largely a myth, at least in the United States.
Plant Based “milks” and “cheese” would need to be fortified to provide as much iodine as the dairy versions tend to have.
Unfortunately, iodine fortification is not required or widely used for vegan “milks” and “cheese” products in the US- as far as we are aware.
A Vegan Diet Causes Iodine Deficiency
We are not aware of any studies that show vegan diets directly cause iodine deficiency.
However, it is important to know how to get iodine on a vegan diet, and that consuming a lot of “goitrogens” may prevent iodine from being used by the thyroid gland, especially when iodine status is low.
Goitrogens include foods like soy, cassava, and cruciferous veggies, such as broccoli and cauliflower.
So does this mean we should avoid these foods whether we identify as vegan or not?
Unless your doctor tells you otherwise, getting an adequate amount of iodine, and not excessively over consuming goitrogenic foods should theoretically provide little impact on iodine status.
Final Thoughts: Vegan Iodine Sources
Some of the highest vegan iodine sources are iodized salt, and sea vegetables (such as nori). 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.
Being a vegan does not automatically mean you are deficient in iodine, but you should make due diligence to know your vegan iodine sources, and talk to your doctor about a supplement if you have any concerns.
Did this post clarify what vegan iodine sources are? Do you have any other questions about nutrients (ie: vitamin, minerals, macronutrients)? Leave us a comment below!
If you would like to learn more about keeping things 100% plant based, check out our post How to Transition To Veganism, Nutrition for Vegan Beginners, and Vegan Grocery Lists 101.
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