Iodine is vital for proper thyroid function. The top sources of iodine are foods from the sea and iodized salt, followed by milk and eggs. Dr. Michael Greger explains how to ensure adequate iodine levels on a plant-based vegan diet, as well as the dangers of getting too much iodine.
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Iodine may not immediately be on your radar as a nutrient of concern when going vegan—it’s a non-metallic trace element that most people think of in terms of its use as a pre-surgical topical application.
However, dietary iodine is key to the synthesis of thyroid hormones crucial for multiple functions such as metabolism and, during pregnancy, fetal development.
The top sources of iodine are foods from the sea and iodized salt, followed by milk and eggs. So, what is a vegan to do?
Dr. Greger is a licensed general practitioner specializing in clinical nutrition, an author, and an internationally-recognized speaker on nutrition, food safety, and matters of public health.
This interview is the eighth in the Vegan Nutrition Concerns Series with Dr. Greger. This series addresses common nutrient-specific concerns related to a plant-based diet, and touches upon the health impacts of animal products.
The following transcript of my interview with Dr. Greger (from the video above) is edited for clarity, order, and readability.
Dr. Greger: Iodine is important for thyroid function. It’s found predominantly in the ocean and, [in] variable amounts, in the soil around the world. But it kind of depends where you’re growing your food.
Back in the 1920s, they iodized the salt supply and so [you can get iodine from salt] if add [iodized] salt to your food (not sea salt, or mineral salt, or crazy Himalayan salt…[which has] 20 times less iodine than iodized salt. But of course, we shouldn’t be adding salt to our foods at all. Sodium is considered the third leading dietary killer in the United States.
Some people can get [iodine] from seafood because it’s found in the ocean. And also, [for] people that drink dairy milk: [iodine is] actually not in the milk itself, but it’s used in these iodine-containing disinfectants…called “teat dips,” [used] to prevent mastitis. They dipped the cow’s teats in an iodine-containing solution like beta dye, and some of that iodine then leaches into the milk.
Dr. Greger: For people who are eating healthier diets…you may be getting all that you need just from eating land plants depending on where the plants are grown.
But I would [also] encourage people to develop a taste for sea vegetables, kind of the dark green leaves of the sea. [F]or example, a half teaspoon of dulse…or arme, is all the iodine you need for the day: there’s 150 mcg.
And…you can get [dulse] in these little purple flakes…so, you can sprinkle a half-teaspoon on whatever you are eating and you wouldn’t even know it’s there. You can get all that you need [that way]. And also, it [has] other good, wonderful trace minerals.
I would not, however, encourage people to eat hijiki, which has too much arsenic, and kelp actually has too much iodine. So, it’s very difficult to…get your iodine from kelp just because it’s so concentrated, you’d need to take such small amounts. And so, with those two [sources] aside, I encourage people to eat sea vegetables.
Dr. Greger: There’s a lot of great seaweed snacks on the market now…like nori sheets, the sushi sheets and their flavored varieties. Now, unfortunately most of them have added oil and salt, but you go get a big thing of nori sheets.
And what I like to do…there’s lots of ways you can season them, [but] I kind of paint them, brush them with pickled ginger juice from pickled ginger for sushi. [T]hen [I] just sprinkle some wasabi powder on it, which is actually a cruciferous vegetable — it’s horseradish. And then [I] re-crisp it in the oven [at] about 300 degrees for 5 minutes [or so], and get a really delicious snack.
And so, you can just sit there on the couch eating seaweed snacks, [with] no added sodium, and as a snack you’re eating dark green leafy vegetables. [It’s] like eating kale chips…you can’t get healthier than that, and you get all the iodine you need.
A note of caution from Dr. Greger: You do not want to get too much iodine. Don’t go over a tablespoon of the dulse or more than 10 sheets of the nori seaweed every day, because you can actually [develop excess] thyroid function.
The other thing is [that iodine is] particularly critical during pregnancy, so I agree with the American Thyroid Association’s recommendation that all women, regardless of what they eat, get as part of their multi-vitamin regimen 150 mcg of iodine everyday.
I hope you enjoyed hearing from Dr. Greger on the topic of how to get iodine on a vegan diet.
Our actual iodine requirements are incredibly low, with our dietary needs over an entire lifetime fitting within one teaspoon. However, iodine deficiency is prevalent in some countries where there are either low sea and soil levels of iodine and/or if one is eating a purely refined-foods diet.
Of course, diets high in iodized salt and fortified foods can lead to iodine toxicity, so it’s best to stay below the upper limit of 1,100 micrograms a day.
Because of the variation of soil and sea iodine content around the world, a standard iodine content for most foods does not exist. So, please be mindful of its amount in what you are eating.
I’d love to hear from you on this topic! Do you have concerns about iodine in your diet? Have you experienced any thyroid issues linked to iodine? Has being vegan impacted this? Let me know in the comments!
— Emily Moran Barwick
Please note that when it comes to your health and nutrition, there is no substitute for the guidance of a trained medical professional, especially if you have any medical conditions or complications.
Finding a plant-based provider can be challenging, depending on your location and health insurance (or lack thereof). In the accordion below are online directories for plant-based providers. I hope to expand the list to include ones that serve more countries. If you know of any additional directories, please let me know!
Plant-based medical provider directories
Please note: in listing these directories, I am not recommending or endorsing them or any health care providers listed within them.
- The Physicians Committee for Responsible Medicine (PCRM) (Worldwide)
- Plantrician Providers (U.S.)
- Plant-Based Health Professionals (UK)
- Plant-Based Canada (Canada)
- Vegan Friendly Registered Dietitians (Worldwide – telehealth) from Challenge22
Do you know of other directories? Especially ones serving more parts of the world? Please let me know!
MORE FROM THE VEGAN NUTRITION CONCERNS SERIES:
- The Crime Of Raising Vegan Kids | When Diet Is Deadly
- How NOT To DIE: Foods That Add Years | Dr. Michael Greger
- Deadly Nutrition: The REAL Dietary Killers | Dr. Michael Greger
- How to Get Carnitine, Carnosine & Creatine on a Vegan Diet | Dr. Michael Greger of Nutritionfacts.org
- How to Get Zinc on a Plant-Based Vegan Diet | Dr. Michael Greger of Nutritionfacts.org
- How to Get Vitamin B12 on a Plant-Based Vegan Diet | Dr. Michael Greger of Nutritionfacts.org
- How to Get Vitamin D on a Plant-Based Vegan Diet | Dr. Michael Greger of Nutritionfacts.org
- How to Get Iron on a Plant-Based Vegan Diet | Dr. Michael Greger of NutritionFacts.org
- How to Get Calcium on a Plant-Based Vegan Diet | Dr. Michael Greger of Nutritionfacts.org
- How to Get Omega-3 on a Plant-Based Vegan Diet | Dr. Michael Greger of Nutritionfacts.org