Your Thyroid + Iodine, Part 1

This post is the fourth installment in my ten-part Minerals and Your Thyroid series, where I’m highlighting eight thyroid-supportive minerals (iodine is two parts) and one troublemaker: fluoride.

Prior posts: Calcium, Copper, Iron

Click here for Part 2 of this 2-part Iodine series >

Iodine symbol: I
Atomic number: 53

I took a deep breath as I settled into my chair to begin writing this.

I’ve wanted to write a post about iodine for well over a year. But I’ve had analysis paralysis.

“Analysis paralysis is an anti-pattern, the state of over-analyzing (or over-thinking) a situation so that a decision or action is never taken.” – Source: wiki

Nary have I found a more wildly-challenged and wildly-supported health topic than whether those with hypothyroidism and Hashimoto’s should supplement with – or heck, even eat foods rich in – iodine.

According to this Forbes article, “…trying to stay up to date with the latest viewpoints and updates is akin to the human version of an information hamster wheel: you can run along it all day but never actually arrive anywhere. Rather, it’s up to you to decide when to stop.”

So today, I stop.

To, um, start, I don’t have the final word on iodine. I’m simply going to do my best to provide both sides of this hotly-contested story – one that I’ve gone cross-eyed trying to stay on top of.

But my “best” may not help you out of the “should I or shouldn’t I supplement with iodine?” conundrum that so many of our clients and readers find themselves in. But I will say that after a few years of no iodine supplementation and no iodized salt, based on my recent research, I’m back to some supplementation and using a little iodized salt. But that’s me.

How’s that for an introduction?

To Begin…
I’ll start by saying that some of the doctors and professionals I respect most are in different camps on the iodine controversy. The confusion is, hands down, one of the things I’m most often asked to provide clarity on. (Actually, it’s the second most frequent. This is the first.)

The thyroid’s job is to absorb iodine and combine it with the amino acid tyrosine. It then converts this iodine/tyrosine combination into T3 and T4. The thyroid produces some T3, the active hormone, but the majority is produced by the mostly inactive T4 by a process called T4/T3 conversion.

It’s true that the thyroid has the only cells capable of uptaking iodine. It’s also true that many who have Hashimoto’s are deficient in iodine, but the iodine deficiency isn’t the cause of their low thyroid function.

[I thoroughly address optimal thyroid nutrition in my best selling cookbook, The Essential Thyroid Cookbook: Over 100 Nourishing Recipes for Thriving with Hypothyroidism and Hashimoto’sThe educational component of the cookbook details not only thyroid-supportive minerals, but also vitamins and amino acids that help to optimize thyroid function. The mouthwatering recipes are chock full of these supportive nutrients.]

After all of the research, studies, reports, and examination that make it clear that upwards of 90% of hypothyroidism cases are a result of Hashimoto’s (autoimmune hypothyroidism), many doctors will still tell you that hypothyroidism is an iodine deficiency and will suggest iodine supplementation.

The percentage of non-autoimmune hypothyroidism (it’s really more like 3% vs. 10%) applies to the U.S.; worldwide, the most common cause of hypothyroidism is, in fact, iodine deficiency, although Hashimoto’s is on the rise all over the globe.

Lest you think I’m simply bashing conventional medicine, even some herbal or holistic/integrative practitioners still recommend the iodine-containing herbs bladderwrack or bugleweed for their hypothyroid clients/patients – sometimes without regard for the autoimmune component of an underfunctioning thyroid.

According to Chris Kresser (from my interview of him in 2012), “Non-autoimmune hypothyroidism is not an immune-mediated problem. It’s a problem with the thyroid itself and is often caused by an iodine deficiency or excess bromine exposure.” (More on bromine later.)

As we’re going to discuss, maintaining adequate levels of iodine is important – really important. Without it, your thyroid simply can’t do its job. But iodine – from food or supplementation – isn’t going to cure your autoimmune condition.

If only it were that easy.

Although some controversial doctors claim the contrary – that it will cure. Later, I’ll explain why I feel this is questionable and short-sighted.

Causes of Deficiency
According to the World Health Organization (WHO), 72% of the global population is affected by some manifestation of iodine deficiency.

Iodine insufficiency can result from:

  • Lack of iodine-rich foods in the diet, like seaweed and seafood (More on food sources later.)
  • Removal of iodized salt from the diet, either through overall reduction in salt intake or switching to sea salt, which contains trace minerals but no iodine
  • Iodine-deficient soil – iodine concentration in soil varies considerably by region, but it’s plentiful in the ocean; coastal regions tend to have higher soil iodine concentration due to absorption from the atmosphere
  • Fluoride in drinking water (More on fluoride in six weeks.)
  • Discontinued use of iodine to disinfect machinery in the dairy and meat industry

Again, worldwide, iodine deficiency is the leading cause of hypothyroidism but low thyroid function can also result from a goiter, which is an inflammatory enlargement of the thyroid gland. In parts of the world where iodine deficiency is prevalent, goiters are extremely common.

It’s less common to see iodine deficiency in the U.S., given that our salt (including salt in our canned, packaged, and fast food) is iodine-fortified. Dr. Richard Shames says that deficiency in the U.S. is “hardly the case.”

Prior to this fortification, iodine insufficiency was quite present (anyone heard of the “goiter belt?”).

You may think, “Wait, above, you said that hypothyroidism is a result of either Hashimoto’s or iodine deficiency. Or, as Kresser said, bromine exposure. And now you’re saying that it can result from a goiter.”

This is all true.

Hypothyroidism can also be triggered by stress, pregnancy, environmental toxins, Vitamin D deficiency, and your genetic propensity. And when you consider that in the initial stages, Hashimoto’s can be symptomless (usually before diagnosis), any one of these other triggers can tip the scales.

Speaking of goiters, some claim that excessive intake of “goitrogens” interferes with iodine uptake. We’re very pro-“goitrogen” (quotation marks intentional) and in our post on the matter, we state, “Because of their potential to affect iodine absorption, those of us with hypothyroidism may be inclined to avoid [goitrogens], but that would be a big mistake. These foods contain too many beneficial nutrients and are far too beneficial to the immune system to eliminate them. The evidence that such goitrogenic compounds pose significant risk to thyroid function is greatly suspect.”

We go on to quote Dr. Joel Fuhrman, who says, “Concerns about potential effects of cruciferous vegetables on thyroid function arose from animal studies, followed by findings suggesting that certain breakdown products of glucosinolates could interfere with thyroid hormone synthesis or compete with iodine for uptake by the thyroid. However, this is only a hypothetical issue. The scientific consensus is that cruciferous vegetables could only be detrimental to thyroid function in cases of iodine deficiency or insufficient iodine intake.”

Looking Back
Let’s take a journey back about five years. In early 2010, one prominent doctor claimed that supplementing with iodine was “like throwing gas on a fire” – that iodine supplementation would fan the flames (pun intended) of Hashimoto’s and increase antibody levels.

His best-selling book (I’m sure many of you know who I’m talking about) spread like wildfire (pun intended) through the integrative/holistic healthcare community.

And many well-respected and well-researched practitioners followed suit: writing, blogging, and educating about the dangers of iodine supplementation for those with Hashimoto’s.

I too followed suit. As I told my clients, “There aren’t many things I take a black and white approach to, but this is one of them. Don’t supplement with iodine – even kelp.” (More on kelp later.)

What ensued was another research project into finding a quality, food-based multi-vitamin with no iodine (or very little, for those who could tolerate it). For the record, I’m not convinced that everyone needs a multi-vitamin, but many of my clients feel they’re important, which I’m not going to argue with – indeed, they can be helpful.

Speaking of tolerating – I’ve certainly had many clients who’ve felt truly awful on iodine supplementation. So they were relieved to hear that I asked them to stop (if they hadn’t already) and after explaining the “fire” analogy, they then understood why they felt horribly.

The reason for this phenomenon is that, in theory, iodine supplementation increases thyroid antibodies. Anytime antibodies increase in a sudden or substantive way, the thyroid can temporarily dump thyroid hormones into the bloodstream and cause hyper symptoms. So yes, there can be a diagnosis of hypothyroidism/Hashimoto’s, but people can periodically swing into a hyper state that can include heightened anxiety, heart palpitations, sleeplessness, sweating, and shortness of breath.

According to Dr. Richard Shames, “How does excess iodine harm the thyroid? A high amount of iodine in the body becomes concentrated in the thyroid gland, in the hormone precursor protein called thyroglobulin. A high amount of iodinated thyroglobulin triggers an autoimmune response.”

Fast forward a couple of years.

I had a cluster of Hashimoto’s clients, all taking iodine supplementation, who claimed that it was a non-negotiable for them, that it helped them feel remarkably better and that if they didn’t take it, all bets were off – they’d feel awful.

Some had tried not taking iodine based on the well-publicized concerns, only to resort to taking it again and feeling more like themselves, with much more energy and focus.

The placebo effect? I don’t think so.

The claims couldn’t be ignored because these clients weren’t being thrown into a state of hyperactivity and feeling like they wanted to crawl out of their skin. That was undisputed.

And for many, their thyroid antibodies decreased significantly after starting iodine supplementation.

As they say, what’s one person’s remedy is another’s poison.

Although I knew I was in for more (much more) research around iodine, I was somewhat relieved. I don’t like black and white when it comes to food, nutrition, and supplementation. Sure, I want to tell all of my clients, “Do this, don’t do that,” but it’s rarely that straightforward.

It’s Not Just Thyroid Health
Although it’s the thyroid that typically comes to mind when many think of iodine, iodine has many other biochemical roles and iodine deficiency can cause tissue dysfunction in the:

  • Breasts
  • Brain
  • Thymus gland
  • Skin
  • Pancreas
  • Salivary glands
  • Eyes
  • Ovaries
  • Prostate

Iodine is also critical for preconception and pregnancy. According to Elizabeth Willett, fertility herbalist, “It is important to consume adequate amounts of iodine prior to conception and in pregnancy to avoid the serious complications for both the mother and the baby of iodine deficiency: high blood pressure during pregnancy (for the mother), mental retardation for the baby, cretinism (in extreme cases), which is a disorder that involves severely stunted physical and mental growth. The developing brain is most damaged by iodine deficiency.”

More on Breast Health
It was around the time that I had the group of clients who claimed to do very well with iodine supplementation that I began reading more about breast health as it relates to both thyroid function and iodine.

In short, both low thyroid function and iodine deficiency are linked to not only cystic breasts, but also breast cancer.

I could be wrong, but I feel that Dr. David Brownstein, who I’ve followed for a while, started beating the pro-iodine drum in response to the “never supplement with iodine” fire that spread like an ember landing on dry brush. The beat got louder when he wrote about the critical importance of iodine related to breast health, including hypothyroidism and breast health.

And that’s not all – he also claimed that thyroid hormone replacement is a risk for breast cancer, stating, “Studies have found a 200% increase risk of breast cancer in women who took thyroid hormone for at least 15 years as compared to women who did not take thyroid hormone. You read that correctly: a 200% increase risk …

“How could that be? The answer is simple: The increased breast risk in thyroid supplemented women is due to iodine deficiency. If the majority of the women were deficient in iodine, then taking thyroid hormone would be the wrong treatment. Thyroid supplementation increases the body’s metabolic needs and therefore increases the body’s need for iodine. If someone is iodine deficient and is prescribed thyroid hormone, thyroid supplementation will worsen the iodine-deficiency problem.”

Additionally, Dr. Christine Northrup talks about the critical importance of iodine for alleviating breast pain. As she states, “If you have breast pain, it’s likely you aren’t getting enough iodine.”

So with all of this, how could I continue telling my clients to categorically eschew iodine supplementation? In fact, I started supplementing myself. More on that later.

The Critical Factor
What differentiates those who can tolerate iodine from those who can’t? We’re all bio-individually unique, to be sure. There is no one-size-fits-all solution.

But one well-publicized discovery was that if you have an excess or deficiency in selenium, you’re likely to be intolerant of iodine supplementation. (More on selenium in four weeks.)

Mario Renato Iwakura is a Brazilian engineer and Hashimoto’s patient who is thoroughly well-versed in Hashimoto’s literature. If you want to geek out and get the hard science, you can find his two-part Iodine and Hashimoto’s Thyroiditis reports here: 1, 2.

In Part 2 of Renato Iwakura’s report, he states, “A survey of the literature suggests that Hashimoto’s is largely unaffected by iodine intake. However, the literature may be distorted by three circumstances under which iodine increases may harm, and iodine restriction help, Hashimoto’s patients:

  1. Selenium deficiency causes an intolerance of high iodine
  2. Iodine intake via seaweed is accompanied by thyrotoxic metals and halides (More on halides later.)
  3. Sudden increases in iodine can induce reactive hypothyroidism

“All three of these negatives can be avoided by supplementing selenium along with iodine, using potassium iodide rather than seaweed as the source of iodine, and increasing iodine intake gradually.

“It’s plausible that if iodine were supplemented in this way, then Hashimoto’s patients would experience benefits with little risk of harm. Anecdotally, a number have reported benefits from supplemental iodine.

“Other evidence emphasizes the need for balance between iodine and selenium. Just as iodine without selenium can cause hypothyroidism, so too can selenium without iodine. Both are needed for good health.”

Chris Kresser, who at one time strongly warned against iodine supplementation, later softened his view, stating, “A lot of studies show that selenium can protect against the potentially negative impacts of iodine supplementation for people who have autoimmune thyroid disease. So, if you do have Hashimoto’s or Graves’… and you’re considering taking iodine, you want to make sure that you’re getting at least 200 micrograms of selenium combined from food and supplements each day.” (More on dosing considerations later.)

As you can see, just like I talked about in my copper post with regard to the necessary copper/zinc correlation, it seems that there is a similar seesaw relationship or balance that needs to be present with iodine and selenium.

Iodine Displacement
Back to number two from above. What are halides? They’re chemical components of halogens. And iodine itself is a halogen.

According to Dr. Amy Myers, “Iodine is part of the halogen family, which also includes fluorine, chlorine, and bromine.”

Fluoride, which I’ll address more in six weeks, is the negative ion of fluorine. For now, know this, from Dr. John Douillard, “Since fluoride has become a ubiquitous part of our food and environment, low iodine levels in the body in combination with excess environmental fluorides may cause fluoride to uptake into the thyroid gland. From there, it may compete with iodine and act as an effective thyroid suppressant.”

Dr. Myers continues, “Fluorine, chlorine, and bromine are similar enough to iodine that your thyroid will suck them up and store them in place of iodine, effectively ‘displacing’ iodine.

“Of course, just because these chemicals look like iodine doesn’t mean they can be used to make thyroid hormones. If fluorine, chlorine, and bromine are displacing iodine, your ability to produce thyroid hormones is reduced, which can lead to low thyroid hormone levels and hypothyroidism. The higher the concentration of these chemicals and the lower your iodine levels, the more likely it is that your thyroid function will be negatively impacted.

“These three chemicals are now frequently added to our water, foods, and household products, and I believe this is one of the main reasons thyroid disease is now at an epidemic level.”

Bromine is something I really get on my high horse about and could really go off on right now.

The stuff is frickin’ awful. It’s a toxic halogen found in brominated flame retardants (found in carpet padding, mattresses, and electronics), pesticides and insecticides, soft drinks (especially Mountain Dew), and commercial baked goods (often labeled as “enriched flour”).

Chris Kresser states, “Bromine binds to iodine receptors and blocks the uptake and utilization of iodine. Even if you’re getting enough iodine, which most of us aren’t, you can’t use it.”

Polybrominated diphenyl ethers (PBDEs) are organobromine compounds used as flame retardants.

The most offensive use of flame retardants is in commercial mattresses – including crib mattresses. The toxicity is compounded by the fact that each time you lie down or sit on your mattress, the air inside bellows out. In other words, you inhale what your mattress exhales.

Sea Vegetables
There’s no doubt that sea vegetables are the highest source of iodine, with saltwater fish a close second.

Go here for safe seafood choices.

(And hey, for those of you in the Twin Cities, did you know about Kyatchi sushi restaurant and that they’re the first in the country to source all of their fish via the Monterey Bay Aquarium’s Safe Seafood standards?)

Sea vegetables are a good bang for your nutritional buck overall. In addition to iodine, they’re high in iron, calcium, phosphorus, manganese, copper, zinc, and a range of B vitamins.

They’re also great for liver detoxification and overall immune health. 

Here is a great resource for iodine-rich algae.

But here’s an important consideration. According to Renato Iwakura, “In Asia, high iodine intake is due to high consumption of seaweed. Seaweed is high in naturally produced bromine compounds, arsenic, and mercury, and can accumulate radioactive iodine. All these substances are known to interfere with thyroid function.

“It is quite possible that any benefits from ‘iodine restriction,’ i.e. seaweed restriction, [is] due to reduced intake of bromine, arsenic, mercury, and radioactive iodine.”

Nonetheless, I don’t have a problem recommending sea vegetables. I eat them in the form of kelp noodles, gomasio, and Seasnax.

It’s also a good idea to toss some kelp (aka kombu) into that gut-healing, skin-nourishing, inflammation-taming, immunity-boosting elixir known as bone broth. Here is our recipe.

Click here for Part 2 of this 2-part Iodine series, where I cover:

  • Supplementation: the dose makes the poison?
  • Iodine as the “double-edged sword”
  • The claims about the benefits of high dosing
  • The claims about the benefits of low – or no – dosing
  • Important considerations as you think about whether and how to supplement
  • Some supplement options
  • Testing for iodine deficiency
  • My personal approach and what I’m asking my clients to consider


Iodine is the hardest element of the equation when it cocmes to Hashimotos.
What if  your doctor is against the iodinie butit could save you or vice versa?
Is there a way to test it out?


Stay tuned for Part 2, next week. As far as what your doctor says, you always have to listen to your own inner wisdom. They’re not always right.

Jill, this is a fantastic article. Can't wait to hear about detoxing bromines, especially when people have had serious exposure to fluoride and chlorine. Thanks!

I hadn’t planned on addressing this in Part 2, but you pose a fantastic question – great fodder for another post. I’ll write about it at the end of this Minerals series. Deal?

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