Iodine is a controversial topic with regard to thyroid health, and while I discussed the dangers of high doses of iodine for Hashimoto’s in my book, Hashimoto’s the Root Cause, I have not yet written a post about iodine publicly, as I wanted to make sure that the conversation didn’t turn into a debate about a single nutrient when Hashimoto’s is a multi-factor and full body condition.
However, this question keeps coming up, and I have seen iodine harm people with Hashimoto’s, so I feel the need to make this cautionary post about using iodine with Hashimoto’s.
A reader wrote:
“I was given Iodine for a short spurt and my TSH went up to 98 and my antibodies up to 9800 after about 3 months. I think it can be deceiving. I would only do it with a doctor who understands the delicate balance with selenium. I regret that time in my journey now. It was with someone who did the simple iodine test on the hand and determined the dosage by muscle testing. I would not advise that for others.”
I wish it was a one time report—any supplement can have an adverse reaction—but I have received countless messages like the one above and have seen many similar reports in clients who came to me after trying high dose iodine on their own or with other practitioners.
Initially, the person has more energy, but they then crash and feel worse… This is because iodine given to a subset of people with Hashimoto’s can flare up the attack on the thyroid gland. Iodine needs to be processed by the thyroid gland, and when the thyroid is inflamed, the processing of iodine will likely produce more inflammation. You give an angry and overwhelmed organ more work to do, and you’ll likely see it become even angrier! (5)
A person may feel more energetic when first starting an iodine supplement, but lab tests will reveal that their “new energy” is coming from the destruction of thyroid tissue which dumps thyroid hormone into the circulation, and reports will show an elevated TSH, elevated thyroid antibodies, and in some cases, low levels of active thyroid hormones. This is why I don’t generally recommend iodine supplements to people with Hashimoto’s. I don’t believe that the short-term artificial boost in energy is worth destroying your thyroid gland! (5)
High Doses of Iodine Can Harm Hashimoto’s
Scientists have long known that iodine is a crucial nutrient for thyroid health. In fact, iodine deficiency is the primary reason for hypothyroidism worldwide. In an effort to reduce the incidence of hypothyroidism, public health officials began adding iodine to the salt supplies in many industrialized countries. However, this effort backfired, as iodine turned out to be a narrow therapeutic index nutrient. While a deficiency of iodine created hypothyroidism due to a lack of building materials for thyroid hormone, an excess of it also created hypothyroidism, but through a different mechanism. Today, iodine excess is recognized as a risk factor for developing autoimmune thyroid disease.
This has to do with the way that iodine is processed in the body. Iodine from foods and supplements is processed by the thyroid gland so that the body can properly use it. During this process, hydrogen peroxide, a free radical, is released. In cases when the body has adequate levels of selenium and it is used properly, the selenium neutralizes the hydrogen peroxide. However, in cases of iodine excess, excess hydrogen peroxide can cause oxidative damage to the thyroid gland. (4)
Studies have shown that excess iodine causes thyroid injury by generating reactive oxygen species, which lead to premature damage and programmed cell death in thyroid tissues. These iodine-overloaded cells then release the danger (or damage)-associated molecular patterns (DAMPs) which turn on the autoimmune process in a person with the right genetic predisposition and intestinal permeability. When we think about this from an evolutionary, adaptive, or even innate body wisdom stance, this makes sense that the body would want to stop the production of excess thyroid hormones that would result from too much iodine. [Read my article on my Safety Theory that explains Why Women Have More Thyroid Disease]
While some thyroid advocates will propose that taking high doses of iodine is helpful for everyone with Hashimoto’s, I have not seen this to be the case.
Research has shown that high doses of iodine can trigger Hashimoto’s in people who are genetically predisposed to Hashimoto’s and may perhaps have certain “vulnerabilities” like a selenium deficiency. (1)
Taking a high dose of iodine can exacerbate Hashimoto’s and accelerate thyroid cell destruction. The American Thyroid Association cautions against using doses of more than 500 mcg per day in the general public and noted that doses above 1100 mcg may cause thyroid dysfunction. These warnings are for the general population, but studies have found that people with Hashimoto’s may be sensitive to even smaller doses.
Should You Avoid Iodine Completely?
In Germany, a low dose of potassium iodide (250 mcg) was given to forty people who tested positive for anti-thyroid (TPO) antibodies or had a thyroid ultrasound showing a hypoechogenic pattern consistent with Hashimoto’s. A group of forty-three subjects with similar characteristics served as a control group. Nine patients from the iodine group developed thyroid abnormalities, compared with only one person from the control group. Of the nine patients in the iodine arm, seven developed subclinical hypothyroidism, one became hypothyroid, and another hyperthyroid. Changes were also seen in TPO antibody levels as well as on the thyroid ultrasound. Three of the seven subclinical hypothyroid patients and the hyperthyroid patient regained normal thyroid function after iodine withdrawal.
While there is a bit of controversy about whether people with Hashimoto’s should take iodine or avoid it altogether, a 1999 study in 377 people with Hashimoto’s followed for over 800 days found that when combined with thyroid hormone therapy, a daily iodine dose of up to 200 mcg/day was able to reduce the TgAb and the TPOAb levels even in patients with Hashimoto’s thyroiditis. (3)
However, the same study also enlisted a group of 375 people without thyroid disease and gave them either 200mcg per day of iodine or 1.53 milligrams of iodine per week. The group that took 200 mcg per day did not have a significant increase in rates of Hashimoto’s. However, the group that got the large dose of iodine/week presented a distinct increase of the TgAb as well as the TPOAb, and the incidence of Hashimoto’s thyroiditis was 4-fold higher than in the two other subgroups! (3)
This study showed that a low dose of iodine on a daily basis is usually not going to be problematic for people with Hashimoto’s, and in fact may be beneficial. (3) However, I would caution against using a dose above 200 mcg/day unless breastfeeding or pregnant (the general recommended daily allowance of iodine is 150 mcg for non-pregnancy and 220 mcg and 290 mcg for pregnant and breastfeeding women respectively). This includes your intake from supplements as well as high iodine-containing foods like seaweed, kelp, spirulina, or chlorella. If exposed to these high doses of iodine, it may be helpful to take a selenium supplement (up to 600 mcg per day) to negate the negative effects of the iodine excess.
In some cases, a low iodine diet has been helpful in reducing the autoimmune attack on the thyroid gland and in normalizing thyroid function in people with iodine-induced Hashimoto’s. In this case, a person would temporarily restrict iodine to <100 mcg per day for a period of 1-3 months (the thyroid gland needs approximately 52 mcg per day of iodine which is usually present in thyroid hormones which contain a small amount of iodine in them). For more information about the low iodine approach, please see my first book Hashimoto’s Thyroiditis: Lifestyle Interventions for Finding and Treating the Root Cause. (2)
Real World Experience with Iodine
Out of my Root Cause Readers that were surveyed, 356 tried high dose Iodine. Out of that group, 25% said that high dose iodine made them feel better, 28% said that it made them feel worse, and 46% saw no difference in how they felt…although this doesn’t mean that their thyroid markers weren’t affected. The takeaway from this survey is that more people felt worse on high dose Iodine than felt better. On the other hand, iodine restriction made 31.7% feel better and 7% feel worse.
In contrast, taking a selenium supplement helped 63% feel better, 34% saw no difference, while 3.5% felt worse. And going gluten free helped 88% of people feel better, 11.16% saw no difference, and 0.73% felt worse.
As you can see, there are many safer and much more effective interventions than iodine supplementation in Hashimoto’s, which is why I have chosen to focus on the interventions that are helpful to most and least likely to result in harm. I treat iodine like a narrow therapeutic drug and recommend caution when using it in Hashimoto’s.
I do not routinely recommend the use of iodine supplements outside of those found in multivitamins and prenatal vitamins (most contain between 150 mcg-220 mcg). While I won’t deny that some people have certainly been helped by high dose iodine, I feel that the risks outweigh the benefits for people with Hashimoto’s, and I caution people against the use of high dose iodine. In those who have been exposed to high doses, I may even recommend a short-term iodine restriction.
Hashimoto’s – It’s a Whole Body Condition, Not Just a Thyroid Condition
From Dr. Izabella’s Client Files
Jenny is an athletic dog lover who worked part at her family restaurant. She had been previously diagnosed with Hashimoto’s (TPO antibodies in the 800 range) and subclinical hypothyroidism, with a slightly elevated TSH, and normal T4 and T3.
At her initial diagnosis, Jenny had many symptoms of hypothyroidism including fatigue, excess weight gain, and hair loss.
She wanted to fix the condition in a natural way and found information about iodine being an effective treatment for hypothyroidism. She worked with an iodine advocate who did not have a medical background but had seen improvement in her own thyroid function with iodine, although she herself had never been diagnosed with a thyroid condition. This advocate recommended that she start taking high doses of iodine to heal her thyroid.
After starting the high dose iodine, Jenny began to have more energy, but soon that energy became an anxious, irritable energy. She then became very tired, to the point where she stayed in bed for days.
Jenny’s husband became concerned about her health and urged her to stop working with the iodine advocate and see an endocrinologist who ran a thyroid antibody test—her thyroid antibodies had more than doubled to the 1800 range, her TSH climbed to 100, and her T4 levels were undetectable! Her physician advised her to stop the high dose iodine immediately and prescribed synthetic thyroid medications.
After that point, Jenny came across my book and reached out to me for a case review. Her husband felt more comfortable with her consulting with me since I had a background in pharmacy and had also been diagnosed with Hashimoto’s.
I recommended that she restrict her intake of iodine from iodized salt, supplements, and food to less than 150 mcg of iodine per day for three months and that she start the Paleo diet. I also recommended for her to start a selenium supplement, probiotics, test her adrenals through a saliva test, and test for gut infections through a stool test. In addition, I advised her to speak to her doctor about adjusting her medications.
Within a few weeks of the new protocol, Jenny was starting to feel better. The anxiety and irritability improved, and her fatigue began to lift.
Once we received her test results back, we found that Jenny had stage 3 adrenal fatigue, and two gut infections; H. pylori and Blastocystis hominis. [READ MORE ABOUT BLASTO]
We talked about the importance of self-care, and I recommended that she reduce her responsibility levels and that she start massage therapy treatments and a relaxing routine. We supported her adrenals though the use of adrenal adaptogens and a supplement called Moducare.
We also worked with her physician and treated her gut infections, starting with H. pylori, and then Blastocystis hominis. We then initiated a gut repair protocol. [All of these protocols are in Hashimoto’s Protocol and in the H. pylori and Blasto articles.]
Jenny reported that her gut symptoms, hair loss, and energy levels began to improve within two weeks on the H. pylori protocol. After she finished her protocol, her weight normalized, and she reported that she had a “ton of energy,” and her hair began to grow back. Her thyroid medications had to be lowered slightly as she began to absorb them better once the infections were gone. [READ MORE ABOUT H. PYLORI]
The last time we spoke was 6 months after her gut infection treatments, and she reported feeling happy, having great hair, great energy levels and was back to being active and working out 4-5 days per week. Her TPO levels fell to under 100, and I anticipate that they will continue to improve as time goes on (TPO levels may take 3 months to 18 months following H. pylori eradication).
Could You Have Hashimoto’s and Be Deficient in Iodine?
In my experience, Hashimoto’s is not a single nutrient deficiency, and thus, it cannot be resolved by using a single nutrient in most cases. That said, it’s possible, though not necessarily common, to be deficient in iodine when you have Hashimoto’s.
I often get the question about testing for iodine deficiency—do blood tests, urine tests or “spot” tests (where you paint yourself with iodine until it disappears) actually work? Are they accurate? Unfortunately, to the best of my knowledge, the tests are not able to reveal an iodine deficiency or excess, rather they will be reflective of your recent iodine intake.
Some potential things that may lead me to suspect an iodine deficiency include: eating a vegan diet, eating a diet low in seafood, fibrocystic breasts (though this could be caused by magnesium deficiency), low reverse T3 on a lab test, or a negative reaction to selenium (which is very rare).
In the case of a deficiency of iodine, I do recommend iodine supplements but only in the dose range found in multivitamins and prenatal vitamins (most contain between 150 mcg–220 mcg). If you are deficient in iodine, an iodine supplement will likely help your symptoms and may improve your outcomes, but it is not likely to be a cure-all!
If you are pregnant or breastfeeding, I do recommend a prenatal vitamin that contains iodine.
High Iodine Foods
Kelp, dulse, spirulina, chlorella, or seaweed, may also contain high doses of iodine, and I recommend avoiding them if you have elevated thyroid antibodies. Furthermore, I recommend avoiding the use of iodized salt. A diet I do recommend trying on your healing journey is the Autoimmune Paleo diet. Click here to get your free recipes!
The Bottom Line
- Excess iodine has been recognized as an environmental trigger for Hashimoto’s
- Hashimoto’s is not a single nutrient condition…and most people with Hashimoto’s are not iodine deficient
- The dose range found in multivitamins and prenatal vitamins (most contain between 150 mcg–220 mcg) is generally safe for people with Hashimoto’s
- For my recent article on the nutrients that are helpful in Hashimoto’s- please read The 6 Most Important Nutrient Deficiencies in Hashimoto’s
I hope this information helps you on your journey.
What type of experience have you had with iodine?
- Contempre B, Dumont J, Ngo B, et al. Effect of selenium supplementation in hypothyroid subjects of an iodine and selenium deficient area: the possible danger of indiscriminate supplementation of iodine-deficient subjects with selenium. J Clin Endocrinol Metab. 1991;73(1):213-215. doi:10.1210/jcem-73-1-213.
- Joung J, Cho Y, Park S, et al. Effect of iodine restriction on thyroid function in subclinical hypothyroid patients in an iodine-replete area: a long period observation in a large-scale cohort. Thyroid. 2014;24(9):1361-1368. doi:10.1089/thy.2014.0046.
- Rink T, Schroth H, Holle L, Garth H. [Effect of iodine and thyroid hormones in the induction and therapy of Hashimoto’s thyroiditis]. <Nuklearmedizin. 2016;1999(38(5):144-9.
- Xu J, Liu X, Yang X, et al. Supplemental selenium alleviates the toxic effects of excessive iodine on thyroid. Biol Trace Elem Res
- Zhao H, Tian Y, Liu Z, et al. Correlation between iodine intake and thyroid disorders: a cross-sectional study from the south of China. Biol Trace Elem Res. 2014;162(1-3):87-94. doi:10.1007/s12011-014-0102-9.