Excess Iodine and Thyroid Disease

Did you know that modern diets are more likely to contain too much iodine than too little, and that excess iodine is a known risk for thyroid disease, which is alarmingly common? Table salt has iodine added to it, but what might surprise you is that eggs and dairy now contain too much iodine. The excess iodine in eggs and dairy get there from the chicken’s or cow’s feed, which is usually supplemented with iodine, and for dairy, from the iodine based disinfectants used on the udder and on the dairy equipment. That’s right, there is probably a significant amount of chemical disinfectant in milk.

Here’s a video from Dr. Alan Christianson that talks about this:

I was surprised to learn all this. I found it out because I had a blood test that showed I had high thyroid antibodies (TPO Ab) which produce a version of hypothyroidism called Hashimoto’s disease. I found research that stated strongly that excess iodine is linked to Hashimoto’s, probably because the iodine damages the thyroid and so the body deploys its TPO Ab antibodies to clean up the damaged tissue.

When I found this out, I switched from iodized salt to non-iodized salt right away, and my symptoms began to improve that very day. Thyroid function can be measured pretty well by tracking your body temperature. My temperature was 1.5 degrees too cold all the time because my thyroid wasn’t working so well. But when I removed the iodized salt (starting at breakfast) my body temperature was up 0.5 degrees higher than typical that evening and I had a lot more energy and mental quickness!

After that, I switched the milk in my diet to cheese, which typically has a lot lower iodine but a similar amount of calcium and vitamins as milk. (By the way, yogurt and whey protein powder are both high iodine too. Whey protein might have even more than milk.)

Have you heard that, contrary to what I’m saying here, that iodine intake today is too low and that we should actually greatly increase our iodine consumption? That idea is popular today, but I believe it is incorrect and often dangerous. Discussion of this can be found here from Dr. Izabella Wentz and here from the Weston A. Price Foundation. And here’s another video interview that you may find helpful.

A bunch of statistics, studies, and notes on iodine, the thyroid, and thyroid disease

Here’s a great article showing iodization causes Hashimotos. “Starting with the first decade after iodine fortification, they [in Minnesota] documented a 2,500 percent increase in Hashimoto’s disease.”

“[In Denmark] prior to iodization of salt [which started in 1998], the prevalence of anti-TPO antibody (anti-TPO-Ab) was 14.3%, but increased to 23.8% after iodization […] In a small Italian community, voluntary iodine prophylaxis increased the incidence of anti-TPO-Ab and hypothyroidism 15 years later.” https://pmc.ncbi.nlm.nih.gov/articles/PMC5422478/

In Iran, salt was iodized in 1994. Before that, in 1983-84, thyroid antibodies were found in 4% of people. After iodization, in 1999-2000, thyroid antibodies were found in 16.8% of people. https://thyroidpharmacist.com/articles/iodine-hashimotos/

“Several hypotheses have been proposed to explain the association of excessive iodine consumption and thyroid autoimmunity. First, iodine may be directly toxic to thyroid tissue and influence immune effector cells. Free radical damage to thyroid tissue is widely acknowledged to be a factor in the onset or exacerbation of AITD” – https://pmc.ncbi.nlm.nih.gov/articles/PMC9816468/

“iodine excess, due to extensive environmental iodine exposure in addition to poor monitoring, is currently a more frequent occurrence than iodine deficiency. Iodine excess is a precipitating environmental factor in the development of autoimmune thyroid disease. Excessive amounts of iodide have been linked to the development of autoimmune thyroiditis in humans and animals, while intrathyroidal depletion of iodine prevents disease in animal strains susceptible to severe thyroiditis. Although the mechanisms by which iodide induces thyroiditis are still unclear, several mechanisms have been proposed: (1) excess iodine induces the production of cytokines and chemokines that can recruit immunocompetent cells to the thyroid; (2) processing excess iodine in thyroid epithelial cells may result in elevated levels of oxidative stress, leading to harmful lipid oxidation and thyroid tissue injuries; and (3) iodine incorporation in the protein chain of thyroglobulin may augment the antigenicity of this molecule.” “The administration of iodine can significantly enhance and accelerate, in a dose-dependent manner, the incidence of AIT, its onset, the degree of lymphocytic infiltration and the severity of damage to thyroid follicular structures” – https://pmc.ncbi.nlm.nih.gov/articles/PMC4139880/

“Hemken, (1980) showed that iodine level in milk may vary over time, between 1965 and 1980, the iodine content of milk increased by 300 to 500 percent due largely to changes in cattle feeds” – https://journals.ekb.eg/article_75405_3e6bf8abe7f4940121a857cc158119eb.pdf

In 1980-1981: “In 378 samples of milk collected from farms and silos outside California, iodine… averaged 499 mcg/kg. [121.8 mcg/cup]” and “Historically, the concentration of iodine in milk has been considered to average around 40 mcg/kg. [9.8 mcg/cup] Before 1970, reported concentrations were generally less than 100 mcg/kg [24.4 mcg/cup] and the highest reported value was 165 mcg/kg. [40.3 mcg/cup] That the concentration of iodine in milk at the farm has increased in the last decade [the 1970’s] has been demonstrated indisputably in many parts of the world. The question we must address is whether the increase in milk iodine concentrations is a threat to the health of the milk-drinking population” – https://www.sciencedirect.com/science/article/pii/S0362028X23046318?ref=cra_js_challenge&fr=RR-1

“[Ray Peat] posited that thyroid antibodies should not be considered the cause of this form of hypothyroidism. Rather, he interpreted their presence as a sign that the body’s repair mechanisms are trying to heal the thyroid gland.” https://biochemnordic.com/the-truths-about-hashimotos/

Ray Peat on Hashimotos – https://www.youtube.com/watch?v=OVs-SlJnzs4

Seafood by iodine content: https://pub.mdpi-res.com/nutrients/nutrients-14-00195/article_deploy/html/images/nutrients-14-00195-g001.png?1641032405 Salmon, sardines, herring are all 30-35mcg per 4 oz according to another source.

“In a random trial in Wales some participants received 500 μg iodide in addition to their normal daily intake of 250 μg. Some of those receiving the additional iodine showed significantly elevated TSH levels compared to the placebo controls (Chow et al., 1991). Excessive intakes can cause an increase in thyrotoxicosis and Hashimoto’s disease (with autoantibodies against thyroid proteins”- https://ec.europa.eu/food/fs/sc/scf/out146_en.pdf [In that Welsh study looks like TSH went up 0.55 mU/I in 2 weeks, and up 0.59 mU/I by 4 weeks – https://pubmed.ncbi.nlm.nih.gov/2060151/ ]

“In a survey of 3,300 children aged 6-12 years from five continents, thyroid glands were twice as large in children with high dietary iodine intake (about 750 mcg per day), compared with children with more normal iodine intake. While the significance of that finding is not clear, it suggests the possibility of iodine-induced goiter.” “In one study, dietary restriction of iodine reversed hypothyroidism in twelve of twenty-two patients; seven of the patients with reversed hypothyroidism were re-fed iodine and became hypothyroid again (Anthony P Weetman, Autoimmune Diseases in Endocrinology, pp 50-51).” “In food and in the body, iodine is usually bound with protein compounds. The main iodine-containing compounds in the body are the thyroid hormones thyroxine (T4, four iodine atoms joined to tyrosine) and triiodothyronine (T3, three iodine atoms joined to tyrosine).” “Weston Price reports in primitive diets. In preliminary analyses, he found a range of 24-32 mcg [iodine] daily for the northern American Indians and 131-175 daily for the Inuit. Apparently the Inuit of the far north do not eat seaweed.” https://www.westonaprice.org/health-topics/modern-diseases/the-great-iodine-debate/#gsc.tab=0

Safe upper limit for Iodine in animal feed and how too much can cause heavy dairy consumers to get excessive iodine: https://www.efsa.europa.eu/en/efsajournal/pub/3100

Ray Peat on autoimmune diseases: “[Do high level of Thyroglobulin Antibodies and Thyroid Peroxidase (TPO) Antibodies show autoimmune thyroditis?] When TSH is too high for a long time, it causes inflammation in the gland, and the antibodies are in reaction to that. [Type 1 diabetic with TPO antibodies] Was your TSH tested? Usually the antibodies just mean that the thyroid gland is inflamed, and increased TSH can be responsible for that. T4 can suppress TSH protectively, but since intracellular glucose is needed for making T3, diabetes can interfere with that. I think some T3 is always appropriate with diabetes. [TSH was 3.9] I think the high TSH explains the antibodies, and a combination of T4 and T3 is usually all that’s needed; it usually takes a few months after suppressing TSH for the antibodies to decrease. Cortisol would be important to know, also estrogen and prolactin would be more informative than the common thyroid tests. [Autoimmune diets] Have you seen my website article on milk? It mentions some of the things behind gluten sensitivity. Hypothyroidism is one thing that commonly causes leaky gut, as well as leaky liver, muscles, heart, thyroid gland, etc. The immune system reacts to the leakiness, and although it might be an effect, rather than a cause, the presence of antibodies is sometimes said to show autoimmunity. [Test for cross-reactive foods] The presence of specific antibodies means that someone has been exposed to an antigen, but it doesn’t indicate that they will react badly to it.”

14 mcg iodine per ounce is typical for cheese (and an ounce is pretty close to equivalent to a cup of milk which has 85mcg iodine) – so that could be a good way to get calcium and fat soluble vitamins without so much iodine.

Go below 100 mcg to reverse thyroid disease according to Dr Christianson, for probably 3-9 months, then maintain under 200mcg after – https://www.youtube.com/watch?v=R085kZw3YBQ

Iodine sweet spot is 50-99 mcg = reversal of hashimotos. Under 50 = goitre. 100-200=low rate of hashimotos. Over that=problems. From: https://thyroidpharmacist.com/articles/iodine-hashimotos/

Iodine based dough conditioners used to be common, as of 2019 they are present in 20% of bread products. Seems like hamburger buns and hot dog buns are common culprits. And possibly bagels. When made with these conditioners, a bun has 530mcg iodine, one slice of white bread has 148mcg iodine. https://www.ars.usda.gov/ARSUSERFILES/80400535/DATA/IODINE/IODINE_DATABASE_RELEASE_3_PER_SERVING.PDF

Turns out that sea salt varies a lot in iodine content. Some is quite high. Morton’s sea salt is actually from the Great Salt Lake, which has 5x more iodine than the ocean. Great Salt Lake brine has 2.3-2.7 ppm iodine, not sure what that is in micrograms. Source: https://ugspub.nr.utah.gov/publications/water_resources_bulletins/wrb-17.pdf

Restaurants use sanitizer everywhere and one of the approved sanitizers is iodine-based. Schools/daycares also use sanitizers constantly, and of course healthcare facilities (So anyone who is in these facilities for a long time could be damaged by all that) – Apparently the typical foodservice sanitizer is diluted chlorine bleach, another common one is quat (quaternary ammonium chloride compounds). Quat causes birth defects: https://cen.acs.org/safety/consumer-safety/know-enough-safety-quat-disinfectants/98/i30 – Disinfectants obviously cause cell death, they kill the bacteria, so why don’t they kill your cells too?

My estimates of iodine intake in the US at various times: