Hashimoto’s and Iodine: Good Idea or Bad?


Having the right amount of iodine is important for thyroid hormone production. And too little is the most common cause of hypothyroid problems worldwide. Some people think that this means, logically, iodine supplementation would be a good idea for Hashimoto’s patients. It turns out, these people are very wrong.

According to Dr. Datis Kharrazian, DC, who I have been a student of for many years, there is compelling evidence for avoiding iodine if you have Hashimoto’s. Much of the information below comes from his course, Mastering the Thyroid. In addition, check out his comment on his blog here.

Iodine Stimulates TPO (thyroid peroxidase) and Increases Immune Attack 

In the body iodine is a major cofactor and stimulator for TPO. A cofactor is something (usually a vitamin, mineral, enzyme or nutrient) that is used to build something else inside the body. When you have Hashimoto’s, TPO is under attack by your immune system. Increased iodine, especially as a supplement, increases the immune attack on the thyroid.

Graves Disease and Iodine: A Really Bad Idea 

The most extreme example of this is called Jod-Basedow Phenomenon, and it is caused by taking iodine. This occurs when people who are iodine-deficient also have high levels of thyroid antibodies. When they take this supplement, their immune system goes nuts. If you have Graves disease caused by autoimmune disease and you take iodine, you could soon be in a world of hurt.

Hashimoto’s and Iodine: None Can Actually Improve Symptoms

This also holds true for patients with Hashimoto’s. Reports have shown that too much iodine causes hypothyroidism in Hashimoto’s thyroiditis. A study from the Yonsei Medical Journal published in 2003 looked at how not taking this supplement affected patients with Hashimoto’s.

Here’s what they found: “….78.3% of patients with hypothyroidism due to Hashimoto’s thyroiditis regained a euthyroid state (meaning a normal thyroid state) with iodine restriction alone. Both a low initial serum TSH and a high initial urinary iodine concentration can be predictable factors for a recovery from hypothyroidism due to Hashimoto’s thyroiditis after restricting iodine intake.”

In other words, more than 3/4 of the patients returned to a normal thyroid state by just lowering the amount of iodine they took in.

Several Studies Worldwide Show Increased Iodine Equals Increased Autoimmune Thyroiditis

There are several studies with large numbers of people that have shown a direct link between increased iodine and autoimmune thyroid disease. Here are a few:

A study in China looked at 3,018 people and found that “…more than adequate or excessive iodine intake may lead to hypothyroidism and autoimmune thyroiditis.”

In Sri Lanka researchers kept track of the effects of using iodine on thyroid function and they charted their findings for 3 years. This was the first study of its kind. It showed the changes in autoimmune markers as the study went on and showed the increases in autoimmune disease in these people.

In Turkey a study looked at 1,733 adolescents and found that the elimination of iodine deficiency in the Eastern Black Sea region was also followed by an increase in autoimmune thyroiditis and thyroid dysfunction.

Bottom Line

Practitioners and health coaches who tell Hashimoto’s patients to take iodine may be causing a more aggressive autoimmune attack on thyroid tissue. And as many of you may know, lots of people who have Hashimoto’s don’t know that they have it because no one has tested for it even though they have signs and symptoms. This means that ruling out Hashimoto’s is extremely important before taking iodine.

If you have Hashimoto’s you should be cautious about using iodine. 



Surks M., Sievert R., Drugs and thyroid function, NEJM, 1995; 333(25):1688

Yoon SJ, Choit SR, Kim DM, et al. The effect of iodine restriction on thyroid functions in patients with hypothyroidism due to Hashimoto’s thyroiditis. Yonsei Med J. 2003 Apr 30;44(2):227-35.

Eur J Endocrinol. 2011 Jun;164(6):943-50. doi: 10.1530/EJE-10-1041. Epub 2011 Mar 28.

More than adequate iodine intake may increase subclinical hypothyroidism and autoimmune thyroiditis: a cross-sectional study based on two Chinese communities with different iodine intake levels.

Effect of iodine intake on thyroid disease diseases in China, NEJM, 2006, Jun 29;354(17);2783-93

Evolution of thyroid autoimmunity during iodine prophylaxis – the Sri Lankan experience. Eur J Endocrinology, 2003, Aug;149(2):103-10

High prevalence of thyroid dysfunction and autoimmune thyroiditis in adolescents after elimination of iodine deficiency in the Eastern Black Sea Region of Turkey. Thyroid, 2006 Dec;16(12):1265-71








About the Author Marc Ryan

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