Iodine is a hot supplement these days. Many people and practitioners have come to value iodine’s therapeutic potential, especially for breast and uterine fibroids. Iodine is also vital to thyroid function, as it is a major cofactor and stimulator for the enzyme TPO. But for the person with Hashimoto’s, supplementing with iodine is like throwing gasoline onto a fire. Because iodine stimulates production of TPO, this in turn increases the levels of TPO antibodies dramatically, indicating an autoimmune flare-up.33 Some people develop symptoms of an overactive thyroid,34 while others will have no symptoms despite tests showing an elevated level of TPO antibodies. Therefore, I rigorously advise anyone with an autoimmune thyroid condition to avoid supplements containing iodine, as many thyroid supplements do.
This may seem like confusing advice to the person with hypothyroidism who as been told her condition is the result of an iodine deficiency. Although iodine deficiency is the most common cause of hypothyroidism for most of the world’s population,35 in the United States and other westernized countries, Hashimoto’s accounts for the majority of cases of hypothyroidism.36 Also, studies show that when iodine is used to correct iodine deficiency in countries such as China, Turkey, and Sri Lanka,37 38 the rates of autoimmune thyroid disease increase.
Also, when iodine is added to table salt in some parts of the world, the rates of autoimmune thyroid disease again increase.39 Iodine supplementation isn’t causing Hashimoto’s per se, but it does seem to be a triggering factor.40 Some popular books on iodine therapy recommend supplementing with large doses of iodine to quench symptoms of Hashimoto’s. That’s because taking mega-doses of iodine will shut down the production of the TPO and inhibit thyroid hormone formation. As a result, the thyroid becomes less active, suppressing hyperthyroid symptoms. If you are considering supplementing with iodine but your symptoms strongly suggest Hashimoto’s, be tested several times to rule out an autoimmune thyroid condition. An autoimmune condition can fluctuate, and negative tests are not always definitive. In addition to a gluten-free diet and supporting overall health, which is discussed in later chapters, avoiding iodine supplements is another strategy for preserving thyroid tissue.