Is Your Iodine Supplement Safe?

redPlease also see: Why I Prescribe Iodine for Breast Pain, Ovarian Cysts, and PMS.

It is simply NOT safe to take the high-dose iodine promoted by some practitioners and websites. Megadoses of iodine cause acne, thyroid disease, and other disorders. (1)  

Why the confusion? Why does the most popular natural treatment FOR thyroid actually HARM thyroid?

In a recent study, up to 47% of people taking more than 1000mcg of iodine developed thyroid disease. (2)

Most cases of thyroid disease in Australia (and other developed countries) are autoimmune. This is critical to understand. Your thyroid condition is caused not by iodine deficiency, but by the attack of your immune system on your thyroid. Your doctor didn't mention this fact because it doesn't affect conventional treatment. But it does affect natural treatment. This fact makes it very tricky to use iodine because iodine worsens the underlying autoimmune problem. Iodine also directly reduces the ability of the thyroid gland to make thyroid hormone (by suppressing the TPO enzyme). 

The best natural way to treat autoimmune thyroid disease is to treat the immune system. You can read more about this approach in Lara's thyroid article. 

Why is mega-dose iodine such a popular natural treatment? In a word, wishful thinking. It a persuasive idea that something so simple could be the solution to something as complex as autoimmune thyroid disease. Many people do report feeling well on megadose iodine, but that is NOT from its benefit on thyroid. Iodine does other things. For example, it calms down the oestrogen receptor and relieves symptoms of oestrogen dominance. It is also a broad-spectrum antibiotic, and that may make someone feel better. But if an antibiotic is what is required, there are better natural options.

Iodine also directly supports brain and nerve tissue. Iodine changes the way that other hormones are metabolised. For example, iodine reduces the reactivity of the oestrogen receptor, and in this way can bring great relief to the symptoms of oestrogen dominance such as fibrocystic breast disease. These same benefits can be achieved with lower, safer doses of iodine. 

Many Australians are deficient in iodine and do require supplementation. A good, safe dose of iodine is 200mcg-1000mcg (0.2mg-1mg). This is a safe dose even for someone with autoimmune thyroid disease.

In contrast, one popular iodine supplement delivers 12,500mcg-50,000mcg (12.5mg-50mg) per tablet.  This is a dose that is 100x greater than the safe, effective dose outlined above. 

The negative effect of iodine on thyroid autoimmunity can be partially mitigated by selenium supplements, but it still doesn't make a megadose safe or okay.  (See the Thyroid article for more information).


(1) Gaby, Alan R. Megadose iodine: an idea whose time has gone. Townsend Letter, Dec, 2010 

(2) Sang Z et al. Exploration of the safe upper limit of iodine intake in euthyrroid Chinese adults: a randomized double-blind trial. Am J Clin Nutr. 2012. 95: 367-73. PMID: 22205314.

(3) Xue H. et al. Selenium upregulates CD4(+)CD25(+) regulatory T cells in iodine-induced autoimmune thyroiditis model of NOD.H-2(h4) mice. Endocr J. 2010;57(7):595-601. PMID: 20453397

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