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  • Writer's pictureEmily Lipinski

Is Iodine Helpful or Harmful for the Thyroid Gland?

As long as I can remember, iodine has been a key component of thyroid supplement formulas. It has been 6 years since I was finally diagnosed with hypothyroidism, however it has been about 9 years since I started experiencing symptoms of low thyroid function. And, like many other pro-active woman out there, once I had a feeling my thyroid was low, I went out to the natural food store and selected a thyroid supplement. Although there were many different companies selling “thyroid boosting formulas” they all had one ingredient in common: iodine.

First things first: What is iodine and why is it associated with helping the thyroid?

Iodine is a chemical element found in saltwater, some rocks and seaweed. Today, a brine (seasalt and water) is the primary source of iodine extraction. Iodine, not only a crucial nutrient for the thyroid gland, is used in medicine, dyes, colourants, photography and even used in animal feed!

Ok but back to the thyroid- Iodine is essential for the production of thyroid hormones. T3 and T4, the primary thyroid hormones, are primarily comprised of iodine! When your body doesn’t have enough iodine, it leads to iodine deficiency, which can cause an enlarged thyroid gland and a reduction of thyroid hormones.

So wouldn’t it make sense for everyone to take more iodine or iodine rich foods?

It’s not that simple. Iodine is known as a “narrow therapeutic index nutrient” meaning that too little iodine can cause hypothyroidism but too much iodine may also cause hypothyroidism. Although iodine deficiency has been linked to hypothyroidism, iodine excess has also been linked to autoimmune thyroid disease (Hashimoto’s). Additionally, if someone has elevated thyroid antibodies, adding in excess iodine into the diet can significantly increase antibodies.

My own TPO antibodies jumped from 300 to 470 when I first began uses higher doses of iodine in my supplements.

In fact, taking a high dose of iodine may not only aggravate Hashimoto’s but also increase thyroid cell destruction. The American Thyroid Association cautions against using doses of more than 500 mcg per day noted that doses above 1100 mcg may cause thyroid dysfunction.

Although these warnings are for the overall population, studies have found that people with Hashimoto’s may be sensitive to even smaller doses. That being said, some people may actually need higher doses of iodine to improve their thyroid function. Some well regarded functional medicine practitioners have used doses anywhere from 4mg to 12mg (4000mcg-12000mcg) to improve and regulate thyroid function in their patients.

The controversy arises with the fact that in 2007 the World Health Organization estimated that over 30% of the world’s population (2 billion people) has insufficient iodine intake. Furthermore, individuals who avoid iodized salt or follow to a salt-restricted diet may become iodine deficient. Vegetarians and vegans are also at risk of developing iodine deficiency, especially if they eat food grown in low iodine soil.

After I first introduce iodine into my diet and reacted poorly, I discontinued iodine supplementation. Once my antibody levels significantly decreased and I was ready to try using iodine again. I have now successfully added iodine in small doses into my diet without raising my antibody levels- but dosage, timing and monitoring is important!

So, what’s the bottom line? I recommend three important steps prior to supplementing with iodine:

1. Test your TPO antibodies. If they are elevated, restricting iodine in your diet for a few months, reducing stress and supporting your thyroid by other means (herbs, addressing “leaky gut” etc) can help to reduce your antibodies. Once your antibodies have significantly reduced, consider iodine.

2. Once you are ready to consider adding iodine into your diet and/or supplement regimen, test your urinary levels of iodine before adding iodine into your routine. If your levels are adequate or elevated, you could do more harm than good.

3. Ensure you are working with a good Naturopathic Doctor or Functional Medicine Doctor to monitor your thyroid hormone levels once using iodine.

What’s your experience with iodine? I would love to hear from you!

Leave your comments below.

Dr. Emily

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