Why Is Iodine Controversial?

Some integrative-health practitioners see the recent rise in thyroid-related diseases — including hypothyroidism and thyroid cancer — as evidence that we need more ­iodine than public health guidelines suggest.

“Many feel the current adult RDA of 150 mcg per day was provided as a baseline to prevent goiter and is not an appropriate level for ideal iodine balance to allow for its full range of benefits,” explains Malini Ghoshal, RPh, MS.

Some also argue that our increased exposure to the iodine-blocking effects of halogens (including chlorine) and halides (such as fluoride) may require us to consume dramatically more iodine in order to push out these blockers and free up iodine-receptor sites.

But an approach like this can pose dangers, especially to people with hyperthyroidism, hypothyroidism, or autoimmune thyroid conditions such as Graves’ disease.

“If you have a preexisting thyroid condition or have experienced iodine deficiency in the past, you may be more vulnerable to thyroid disorders … if you take in too much iodine,” explains Ghoshal. “This may happen even with small increases in iodine intake, but it’s particularly risky if you’re exposed to high levels of iodine for a long time or experience an iodine overdose.”

This increased vulnerability may be due to something called the Wolff-Chaikoff effect. “Basically, your thyroid has a safety switch,” explains Alan Christianson, NMD, author of The Thyroid Reset Diet, in a blog post. “If too much iodine comes in, rather than make lethal amounts of thyroid hormone, your thyroid shuts off. It is a great example of homeostasis and has been used … to slow the thyroid when it is overactive.”

For most people, the Wolff-Chaikoff effect reverses once iodine levels normalize, but for people with thyroid problems, it can be permanent.

Christianson recommends that people avoid iodine supplements, and he views universal iodization to prevent goiter as an overcorrection. He points to research that suggests universal salt iodization has increased hypothyroidism, hyperthyroidism, and autoimmune thyroiditis in susceptible populations.

“The paradox is that populations that run on the low side of iodine have the lowest rates of autoimmune thyroid disease,” he states.

“The benefits and the harms of iodine are a U-shaped curve,” adds April Lind, MD, a board-certified internal-medicine, pediatrics, and functional-medicine physician.. “If you have too little, it’s a problem; and if you have too much, it’s a problem.”