McCall McPhersonFounder, Modern Thyroid Clinic.

#onthisday a little TIKTOK memory that I think is worth repeating

26 Jun 2026 · 1 min

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1:10

McCall McPherson explains how excess iodine can damage gut bacteria's ability to produce butyrate, an anti-inflammatory compound, leading to increased intestinal permeability and worsening Hashimoto's disease. High iodine supplementation raises thyroid antibodies and triggers flares even in people who aren't deficient.

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What if iodine is actually worsening your gut function and your autoimmunity and Hashimoto's? So obviously this is very, very controversial, but let's talk about the science. So too much iodine can actually reduce butyrate, which is an anti-inflammatory bacterial byproduct in our gut. And with lower levels of butyrate, guess what happens? We have increased gut permeability, which is directly correlated to autoimmunity and inflammation. So you've probably heard that increased levels of iodine can trigger Hashimoto's. You've also probably heard, oh my gosh, take a bunch of iodine to solve your thyroid problems. I fall into the first camp. Most of us actually are not iodine deficient anymore, and we have plenty of access to iodine. And when we begin to supplement in excess, especially, it can actually trigger a Hashimoto's flare and worsen antibodies. This study is a perfect explanation as to one of the mechanisms of how that actually happens. And this has been proven in both mice and humans. So I'll post the, the PMID link below, and you can find out more if you like.