Low Iodine Diet: Improve Hypothyroidism

Research suggests that following a low-iodine diet may help reduce or resolve hypothyroid conditions.

Contrary to popular wisdom, science shows that a low-iodine diet can be beneficial for a significant number of hypothyroid patients. 

While some practitioners recommend iodine supplementation for thyroid patients, research suggests that a low-iodine diet may help reduce or resolve hypothyroid conditions. Research also shows that too much iodine can increase thyroid autoimmunity. Let’s take a closer look.

Reducing Iodine Improves Hypothyroidism for Some

Hitting the iodine sweet spot (neither too much or too little iodine) is important for thyroid health. 

You may know that iodized salt is a necessary public health measure to prevent goiter and other thyroid conditions. But supplemental dietary iodine has also been shown to increase the incidence of thyroid autoimmunity. [1] For example a systematic review and meta-analysis (the highest quality science) concluded that 

“…chronic exposure to excess iodine from water or poorly monitored salt intake are risk factors for hypothyroidism in free-living populations.” [2]

Additionally, a number of studies have shown that a low-iodine diet can resolve hypothyroidism for a significant portion of people.  Here are findings from three different studies.

The low-iodine diet didn’t help all the study participants, suggesting it may not help all thyroid patients. But with these promising results, a low-iodine diet is certainly worth a trial to help improve your thyroid health.

Low-Iodine Diet Guidelines

Reducing dietary iodine to improve your thyroid health is relatively simple. Let’s review what to include and what to avoid. 

Foods to Include on a Low-Iodine Diet

Decreasing the burden of inflammation in your body is helpful for managing almost any thyroid condition, as inflammation is associated with thyroid imbalances. [6] [7] [8] [9] [10] A low-quality diet is typically the single biggest source of inflammation for your body and can negatively impact your immune system. 

If you have a thyroid condition, creating an anti-inflammatory, low-iodine diet may be especially beneficial.

An anti-inflammatory, low-iodine diet includes:

What to Avoid on a Low-Iodine Diet

Whether you’re avoiding foods with iodine content for thyroid disease treatment, or because you want to see if your hypothyroidism will respond, here are some foods to avoid:

Be sure to check the ingredient lists on commercially prepared foods to make sure they are free of high-iodine ingredients.

What About Iodine Deficiency?

Iodine deficiency can cause health problems, such as repeated miscarriage, goiter, and increased risk of infant growth retardation and mortality. So you do want to make sure you are getting enough iodine.

The majority of Americans are getting enough iodine. That said, a recent review of the data concluded that iodine deficiency was emerging in some women of reproductive age. [11]

Some integrative health providers recommend supplementing iodine for thyroid patients, sometimes in very high doses. Their logic is that thyroid hormone is partly made of iodine, so supplementing will help your body synthesize more.

This logic vastly oversimplifies thyroid function. It’s important to consider the research, which strongly suggests that excess iodine can actually make thyroid symptoms worse. 

Assessing Your Iodine Levels

If you feel you may be iodine deficient, it’s important to proceed carefully.

There’s no well-validated method to assess your iodine levels. Of the available options, a 24-hour urinary iodine-creatinine ratio test is the best option. [12] A single urinary iodine collection can misrepresent your levels because iodine excretion can vary throughout the day.

An easier, more accessible way to assess your need for iodine would be to track your diet for one to two weeks with the app Chronometer. You can print out a report of the micronutrient content of your diet. If it looks like you aren’t getting enough dietary iodine, you can first increase your intake of iodine-rich foods, including seafood, iodized salt, dairy products, eggs, and soy products.  

If your doctor has clearly ruled out autoimmune hypothyroidism, and your 24-hour iodine test or micronutrient results still appear low, you can run a short experiment and use 1 milligram of iodine per day. Work with your health provider to track your TSH levels to see how you respond.

The Bottom Line

Contrary to popular wisdom, reducing dietary iodine intake with a low-iodine diet may lead to remission of hypothyroid disease for a significant number of patients. If you have been diagnosed with hypothyroidism, a low-iodine diet is worth a trial to see how you respond.

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