- Improving Hypothyroidism|
- Diet Guidelines|
- Foods to Eat|
- Foods to Avoid|
- Iodine Deficiency|
- Assessing Iodine Levels|
- Bottom Line|
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.  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.” 
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.
- 78.3% of Hashimoto’s patients who were assigned a low-iodine diet became euthryoid (normal thyroid) in 3 months. 
- 53% of hypothryoid patients became euthryoid after 3 weeks of iodine restriction. When iodine was resumed, they became hypothyroid once more. 
- 33% of hypothyroid patients became euthyroid, and 63% decreased their TSH values by more than 50% and to less than 10 mU/L, solely from iodine restriction. 
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.      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:
- Organic food, which is free of chemical pesticides and herbicides. (Chemicals can negatively affect your thyroid gland.)
- Real, unprocessed foods, which are free of additives and chemical preservatives. This includes:
- Produce: Fresh fruits and vegetables, including fruit juices, applesauce, or dried fruit.
- Healthy fats: Cold-pressed vegetable oils like olive oil and coconut oil, and avocados.
- Grains, cereal products, and pastas without high-iodine ingredients, or iodate dough conditioners.
- Animal Protein: Free-range, grass-fed, or wild-caught, fresh meat, fish, and poultry, including egg whites.
- Nuts and Seeds: Unsalted nuts and unsalted nut butters, such as peanut butter.
- Herbs and Spices: Including black pepper.
- Non-iodized sea salt may be used as desired.
- Natural Sweeteners: Honey, maple syrup, or unsulphured molasses.
- Avoid any known food allergies, as these contribute to inflammation. Some people with thyroid conditions react to gluten, so a three-week gluten-free trial might be worthwhile.
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:
- Iodized salt, or foods that contain iodized salt: for example, commercial salad dressings or sauces.
- Dairy products—cheese, cream, yogurt, butter, ice cream, milk chocolate
- Egg yolks, whole eggs, and foods containing whole eggs
- Seafood—fish, shellfish, seaweed, kelp
- Foods that contain the additives carrageenan, agar-agar, or alginates
- Cured and corned foods—ham, lox, beef, sauerkraut
- Fresh, canned, or dried legumes and beans, such as kidney beans, cowpeas, lentils, and pinto beans.
- Bread products that contain iodate dough conditioners, such as muffins, bread, tortillas, and cakes.
- Soy products — soy sauce, soy milk, tofu
- Any supplements that contain high-iodine ingredients, especially seaweeds like nori, kelp, and dulse
- Blackstrap molasses
- Red Dye #3—ask your pharmacist whether your medications contain Red Dye #3, which contains iodine. Maraschino cherries and some candies also contain red dye #3.
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. 
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.  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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