How a Low Iodine Diet Can Help Your Thyroid - Dr. Michael Ruscio, DC

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How a Low Iodine Diet Can Help Your Thyroid

Take Care of Your Thyroid Through Your Diet

Key Takeaways:

  • Too little or too much iodine intake can disrupt your thyroid function. 
  • Excess iodine consumption is linked to hypothyroidism, thyroid autoimmunity, and thyroid nodules. 
  • Decreasing your iodine consumption may improve hypothyroidism and Hashimoto’s thyroiditis. 
  • A low iodine diet includes plenty of fruits, vegetables, and iodine-free grains.
  • The low iodine diet eliminates iodized salt, kelp, dairy products, egg yolks, and seafood. 
  • Those who are at an increased risk for iodine deficiency and may not be good candidates for a low iodine diet include pregnant women, kids, and those consuming a vegan or vegetarian diet.

Iodine is an essential nutrient for optimal thyroid function, but current research suggests that a low iodine diet may actually be your ticket for boosting thyroid health. So what gives? Turns out, as it goes for many vital nutrients, balance is key — more is not always better.

Loading up on fresh fruits and vegetables, and skipping the iodized salt, kelp, egg yolks, and dairy products can help lower your iodine levels. And if your thyroid has been acting a bit sluggish, a reduction in iodine intake may be all it takes to get it back to normal. Many alternative practitioners are pushing for iodine supplementation, but, despite popular belief, higher levels of iodine are actually linked to increased rates of hypothyroidism and Hashimoto’s thyroiditis.

Though a low iodine diet is highly beneficial for the thyroid, you definitely don’t want to become deficient in this important nutrient, as it can also lead to thyroid disease. Those who are pregnant or following a vegan or vegetarian diet are already at an increased risk for iodine deficiency and may want to skip a low iodine diet or simply make sure they are consuming enough iodine-rich foods to meet the daily requirement. 

Read on to find out if you’re a good candidate for the low iodine diet, and how to make it work for you. 

Why Choose A Low Iodine Diet?

A low iodine diet seems to have very select benefits for your hormonal health, specifically on your thyroid gland. Having a healthy thyroid is incredibly important, as this small  butterfly-shaped gland regulates your digestion, weight, skin and hair health, and even your mood.

Adequate iodine intake can help prevent conditions like hypothyroidism and goiter. However, high iodine intake (which is much more common than low intake) can also increase your risk for thyroid disease [1, 2, 3].

If you have any of the following conditions, a low iodine diet is likely a good option for you:

  • Subclinical hypothyroidism (symptomatic with thyroid levels in the normal range) [4, 5, 6, 7]
  • Clinical hypothyroidism (thyroid levels outside the normal range) [4, 5, 6, 7]
  • Hashimoto’s thyroiditis
  • Thyroid cancer and undergoing radioactive iodine therapy [8, 9]

A low iodine diet appears to mostly benefit those with thyroid conditions, as researchers are still exploring the link between dietary iodine and other health concerns. However, there is ample research on the benefits of an iodine-restricted diet for thyroid health, and it shows significant benefit in improving, or even reversing (as in the case of hypothyroidism), the above conditions. 

Three separate studies showed that a low iodine diet positively affected thyroid-stimulating hormone (TSH) and thyroxine (T4) levels in a significant number of participants and reversed their hypothyroidism after following the protocol for 1-3 months [4, 5, 6].

Let’s further explore why reducing your iodine intake may be a good idea.

The Health Risks of Excess Iodine

Over-consumption of iodine, whether it be through iodine-rich foods or iodide supplements, is associated with thyroid disease. High iodine intake is linked to hypothyroidism, Hashimoto’s thyroiditis, and thyroid nodules [10, 11]. Excessive supplementation has also been associated with other thyroid diseases, like hyperthyroidism and papillary thyroid cancer [1].

While rare, true iodine toxicity can occur, most often after taking high doses of iodine supplements. Other signs that you may be overdoing it on this mineral include [1]:

  • Nausea and vomiting
  • Diarrhea
  • Abdominal pain
  • Mental confusion
  • Shock

If you develop any of these side effects after taking high-dose iodide supplements, seek medical attention immediately. 

If you are already deficient in iodine and up your iodine intake too quickly, you may be increasing your risk of developing autoimmune thyroid disease and goiter [11, 12, 13, 14]. Even cautious use of iodized salt has been shown to increase thyroid antibodies in young women [12].

However, we certainly aren’t recommending that you not treat or ignore an iodine deficiency. While an iodine deficiency is rare, if you truly have low levels of this nutrient we recommend working with your healthcare provider on ways to safely increase your iodine intake.

How To Follow A Low Iodine Diet

Consuming a low iodine diet is actually quite simple and focuses on eliminating iodine-rich foods. While the goal isn’t to completely eliminate iodine from your diet, many of us eat an excess amount of this mineral, mostly through iodized salt.

However, there are some surprising sources of iodine, such as baked goods that use iodate dough conditioner. Below is a list of foods both high and low in iodine that can help guide you during your low iodine diet [8].

Low Iodine FoodsHigh Iodine Foods
Non-iodized salt or sea saltIodized salt
Egg whitesKelp or dulse (and supplements that contain them)
Homemade bread with non-iodized salt and oil (vegetable oils other than soy) rather than butter or milkDairy products (milk, ice cream, cheese, yogurt, butter, milk chocolate)
Commercially baked bread without iodate dough conditioners, dairy, or eggsSeafood (fish, sushi, shellfish, kelp, seaweed)
Fresh fruits and vegetablesHerbal supplements
Frozen vegetablesFoods with these additives: carrageenan, agar-agar, alginate, nori
Grains or cereal products and pasta with low iodine ingredientsCommercial bakery products made with iodate dough conditioners
Fresh meatsFD&C red dye #3 (in maraschino cherries and artificial color in pink or red beverages)
Canned fruit (such as applesauce)Egg yolks, whole eggs, and foods with whole eggs
Natural unsalted nuts and nut butters (like unsalted peanut butter; you can add non-iodized sea salt)Blackstrap molasses (unsulfured molasses is ok)
Sodas, beer, wine, lemonade, fruit juicesSoy products (soy sauce, soy milk, tofu); these don’t contain iodine, but can interfere with radioactive iodine uptake in animals
Coffee or tea without milk or cream or soy-based creamer
Popcorn popped in vegetable oil or air popped, with non-iodized salt
Black pepper, fresh/dried herbs and spices
All vegetable oils (other than soy oil)
Augar, jam, jelly, honey, maple syrup
Matzo crackers, rice cakes

The Paleo diet is a great whole-foods diet that we frequently recommend for its numerous health benefits, including better metabolic and thyroid health. It’s a great low-iodine diet, as it restricts two of the major sources of iodine: iodized table salt and dairy. Just make sure to skip the eggs and seafood if you are also trying to restrict your iodine intake. 

Though they are included on the low-iodine food source list, try to steer clear of sugar, sodas, and gluten-containing foods that can disrupt thyroid function and really don’t offer any health benefits.

After restricting your iodine consumption, it may take 3-4 weeks (possibly up to 3 months) to see improvement in your thyroid function [4, 6]. Additionally, research shows that those who returned to healthy thyroid levels after starting a low iodine diet quickly became hypothyroid again after resuming normal iodine intake [6]. While more research is needed to define a clear timeline for how long an iodine-restricted diet is necessary to reverse thyroid dysfunction, it does appear that it is a long-term strategy for those with hypothyroidism or autoimmune thyroid disease.

Don’t Completely Cut Out Iodine

Even if you’re following a low iodine diet, it’s essential that you get enough iodine to keep your thyroid healthy, as too low of levels are also linked with thyroid disease. Remember, when it comes to iodine, it’s essential to balance (not eliminate) your intake.

The Recommended Dietary Allowance for adult male and female iodine intake is 150 micrograms/day, but as long as you’re in the 150-450 mcg range you should be good [15]. Food is probably the safest and best way to meet your daily iodine requirement, and following a balanced diet should give you adequate iodine levels [16].

Not sure if you’re getting enough iodine? Try using a food-tracking app like Chronometer to track your iodine intake. If you’re not meeting the daily requirement, we recommend cutting your non-iodized sea salt with iodine-rich, seaweed salt. You can also refer to the above table for more ideas on how to get iodine into your diet.

If you try the above method and are still worried about having too low of iodine intake, you can ask your healthcare provider for a 24-hour urinary iodine-creatinine ratio test. Most iodine tests have a large room for error, but research shows that this may be the most accurate option [17].

What If A Low Iodine Diet Doesn’t Work?

If you try restricting your iodine intake and see no improvements in your thyroid after a few months, it may be time to focus on the gut. Thyroid disease often stems from an unhealthy digestive tract and, if this is the case for you, iodine restriction alone may not quite cut it. 

A low-iodine Paleo diet can certainly help heal and lower inflammation in the gut by removing potentially inflammatory food triggers from the diet. However, if it doesn’t give you the results you need, you may need a more focused dietary approach to address any underlying dysfunction, like a gut bacteria imbalance. 

The low FODMAP diet is great for restoring the gut microbiota, and can be especially impactful if you are dealing with symptoms like gas, bloating, stool changes, and stomach pain along with thyroid disease. The FODMAP diet removes certain fermentable starches and sugars that can feed an unhealthy overgrowth of gut bacteria that’s contributing to thyroid dysfunction. 

For other ideas on how to help support your digestive tract, check out one of our many articles on gut health

When To Avoid A Low Iodine Diet

Though iodine deficiency is uncommon, a low iodine diet is definitely not indicated for everyone, including expecting mothers. Pregnancy increases your daily requirement for iodine, which is necessary for the baby’s health. Maternal iodine deficiency during pregnancy is associated with abnormal fetal development, endocrine abnormalities, and low IQ [18]. In children, low iodine levels may cause permanent disruption of their thyroid gland, so they are also poor candidates for a low iodine diet [19].

Low iodine intake is also associated with hyperthyroidism, or an overactive thyroid gland [10]. If you have been diagnosed with hyperthyroidism or Grave’s disease, it may be best to steer clear of a low iodine diet. 

If you’re following a vegan or vegetarian diet you may also want to avoid further restricting their iodine intake, as you’re already at an increased risk for iodine deficiency [20, 21]. If you’ve cut out iodized salt and also eat a lot of foods high in goitrogens, such as soy, broccoli, cauliflower, and Brussels sprouts, you are also subject to low iodine levels [18].

Goitrogens are compounds found in foods that block iodine from entering the thyroid gland, and, if eaten in high quantities, can cause thyroid dysfunction. However, boiling or steaming these foods stops the activity of these compounds, making them safe, even in large amounts.

Lastly, if you already have a healthy thyroid gland, with normal thyroid levels, there’s really no reason to start restricting your iodine intake. But if you’re already on a low-iodine diet, such as the Paleo diet, just make sure you’re meeting the daily iodine requirement. 

Remember, when it comes to iodine, it’s having a balanced intake that’s important. 

Making A Low Iodine Diet Work For You

Both too little and too much iodine intake can cause thyroid disease. However, iodine deficiency is uncommon and many people consume an excess amount of the mineral. If you have hypothyroidism, Hashimoto’s thyroiditis, or even thyroid nodules, a low iodine diet may help restore normal thyroid function. 

A low iodine diet removes foods that are abundant in this nutrient, including iodized salt, dairy, eggs, and kelp. The Paleo diet is a great low iodine diet to follow, just make sure you are still meeting the daily requirement for iodine intake. A deficiency of iodine can also have negative effects on your thyroid, so finding a happy medium is essential. 

Pregnant women and children should probably avoid a low iodine diet, as the risks of iodine deficiency in these populations are high. And if you’re already following a low-iodine diet, such as a vegan diet, be sure that you don’t overly restrict your intake. 

For help with getting your thyroid into tip-top shape, don’t hesitate to reach out to our functional health center You can also explore the relationship that our diet has on our metabolic health in my book, Healthy Gut, Healthy You.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.

➕ References
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