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Foods to Avoid for Hyperthyroidism (and Foods to Enjoy)

Written by Dr. Michael Ruscio, DC on September 20, 2022

Written by Dr. Michael Ruscio, DC on September 20, 2022 — Reviewed by Dr. Hannah Hamlin

Diving Into the Research on the Best Foods to Help with Hyperthyroidism

• Forms and Symptoms of Hyperthyroid|
• Nutrient Density|
• Paleo Diet|
• Should You Limit High Iodine Foods|
• Eating for Thyroid Health|

Have you been diagnosed with hyperthyroidism and now you’re wondering if there are any dietary interventions that may improve your symptoms? You may have seen suggestions to avoid iodine-rich foods like meat, seafood, and eggs, but do you really need to remove all of these nutrient-dense foods? 

While there is very little research into diets for hyperthyroidism and/or Graves’ disease, we do have a large body of research on how diet can influence autoimmune diseases. Since Graves’ disease (an autoimmune condition) is the most common cause of hyperthyroidism, dietary changes that improve autoimmunity are likely to be beneficial.

So which foods may worsen the autoimmunity and inflammation behind your hyperthyroidism? And beyond avoiding foods, what should you be eating to support your thyroid function and feel your best? Let’s dive in. 

Common Forms & Symptoms of Hyperthyroidism

Hyperthyroidism (sometimes called overactive thyroid) is when there is too much thyroid hormone in the body. It occurs in about 1.2% of the population in the United States. The most common cause of hyperthyroidism is Graves’ disease, which comprises 60-80% of all cases [1]. It tends to occur in younger people, and it is an autoimmune disease. The second most common form of hyperthyroidism is toxic multinodular goiter which we see most often in older people [1]. 

Some common symptoms of Graves disease and hyperthyroidism are [1]:

• Heat intolerance
• Sweating
• Fatigue
• Heart palpitations and/or fluttering
• Tremors
• Insomnia
• Anxiety or nervousness
• Muscle Weakness
• Eye symptoms such as lid swelling, pain, redness, and double vision
• Weight loss

Graves disease is caused by autoimmune dysfunction and most often diagnosed first with a blood test to assess the serum levels of TSH- receptor antibodies. An endocrinologist may also do a thyroid scan and radioactive iodine uptake test [1, 2]. 

Foods to Avoid for Hyperthyroidism

If you’ve been diagnosed with hyperthyroidism, it’s important to avoid foods that may trigger inflammation and an autoimmune response. While these may vary from person to person, certain foods are inflammatory across the board. These include things like processed foods, refined carbohydrates, and sugar. 

Beyond these more obvious inflammatory foods, you may be sensitive to certain healthier foods, like gluten or other grains, dairy products, legumes, or eggs. 

If you already know that you feel unwell after eating certain kinds of foods, it’s probably best to avoid them. If you’re not sure, we recommend following an elimination diet plan to determine which foods seem to trigger your symptoms. 

Beyond individual triggers, what should  you do about foods that are high in iodine? Let’s explore this question further. 

Should You Limit Foods High in Iodine?

One of the most common dietary recommendations you will find for hyperthyroidism is to avoid iodine because having too much iodine has been associated with thyroid disease [3]. However, the most important role of iodine in the body is the production of thyroid hormones [4]. So, we want to be careful when recommending the avoidance of iodine-rich foods. Let’s look at what the research shows us about iodine and thyroid dysfunction. 

Excessive iodine intake can induce hyperthyroidism [2], so avoiding foods high in iodine may be helpful for some people [5, 6]. 

Interestingly though, studies show that subclinical and diagnosed hyperthyroidism were more likely to occur in areas with too little iodine than in those with enough or too much iodine. At the same time, thyroid stimulating hormone (TSH) was higher (hyperthyroid) with too much iodine and lower with too little iodine [3].

What this really means is that you want to maintain healthy levels of iodine, not completely avoid iodine altogether. Both too little or too much iodine can lead to thyroid problems. The Recommended Dietary Allowance for adult male and female iodine intake is 150 micrograms/day [7].It is important to remember that iodine is a trace element, essential to our health and metabolism [4, 8]. In fact, the most important role of iodine in the body is the production of thyroid hormone [4].

With all of that in mind, if high iodine is contributing to your hyperthyroidism, you may want to avoid eating large amounts of foods high in iodine such as [9, 10]: 

• Iodized salt
• Grains, cereals, and some breads  
• Seafood and shellfish
• Seaweed and kelp
• Beef 
• Poultry and egg yolks
• Dairy products

Please remember that iodine deficiency is a serious health risk [3, 11, 12, 13, 14, 15]. Even with hyperthyroidism, it is important to make sure you still get enough iodine when following a low-iodine diet  [16, 17]

Additionally, many of the foods on this list are very nutrient dense and, as noted earlier, nutrient density is extremely important in maintaining good thyroid levels and general health. 

If you are receiving radioactive iodine therapy for the treatment of hyperthyroidism or thyroid cancer [18], you may be told to avoid foods containing iodine because minimizing iodine intake may improve the effectiveness of radioactive iodine therapy [9, 10]. Of course, this is best to discuss with your oncologist.

What About Cruciferous Vegetables?

You may have heard that you need to avoid cruciferous vegetables such as broccoli, cabbage, cauliflower, and brussels sprouts if you have a thyroid condition. This is because goitrogens inhibit the uptake of iodine needed for the thyroid gland to produce thyroid hormone. However, you usually do not need to avoid eating goitrogens if you have hyperthyroidism unless you have a goiter [6, 8]. In fact, because these vegetables inhibit the uptake of iodine, they may be a good addition to your diet if your levels of iodine are too high. 

Foods to Enjoy with Hyperthyroidism 

Eating a nutrient-dense diet has been shown to be helpful for autoimmune thyroid disorders [19]. It has also been found that an energy-dense diet (higher calorie diet) may also be helpful, as high thyroid levels increase the body’s energy needs by 50-60% [20]. 

That same paper also noted the need to maintain healthy levels of calcium, phosphorus, and vitamin D, indicating that a higher calorie diet should also be a nutrient-dense one.

Maintaining healthy levels of micronutrients such as selenium, vitamin D, iodine, calcium, and magnesium helps to maintain healthy thyroid function.

Let’s take a look at each nutrient and what foods you can enjoy to help maintain good nutrient levels [21].

Selenium

Selenium supplementation has been shown to improve Graves’ disease in the short term [22]. It also has antioxidant and anti-inflammatory effects [21]. Foods high in selenium are brazil nuts, meat, liver, fish, shellfish, and spinach.

Vitamin D

Graves’ disease and other autoimmune disorders are associated with vitamin D deficiency [23]. A great way for your body to produce more Vitamin D is to get 15-20 minutes out in natural sunlight each day. Some foods that can boost Vitamin D levels are fish oil, fatty fish, and chicken eggs.

Iodine

Maintaining normal levels of iodine in the diet may be helpful for Graves’ disease/hyperthyroidism because having too little or too much iodine has been associated with thyroid disease [3]. Some foods high in iodine are iodized salt, plum, sea fish, iodized milk, dairy products, and chicken eggs.

Iron

Iron deficiency impairs thyroid function and proper iron levels have been found to be important for maintaining thyroid health and reducing autoimmune thyroid symptoms [19]. Foods that can improve iron levels are meat, animal offal (ex.: liver), pumpkin seeds, cocoa and bitter chocolate, sardines, and seafood.

Calcium, Magnesium, and Potassium

Hyperthyroidism increases the risk of osteoporosis [24], so a diet rich in nutrients involved in maintaining bone health such as these three and Vitamin D as we discussed before, may help to reduce the negative effects of elevated thyroid hormone levels [25]. 

Some good sources of magnesium are nuts, seeds, and leafy greens. To increase potassium you can add in banana, avocado, broccoli and even coconut water. Foods that you might want to add in for some potassium. For calcium you do not have to rely only on dairy, some other sources are broccoli, rhubarb, nuts and seeds, and sardines.

Focus on Nutrient Density First

Because a good mix of many meats, vegetables, seafoods, nuts, and seeds are important in thyroid health, focusing on eating a nutrient-dense diet is probably the best dietary intervention for thyroid support and wellness rather than focusing on avoiding a few specific foods for hyperthyroidism. 

The Paleo Diet for Nutrient Density

There are quite a few options for eating a nutrient-dense diet, but I often start people with a Paleo diet because it strikes a balance of not being too overly restrictive, while still removing foods that are commonly inflammatory that may contribute to autoimmune disorders.

Because Graves’ disease is the most common form of hyperthyroidism and that is an autoimmune condition, this low-inflammatory, nutrient-dense diet is a great place to start. 

In fact, one interesting case study found that an ancestral diet (Paleo diet) along with some lifestyle modifications such as yoga reversed Graves’ disease in a 34-year-old patient [26]. This mirrors the significant improvements we often see with our patients when we put them on a Paleo diet.

A Paleo diet focuses on filling most of your plate with vegetables, moderate protein, healthy fats, and some nuts and seeds. It removes the most common inflammatory foods such as gluten and other grains (cereals, breads, whole grains), legumes (beans), dairy products, and soy milk and other soy products (in fact, soy products can interfere with thyroid function) [27]).

Additionally, some people with hyperthyroidism also have celiac disease [1]. A Paleo diet removes gluten, but remember that not everyone with hyperthyroid needs to be gluten-free. If you don’t have celiac disease and are not sure how gluten affects you, try avoiding it for a month on the Paleo diet, and then reintroducing it to monitor how you feel.

A Paleo diet includes many foods that contain some of the nutrients needed for healthy thyroid function, such as brazil nuts that are rich in selenium, and animal products to maintain healthy iron levels. It is also anti-inflammatory, which is helpful for autoimmune conditions.

When looking at all of your options, it is helpful to know that one observational study also found that vegan, lacto-ovo vegetarian, and pescatarian diets all reduced the risk of developing Graves’ disease [28]. 

The most important thing, whichever dietary framework you choose to follow, is to avoid foods that trigger inflammation and focus on foods that are nutrient-dense. 

Putting it All Together: Eating for Thyroid Health

While an internet search on diet and hyperthyroidism may lead you to recommendations to avoid iodine-rich foods, a balanced look tells us that a nutrient-dense diet that supports healthy immune system function is best for maintaining healthy thyroid function. 

Eating a Paleo diet moderate in iodine-rich foods is a great option and will support healthy levels of nutrients that are often found to be lacking in thyroid dysfunction. If your doctor has found your iodine levels to be too high or you are undergoing radioactive iodine therapy, you may then want to limit Paleo foods high in iodine. 

Try a Paleo diet, or a similar anti-inflammatory diet, for a month and see if your symptoms improve.

If you are unsure if you have hyperthyroidism and want to work with a doctor to figure out what is causing your symptoms, you can become a patient at the Ruscio Institute for Functional Healthcare and we would be happy to help 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.