Hashimoto’s thyroiditis, also known as chronic autoimmune thyroiditis, is one of the most common autoimmune conditions. In the United States, Hashimoto’s is the leading cause of hypothyroidism, or abnormally low function of the thyroid gland. Although It shares triggers with other autoimmune conditions, the thyroid’s specific nutrient needs and body-wide influences make Hashimoto’s a condition with unique nutrition considerations.

In this article, we’ll review Hashimoto’s and hypothyroidism, how symptoms can mimic several nutrient deficiencies, and why the nutrient density of foods matters. We'll also connect Hashimoto’s with the functioning of the digestive tract, why weight is not the most productive focus for managing the condition, and different diet options for support. Read on! 

What Is Hypothyroidism?

The thyroid is a butterfly-shaped gland in the throat responsible for making hormones your entire body needs. Two hormones, abbreviated T4 and T3, directly impact energy metabolism in the cardiovascular, nervous, musculoskeletal, reproductive, and gastrointestinal systems. Thyroid dysfunction can cause symptoms throughout your body, increase your risk of developing other conditions, and generally lower your quality of life. (Source, Source)

Hypothyroidism can be caused by genetic and environmental factors, including nutrient deficiencies, a viral or bacterial trigger, a side effect from some medications, and possibly exposure to harmful chemicals or metals. (Source, Source, Source)

What Is Hashimoto’s Thyroiditis?

Hypothyroidism is diagnosed when thyroid stimulating hormone (TSH), which is released by the pituitary gland to signal the thyroid to produce its hormones, is abnormally high, and T4 released by the thyroid is abnormally low. Subclinical hypothyroidism is diagnosed when TSH is abnormally high while T4 hormone levels are within the normal range. 

In Hashimoto’s, antibodies specific to the thyroid called thyroid peroxidase antibodies (TPO ab) and antithyroglobulin are present, with or without abnormal TSH and thyroid hormone levels. High TPO antibodies promote the gland’s destruction and lead to a decline in essential hormone production. (Source, Source, Source)

What Are the Symptoms of Hashimoto’s Thyroiditis?

Because the thyroid is involved in so many biological processes, decreased thyroid function can affect many parts of the body. Symptoms of Hashimoto’s may include fatigue, weight gain, lack of appetite, concentration problems, depression, constipation, dry skin, hair loss, slowed heart rate, cold intolerance, muscle pain, and menstrual irregularities. (Source, Source)

Thyroiditis also affects motility of the gastrointestinal tract — causing digested food to move through it more slowly — which can influence bacterial balance. Impaired motility may also increase cholesterol levels and affect blood sugar levels, bone health, and conversion of some food compounds into needed vitamins. Long-term changes in metabolic functioning from decreased thyroid function increase the risk of developing diabetes and heart diseases. (Source, Source) 

What Is the Treatment for Hashimoto’s Thyroiditis?

Levothyroxine is a synthetic form of T4 that is taken by mouth when the thyroid produces insufficient amounts. While it is usually recommended as a lifelong medication, there is some evidence that up to one-third of those on levothyroxine might not need to stay on it long-term, especially if they have been diagnosed with subclinical hypothyroidism. The evidence for this is not strong, however, and more studies are  needed. (Source)

Some people taking levothyroxine have normal TSH and T4 levels but still struggle with symptoms and decreased quality of life. One theory is that while levothyroxine can normalize TSH and T4 levels, not enough T4 produced this way is converted to T3, the active form needed by the body. Other possibilities include symptoms of nutrient deficiencies and gastrointestinal imbalances that commonly occur along with hypothyroidism. (Source)

Hashimoto’s Thyroiditis Diet: 6 Nutrition Principles

It may be possible to feel better with Hashimoto’s if you consider your diet as a form of medicine. In addition to taking prescribed medication when necessary, the following 6 nutrition principles can support your thyroid function, symptoms, and overall health, whether you have been diagnosed with Hashimoto’s, subclinical hypothyroidism, or hypothyroidism. (Source, Source)

Principle #1: Consider Nutrient Density 

Some micronutrient deficiencies can increase the risks of developing Hashimoto’s and are connected to worsened thyroid function. Correcting deficiencies with a nutrient dense diet can improve thyroid functioning and lessen symptoms associated with poor thyroid function.

Keep in mind, though, that some nutrients essential for thyroid health are needed in relatively small amounts. Excess of some, including selenium, iron, and zinc, can have toxic side effects. Consuming micronutrients through food, rather than dietary supplements, can be the safest way to get the proper amounts. If you are concerned about deficiency, a health care professional can help you determine your needed levels.

Selenium

Selenium concentrations are higher in the thyroid than in any other organ, and many of the thyroid’s proteins contain this critical micronutrient. It is a precursor to glutathione, the body's master antioxidant, which is shown to be lower in those with Hashimoto’s. 

• The recommended dietary allowance (RDA) is 55 mcg per day. 
• Some sources of selenium include:

• Brazil nuts (just one Brazil nut has ~70-90 mcg of selenium!)
• fish, including tuna, halibut, and sardines (amount varies)
• turkey (31 mcg/3 oz serving)
• mushrooms (20 mcg/gram)

(Source)

Iron

Iron activates thyroid peroxidase, a thyroid enzyme involved in production of T3 and T4. Thyroid peroxidase is a target of TPO antibodies in Hashimoto’s. A deficiency of iron could, therefore, impair thyroid hormone production.

• The RDA of iron is 18 mg daily for premenopausal women and 8 mg for men and postmenopausal women. 
• Some sources of iron include: 

• fortified cereals (amount varies)
• beans (8 mg /1 cup)
• lentils (6 mg/1 cup)
• oysters (1 mg/oyster)
• organ meats (6 mg/3 oz)
• spinach (~1 mg/cup)
• molasses (1 mg/oz)

(Source, Source, Source)

Zinc

A zinc deficiency can disturb T3 and T4 levels and increase thyroid antibodies. 

• The RDA of zinc is 8 mg per day for women and 11 mg for men. 
• Food sources of zinc include: 

• oysters (10 mg/oz)
• fortified cereal grains (amount varies) 
• pumpkin seeds (~2 mg/oz)
• beef (4 mg/3 oz)

(Source, Source)

Magnesium

Magnesium is needed for over 300 processes in the body, including energy and antioxidant production. Magnesium deficiency can increase the risk of Hashimoto’s, and be in higher demand due to oxidative stress in those with Hashimoto’s. 

• The RDA of magnesium is ~320 mg daily for women and 420 mg for men above the age of 31.
• Some sources of magnesium include: 

• pumpkin seeds (156 mg/oz)
• chia seeds (111 mg/oz)
• almonds (80 mg/oz)
• spinach (78 mg/half cup)
• fortified cereals (amount varies)
• potato (43 mg/3 oz)
• brown rice (42 mg/half cup)

(Source, Source, Source)

Vitamin D

Vitamin D deficiencies are common among those with autoimmune diseases, and Hashimoto’s is no exception. This vitamin regulates more than 200 genes necessary for healthy physiological functioning, including thyroid function. Since sunlight is our primary source of vitamin D, many people are seasonally deficient. Repleting vitamin D levels often requires supplementation to be effective, but you should check in with your health care provider on the right amount. 

• The RDA of vitamin D is 15 mcg (600 IU) daily. 
• Food sources include:

• cod liver oil (34 mcg/tablespoon)
• fatty fish (mackerel, salmon; 14 mcg/3 oz serving)
• mushrooms (9 mcg in a half cup, if exposed to UV light)
• fortified cow’s milk (3 mcg/cup)

(Source, Source, Source)

Protein

Protein needs vary individually. However, consuming an adequate amount can help support thyroid function. 

• The RDA of protein per day is based on your body weight. However, other health conditions and calculation adjustments can also influence protein recommendations.
• Sources of protein include: 

• meats (~7 g/oz)
• fish and seafood (~7 g/oz)
• eggs (7 g/egg)
• lentils (18 g/1 cup)
• nuts (~7 g/quarter cup)
• dairy products (8 g/1 cup milk)

(Source, Source)

B12

B12 deficiency can be more common in those with Hashimoto’s and is associated with increased TPO antibodies. 

• The RDA for B12 is 2.4 mcg for most people aged 14 and over, 2.6 mcg for pregnant women, and 2.8 mcg for breastfeeding women.
• Food sources of B12 include: 

• clams (6 mcg/oz)
• salmon (1 mcg/oz)
• dairy products (1 mcg/cup milk)
• lean beef (~1 mcg/oz)

(Source, Source)

Foods and Nutrients Best In Moderation

Iodine

Iodine is needed for synthesizing T3 and T4. Iodine deficiency is a leading cause of hypothyroidism in parts of the world where not enough is present in the food supply. However, where dietary iodine is usually sufficient, such as in the United States, excessive iodine intake can actually make hypothyroidism worse. (Source)

• Food sources of iodine include iodized table salt, kelp, and seaweed

(Source, Source, Source) 

Goitrogens

Goitrogens are food compounds that may affect hormone production or promote abnormal thyroid growth when consumed in excess. They are found in raw foods and are usually deactivated by cooking. 

• Goitrogenic foods include legumes, soy products, and cruciferous vegetables such as raw cabbage, cauliflower, and broccoli.

Saturated Fats

Saturated fats have been found to decrease thyroid function in animal studies and increase triglycerides (fat) in the blood in humans. Due to increased risk of heart disease and metabolic syndrome, saturated fats should be consumed in moderation as part of a balanced diet in those with Hashimoto’s and hypothyroidism. 

• Some sources of saturated fats to minimize include butter, lard, solid cooking oils, and processed foods with higher saturated fat content such as cheese, ice cream, and processed red meats. 

(Source)

Principle #2: Consume Enough

The thyroid sets the body’s basal metabolic rate — that is, the energy needed to maintain basic life functions such as breathing and heart rate — and makes sure that carbohydrates, fats, and proteins from food are made available for those energy needs. When your thyroid doesn’t produce enough of its hormones, your metabolic rate slows and fewer calories are needed to keep your body running. This change in metabolic rate is thought to be behind the weight gain common with hypothyroidism.

Losing weight is sometimes the main nutrition focus in managing Hashimoto’s. However, trying to lose weight by restricting the number of calories you take in may decrease the amount of T3 your thyroid gland produces, which may further slow your metabolism. Managing your weight with regular physical activity and a nutritious diet is more likely to help support your thyroid function and stabilize your metabolism. (Source)

Focusing on nutrient density and getting enough (not too little, not too much) can help you build a more solid relationship with your body and food. Mindful eating approaches can help you transform unconscious eating habits and connect to an inner sense of when enough is enough. (Source)

Principle #3: Honor Your Gut

Digestive health is often not addressed in relation to the thyroid. However, evidence shows the health of the digestive tract can affect thyroid function and that thyroid function influences gut function. This makes digestive health one of the most important factors to consider for healthy thyroid function.

For example, hypothyroidism is one of the most significant risk factors for small intestinal bacterial overgrowth (SIBO), a condition related to the imbalance of bacteria in the gut known as dysbiosis. This may be related to the thyroid’s role in stimulating gastric motility (the movement of food and bacteria through the digestive tract). 

Small intestinal bacterial overgrowth can also be related to intestinal permeability or “leaky gut.” Leaky gut interferes not only with nutrient absorption but with the self-regulation of the immune system. It is also more common in those with Hashimoto’s. (Source, Source, Source, Source)

Gastric acid in the stomach is essential for digesting food and absorbing nutrients. Impaired thyroid function may decrease the amount of stomach acid produced, and Hashimoto’s has been shown to be correlated with the presence of antibodies to the parietal cells that secrete gastric acid. (Source, Source)

Improved gut health is sometimes the first step to improving thyroid (and overall) health. A leaky gut protocol or evaluating bacterial balance with a functional medicine provider can help you get some answers and support. (Source, Source, Source)

Principle #4: Mind Your Symptom Triggers

As with other autoimmune conditions, dietary triggers are common in Hashimoto’s. Replacing gluten, dairy, or high FODMAP foods can help alleviate symptoms for some people, but may not be necessary for everyone with Hashimoto’s. Food symptom triggers are not always a lifelong problem, but removing any you might have can help your gut heal. (Source, Source)

If you are concerned about food sensitivity or intolerance, consider a 5R gut healing protocol or allergen-focused elimination diet to determine how food might affect your symptoms. 

Principle #5: Support Stable Blood Sugar

Hashimoto’s can affect not only energy metabolism from the foods you eat, but also your blood sugar regulation. Some people with Hashimoto’s have insulin resistance and above normal morning blood sugars, which increases the risk of developing diabetes. (Source)

These tips can help with blood sugar balance:

• Minimize high-sugar foods and beverages, including simple starches such as white rice, sweetened beverages, chips, and cookies.
• Consume high fiber foods with your meals, including whole vegetables, fruits, and tolerable whole grains and legumes.
• Include protein foods with each meal. Protein helps buffer the effect of starches and sugars in a meal. Some examples include meats, fish, eggs, and nuts.
• Eat regular meals, and try to limit “grazing” or snacking throughout the day (unless needed) or going more than 5 hours in between meals.
• Get regular physical activity that feels good for your body. Just 30 minutes of brisk walking daily can decrease your chances of getting diabetes by 30%.

(Source)

Principle #6: Enjoy an Anti-Inflammatory Path

No two people’s health needs are the same, even with Hashimoto’s. Your digestive health, nutrient needs, inflammation triggers, stress levels, and other lifestyle factors make up a unique health story. 

What is best for you depends on your changing needs, and the only rule is to find ways to enjoy the health-promoting foods you choose. Enjoyment can increase motivation and the long-term sustainability of an eating pattern, and can make all the difference between whether dietary improvements are a fad or a lifestyle change. 

Several studies have shown the benefits of various eating patterns to lower inflammation and improve Hashimoto’s symptoms. Here are 6 to explore: 

WellTheory’s nutrition practitioners are here to help guide you through the process of a nutrition protocol that is best for you. To learn more about any of these approaches, explore our various autoimmune diet resources and consider a membership for lifestyle change support.

Resources for More Information on Thyroid Health

American Thyroid Association

National Institute of Diabetes and Digestive and Kidney Diseases

The Bottom Line on Hashimoto’s Thyroiditis Diet

The thyroid is a sensitive gland with an essential role in virtually every body function. Autoimmune hypothyroidism, or Hashimoto’s, requires a diverse approach to rebalance and improve your symptoms, which may have different root causes. Central to these is the focus on the nutrition in your diet, which can provide vital micronutrients for thyroid function, help with healing and rebalancing the digestive tract, and lower oxidative stress and ongoing thyroid damage. Diet is not only a helping hand in managing Hashimoto's symptoms, but it is medicine that can be as essential as medication in supporting you for the long haul.