Hyperthyroidism Diet: Foods to Eat and Avoid

The thyroid is a small gland that secretes thyroid hormones which play an immense role in metabolism, protein synthesis, and growth. Hyperthyroidism is the condition of having an overactive thyroid — typically affecting 20 to 40 years old.

When the gland over-activates and produces too much thyroid hormone, it can cause health problems in metabolism, bone health, and nervous, reproductive, and cardiovascular systems. In this article, you'll learn how to eat a healthy and balanced diet to maintain health in hyperthyroidism.

Thyroid hormones and functions

The thyroid gland secretes the hormones Thyroxine (T4) and triiodothyronine (T3) to the bloodstream. These hormones go to cells and control how your body uses energy. However, too much of thyroid hormones speed up metabolism and affect the entire body, including:

Cardiovascular system. Thyroid hormones help regulate cardiac output (the amount of blood your heart pumps in a minute), heart rate, and strength. Irregular and rapid heartbeat is only one symptom of hyperthyroidism.

Digestive system. The thyroid helps modulate bowel movements. Hyperthyroidism may increase bowel movement resulting in diarrhea.

Reproductive system. Hyperthyroidism negatively impacts the reproductive system, especially in women. An imbalance in thyroid hormone levels may result in irregular menstrual cycles and fertility problems.

Bone health. The thyroid hormone is one of the determinants of bone synthesis. Too much thyroid hormone increases the rate of bone loss resulting in weaker bones or bone diseases such as osteoporosis.

Nervous system. In fetal development, thyroid hormone functions in the brain and nervous system develop. Thyroid problems may cause numbness, tingling, anxiety, nervousness, and irritability.

What causes hyperthyroidism

There are several causes of hyperthyroidism:

• Graves' disease, an autoimmune thyroid disorder, is the most common cause.
• Nodules in the thyroid gland.
• Thyroid gland inflammation is called thyroiditis.
• Excess iodine consumption. Iodine is essential for producing thyroid hormone, but too many results in increased thyroid hormones.
• Thyroid medicine. If people with hypothyroidism (underactive thyroid) take too much thyroid medicine, their thyroid may get overactive.

Who’s at risk for hyperthyroidism?

Certain conditions increase the risk of hyperthyroidism:

• Having a family member with hyperthyroidism.
• Being female.
• Being older than 60.
• Excess iodine intake or use of medication contains iodine.
  
• Having had goiter (enlarged thyroid) or thyroid surgery.
• Having pernicious anemia — a condition that occurs when the body lacks vitamin B12.

Common symptoms of hyperthyroidism

Thyroid hormones affect your heart, brain, gut, reproductive organs, and bones. Too much may cause symptoms, including:

• weight loss (despite having no issues with appetite and nutrition);
• fatigue;
• muscle weakness;
• nervousness or irritability;
• mood swings;
• abnormal bowel movements;
• swollen thyroid gland;
• fertility problems;
• irregular and rapid heartbeat;
• Goiter.

Diagnosis and Treatment of Hyperthyroidism

If you suspect having hyperthyroidism, schedule an appointment with your physician. Your doctor can diagnose the condition easily with a blood test for hormones, antibodies, and thyroid scans.

Medication, radioiodine therapy, and thyroid surgery are common treatments. Your physician and/or endocrinologist will choose the appropriate course of action based on your age, hyperthyroidism type, other health problems, and any allergies.

Nutrition for managing hyperthyroidism

There are no specific foods, diets, or supplements to treat thyroid diseases. However, sufficient levels of the micronutrients iron, selenium, iodine, and zinc are crucial for maintaining proper thyroid health. That's why it is important to choose healthier foods to match your nutritional needs.

The National Health Service recommends:

• Eating five portions of fruit and vegetables daily.
• Eating high-fiber foods — whole grains, beans, legumes, fruit, and vegetables.
• Choosing unsaturated fats over saturated and trans fat.
• Staying hydrated.
• Consuming dairy products.
• Avoiding foods with added sugars.
• Eating antioxidant-rich foods.
• Eating enough protein — meats, eggs, beans, legumes.
• Eating healthy fats — unsaturated fats, nuts.

Overall, eating a healthy and balanced diet provides your body with the nutrients it needs. However, dietary supplements can be used in cases of poor nutrition or nutrient deficiencies. Consult with your doctor before taking supplements to avoid negative effects on thyroid function.

The best foods for hyperthyroidism

Calcium, phosphorus, and vitamin D

Hyperthyroidism may cause weaker bones and osteoporosis. Calcium, phosphorus, and vitamin D are essential nutrients for bone health. Therefore, people with hyperthyroidism should eat foods rich in:

Calcium: dairy products, green leafy vegetables.

Phosphorus: dairy products, meat, seafood, legumes, and nuts.

Vitamin D is found in oily fish and egg yolk in limited amounts. Sun is a major source of vitamin D.

Selenium

Selenium is found in the thyroid gland. It maintains thyroid hormone synthesis. In some cases, selenium supplementation is used to treat mild thyroid eye diseases. More research is needed to determine the effectiveness of selenium supplementation in preventing or curing thyroid diseases.

Doctors recommend eating foods rich in selenium, including nuts (especially Brazil nuts), fish, shellfish, white meats, lentils, and beans. Selenium supplementation shouldn't be taken without doctor approval since excess amounts of selenium may cause health problems such as nausea, diarrhea, fatigue, and irritability.

Foods rich in antioxidants

Graves' disease, an autoimmune thyroid disorder, is the most common cause of hyperthyroidism. With Graves' disease, the immune system makes the antibodies that stimulate the thyroid cells. As a result, thyroid hormone production increases.

Antioxidant foods help modulate the immune system. Thus, an increased intake of colorful fruits and vegetables — orange, red, yellow, and green are recommended.

Quality protein

Muscle problems and weight loss as a result of increased metabolic rate are common symptoms of hyperthyroidism. Eating high-quality protein in adequate amounts is crucial to maintaining muscle mass and function. Protein sources include meat, egg, dairy products, lentils, and beans.

Cruciferous vegetables

In theory, cruciferous vegetables such as kale, cauliflower, and turnips are rich in compounds that inhibit iodine usage of the thyroid resulting in lower thyroid hormone production. However, there is no scientific data specifying the ideal amount of cruciferous vegetables needed for decreasing thyroid hormone production.

Foods to limit with Hyperthyroidism

Iodine-rich foods

Iodine is needed for synthesizing thyroid hormones. Our bodies can not produce iodine, so it must be supplemented by foods.

In some cases, excess iodine intake results in increased thyroid hormone synthesis. Thus, eating foods high in iodine may awaken or worsen the symptoms in people with hyperthyroidism. Foods high in iodine include:

• Seaweeds include kelp (brown seaweed), dulse, and nori. A gram of seaweed contains around 2 mg of iodine — when scientists state that 1.1 mg/day is a safe upper limit.
• Seafood — sea fish and shellfish.
• Saltwater fish.
• Cow's milk and dairy products.
• Meat.
• Eggs.
• Iodine-fortified foods — some cereals, vegan milk, salt. According to UNICEF, almost 90% of the world's population consumes iodized salt. One teaspoon of iodine-fortified salt contains 284 micrograms of iodine.

Don't forget to check the label for iodine if you use medication, multivitamins, or other dietary supplements.

Excess iodine can harm people with Graves' disease or other autoimmune thyroid disorders. On the other hand, iodine deficiency may cause pregnancy-related problems, hypothyroidism, and goiter — an enlargement of the thyroid.

If you have a healthy thyroid or your doctor advises otherwise, you need a daily intake of 150 micrograms of iodine. Pregnant and breastfeeding women need more iodine because thyroid hormone is required for the baby’s bone and brain development.

Caffeine

Caffeine can accelerate the symptoms like rapid heart rate, anxiety, nervousness, and irritability. Thus, avoiding food or drinks containing caffeine, such as coffee, tea, soft drinks, cacao, and some supplements, is recommended.

People with hyperthyroidism should eat enough calories from nutritious foods. They are advised to avoid iodine-rich foods and low-calorie and protein consumption.

Please be aware that other thyroid disorders may cause hypothyroidism (underactive thyroid) or don't affect thyroid hormone production (euthyroidism). In these cases, proper nutrition will be slightly different.

Lastly, always consult with a healthcare professional to decide what foods to eat or avoid the management of your hyperthyroidism and symptoms.