A person's diet can have an effect on the symptoms of hyperthyroidism. Some foods can improve the condition, while others can make symptoms worse or interfere with medications.
Hyperthyroidism, a type of thyrotoxicosis, is a condition in which the thyroid gland produces too much thyroid hormone. Some people refer to this condition as an overactive thyroid. The most common cause of hyperthyroidism is an autoimmune condition called Graves' disease.
The symptoms of an overactive thyroid include unintentional weight loss, anxiety, sweating, frequent bowel movements, difficulty sleeping, and muscle weakness. Hyperthyroidism is much more common in women than in men.
In this article, we discuss how diet affects hyperthyroidism and provide lists of foods to eat and avoid.
Eating certain foods will not cure hyperthyroidism, but some nutrients and minerals play a role in managing the underlying condition. Diet can affect both the production of thyroid hormones and how the thyroid functions.
The following nutrients and chemicals are among those that can affect hyperthyroidism:
- Iodine, which the thyroid gland uses to produce thyroid hormone. Too much iodine in the diet can increase the production of thyroid hormone.
- Calcium and vitamin D are vital because hyperthyroidism can cause problems with bone mineral density.
- Foods and drinks containing caffeine can worsen the symptoms of hyperthyroidism.
Below, we discuss some of the nutrients that can affect thyroid function and note which foods contain them.
The following foods can have benefits for people with an overactive thyroid:
Low iodine foods
If a person is planning to receive radioactive iodine treatment for hyperthyroidism, their doctor may ask them to follow a low iodine diet.
Foods and drinks that are low in iodine include:
- noniodized salt
- egg whites
- fresh or frozen vegetables
- tea and black coffee
- herbs and spices
- vegetable oils
- sugar, jam, jelly, and honey
- unsalted nuts and nut butter
- soda and lemonade
- beer and wine
- moderate portions of beef, chicken, turkey, veal, and lamb
- fruit and fruit juices
The American Thyroid Association offer tips on how to follow a low iodine diet.
Some cruciferous vegetables
However, anyone with hypothyroidism (decreased thyroid function) should avoid eating large amounts of these foods.
These cruciferous vegetables include:
- Brussels sprouts and cabbage
- collard greens, mustard greens, and turnip roots and greens
- kale and arugula
- radishes and rutabagas
- bok choy
- broccoli and broccoli rabe
Foods containing selenium
Selenium is a micronutrient that the body requires for the metabolism of thyroid hormones. Research suggests that selenium can help improve some of the symptoms of autoimmune thyroid disease, such as thyroid eye disease.
Among people using anti-thyroid medications, those who take selenium supplements may achieve normal thyroid levels more quickly than those who do not.
Foods rich in selenium include:
- Brazil nuts
- fortified pasta and cereals
- cottage cheese
- baked beans
Foods containing iron
Iron is a nutrient that is important for normal bodily processes, including thyroid health. Iron helps the red blood cells carry oxygen to other cells in the body.
Researchers have linked low levels of iron to hyperthyroidism.
People can maintain an adequate intake of iron by including these foods in their diet:
- fortified cereals
- oysters and fish
- white beans, kidney beans, and black beans
- dark chocolate
- beef, chicken, turkey, and pork
Foods containing calcium and vitamin D
Calcium and vitamin D are both nutrients that are important for bone health.
Foods rich in calcium include:
- ice cream
- canned salmon
- fortified orange juice
- bok choy
- tofu and fortified soy milks
Many people with hyperthyroidism have vitamin D deficiency. The primary source of vitamin D is the sun hitting the skin so that the body can make its own. However, due to concerns about sun exposure and increased risk of skin cancer, many people actively limit their time in the sun or use sunscreen.
Not many foods are good sources of vitamin D, but the following foods contain some of this vitamin:
- salmon and tuna
- milk and some fortified dairy products (check the labels)
- fortified soy milk
- fortified cereals
Studies have linked certain spices, including turmeric and green chilis, to a reduced frequency of thyroid disease, including hyperthyroidism.
Turmeric also has anti-inflammatory properties.
People can use different spices, such as turmeric, to add flavor to their food.
Below, we look at the foods that can be harmful to people with hyperthyroidism if they eat them in large quantities:
Too much iodine can make hyperthyroidism worse by leading the thyroid gland to produce too much thyroid hormone.
A person with hyperthyroidism should avoid eating excessive amounts of iodine-rich foods, such as:
- iodized salt
- fish and shellfish
- seaweed or kelp
- dairy products
- iodine supplements
- food products containing red dye
- egg yolks
- blackstrap molasses
- carrageenan, which is an additive
- baked goods with iodate dough conditioners
Animal studies have shown that soy ingestion can interfere with radioactive iodine uptake for the treatment of hyperthyroidism.
Sources of soy include:
- soy milk
- soy sauce
- edamame beans
- soybean oil
The reason for this is not apparent, but genetics may play a role. Having celiac disease can also make a person more likely to develop other autoimmune disorders.
Celiac disease causes damage to the small intestine as a result of the ingestion of gluten. Gluten is a protein in wheat, barley, oats, and rye.
People with celiac disease need to follow a gluten free diet. Some research suggests that following a gluten free diet may facilitate better absorption of thyroid medications by the intestine and decrease inflammation.
Caffeine can worsen some symptoms of hyperthyroidism, including palpitations, tremors, anxiety, and insomnia.
Where possible, a person with hyperthyroidism should try to avoid foods and drinks containing caffeine. These include:
- regular coffee
- black tea
- regular soda
- energy drinks
Hyperthyroidism is a condition in which the thyroid gland is overactive and produces excess thyroid hormone. People should follow their treatment plan and any dietary recommendations from their doctor.
Changing the diet might improve symptoms of hyperthyroidism. Certain nutrients may help support healthy thyroid function or decrease hyperthyroidism symptoms.
A doctor or dietitian will be able to provide more information about dietary changes for hyperthyroidism.