Nutrition for Thyroid Health: Foods that Help and Harm
Your thyroid, a small, butterfly-shaped gland located in your lower neck, has enormous responsibility for your body’s metabolic processes. Specifically, your thyroid releases two primary hormones -- triiodothyronine (T3) and thyroxine (T4) -- that control metabolism.
When working properly, the T3 and T4 hormones travel through your bloodstream and help cells get energy from the food you eat. Thyroid hormones are also responsible for helping to regulate your body temperature and blood calcium levels, helping with growth and development and, during infancy, brain development.
For an estimated 27 million Americans, however, the thyroid produces either too much or too little hormone, which causes an array of health symptoms, some severe. But because thyroid disease is often misdiagnosed or simply overlooked, it’s estimated that more than half of affected Americans don’t know they have a problem.1
Who is Most Impacted by Thyroid Disease?
Women are much more likely to have thyroid problems than men, and may have up to a one in five chance of developing thyroid problems during their lifetime.2 The risk increases with age and family history, as well as:
- Having an autoimmune disease or a close relative with one
- Radiation exposure
- Thyroid surgery
- Going through menopause or perimenopause
- Recently having a baby
Hypothyroidism: The Most Common Thyroid Disease
Hypothyroidism (underactive thyroid) accounts for the majority of thyroid disease cases -- up to 80 percent according to some estimates. This condition occurs when your body produces too little thyroid hormone, leading to symptoms such as:3
- Fatigue and general sluggishness
- Unexplained weight gain
- Dry skin
- Increased sensitivity to cold
- Pain, stiffness or swelling in joints
- Achy muscles and muscle weakness
- Heavy menstrual periods
- Elevated blood cholesterol level
- Puffy face
- Brittle hair and nails
If left untreated, hypothyroidism can lead to obesity, joint pain, infertility, goiter (thyroid enlargement) and heart disease, but because the symptoms can mimic other diseases, or even be attributed to aging, many people do not realize the thyroid connection. Further, the symptoms may be mild at first, becoming increasingly severe only after a number of years, making them easy to overlook.
In the United States, hypothyroidism is most often the result of an autoimmune disease called Hashimoto’s thyroiditis, which causes your immune system to attack and destroy the thyroid. It’s thought that a virus, bacteria, genetics or a combination of environmental factors may contribute to Hashimoto’s. Worldwide, however, hypothyroidism is most often caused by an iodine-deficient diet.4
Other less common causes of hypothyroidism include:
- Radiation therapy used to treat head and neck cancers
- Thyroid surgery
- Treatment for hyperthyroidism
- Certain medications, including lithium
- Pregnancy (some women may produce antibodies to their thyroid during or after pregnancy)
- Pituitary gland disorder
- Congenital (about one in 3,000 U.S. babies are born with a defective, or missing, thyroid gland)
A blood test that measures your levels of thyroid-stimulating hormone (TSH) is typically used to diagnose hypothyroidism, and treatment usually involves taking a synthetic or natural thyroid hormone daily.
Hyperthyroidism: An Overactive Thyroid
With hyperthyroidism, your body produces too much thyroid hormone, leading to symptoms such as:
- Weight loss
- Nervousness, anxiety and irritability
- Increased perspiration
- Racing heart
- Hand tremors
- Difficulty sleeping
- Increased bowel movements
- Fine, brittle hair
- Muscle weakness, especially in the upper arms or thighs
Most often, hyperthyroidism is caused by an autoimmune disorder called Graves’ disease, in which your immune system produces antibodies that stimulate your thyroid, causing it to produce too much T4 hormone.
The exact cause of Graves’ disease is unknown, however it’s suspected that severe emotional stress may trigger the illness in some people.5 Family history may also be a factor.
Other causes of hyperthyroidism include overactive lumps in the thyroid or thyroiditis, an inflammation of the thyroid gland that can cause excess thyroid hormone to be released into your bloodstream.
A TSH blood test can typically diagnose hyperthyroidism, and the condition is usually treated with anti-thyroid drugs that block the gland’s ability to produce thyroid hormone, surgery, or radioactive iodine, which destroys overactive thyroid cells.6
Thyroid Nutrition: What Should You Eat for Thyroid Health?
As with virtually every bodily function, your diet plays a role in the health of your thyroid. There are some specific nutrients that your thyroid depends on and it’s important to include them in your diet:
Iodine: Your thyroid contains the only cells in your body that absorb iodine, which it uses to make the T3 and T4 hormones. Without sufficient iodine, your thyroid cannot produce adequate hormones to help your body function on an optimal level.
Iodine deficiency is typically not widespread in the United States because of the prevalent use of iodized salt. However, according to a nutrition evaluation conducted by the CDC, up to 36 percent of women of childbearing age may not get enough iodine from their diets,7 and it’s thought that iodine deficiency is on a slow but steady rise.
Because iodized salt is heavily processed, some recommend avoiding iodized salt and instead getting iodine naturally from sea vegetables (seaweed), such as hijiki, wakame, arame, dulse, nori, and kombu.
It should be noted, however, that too much iodine can actually trigger thyroid problems and worsen symptoms, so it’s important to have a healthy balance.
Selenium: This mineral is critical for the proper functioning of your thyroid gland, and is used to produce and regulate the T3 hormone. Selenium can be found in foods such as shrimp, snapper, tuna, cod, halibut, calf’s liver, button and shitake mushrooms and Brazil nuts.8
Zinc, Iron and Copper: These metals are needed in trace amounts for your healthy thyroid function. Low levels of zinc have been linked to low levels of TSH, whereas iron deficiency has been linked to decreased thyroid efficiency. Copper is also necessary for the production of thyroid hormones.9 Foods such as calf’s liver, spinach, mushrooms, turnip greens and Swiss chard can help provide these trace metals in your diet.
Omega-3 Fats: These essential fats, which are found in fish or fish oil, play an important role in thyroid function, and many help your cells become sensitive to thyroid hormone.10
Coconut Oil: Coconut oil is made up of mostly medium-chain fatty acids, which may help to increase metabolism and promote weight loss, along with providing other thyroid benefits.11 This is especially beneficial for those with hypothyroidism.
Antioxidants and B Vitamins: The antioxidant vitamins A, C and E can help your body neutralize oxidative stress that may damage the thyroid. In addition, B vitamins help to manufacture thyroid hormone and play an important role in healthy thyroid function.12
What Should You Avoid Eating for Thyroid Health?
There are certain foods that should be avoided to protect your thyroid function. These include:
Aspartame: There is concern that the artificial sweetener aspartame, sold under the brand name Nutrasweet, may trigger Graves’ disease and other autoimmune disorders in some people. The chemical may trigger an immune reaction that causes thyroid inflammation and thyroid autoantibody production.
Non-fermented Soy: Soy is high in isoflavones, which are goitrogens, or foods that interfere with the function of your thyroid gland. Soy, including soybean oil, soy milk, soy burgers, tofu and other processed soy foods, may lead to decreased thyroid function.
Fermented soy products, including miso, natto, tempeh and traditionally brewed soy sauce, are safe to eat, as the fermentation process reduces the goitrogenic activity of the isoflavones.
Gluten: Gluten is a potential goitrogen and can also trigger autoimmune responses (including Hashimoto’s thyroiditis) in people who are sensitive. Gluten is found in wheat, rye and barley, along with most processed foods.
You may have heard, too, that the isothiocyanates found in cruciferous vegetables like broccoli, cauliflower, cabbage and Brussels sprouts are goitrogens as well.
While it’s true that large amounts could interfere with thyroid function, especially if eaten raw, these veggies offer a myriad of other health benefits that make the benefits outweigh the risks for most people. If you know you have thyroid disease and want to be especially careful, steaming these vegetables will negate the goitrogenic effect, making them a healthy addition to your diet.
If you suspect you have thyroid disease, you should visit your health care practitioner for a full thyroid hormone panel. In fact, even if you don’t suspect you have a problem it’s a good idea to get tested as part of your regular checkups.
While some thyroid issues do have complicated underlying causes, you can help to maintain your thyroid health by making sure your diet includes the important, thyroid-healthy nutrients mentioned above.
Related Blog Posts:
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1, 2. Thyroid.About.com “Thyroid Disease 101” June 19, 2006
3.. MayoClinic.com Hypothyroidism Symptoms
4. American Thyroid Association "Hypothyroidism FAQ"
5. American Thyroid Association “Graves’ Disease”
6. American Thyroid Association “Hyperthyroidism FAQ”
7, 9, 12. WomentoWomen.com “The Simplest Way to Support Thyroid Health – Food!”
8. World’s Healthiest Foods “Selenium”
10. Thyroid.About.com “Fats That Heal, Fats That Kill”
11. Mercola.com “How to Help Your Thyroid With Virgin Coconut Oil"
13. Suite101.com “Thyroid Disease Triggers” March 21, 2006