According to the American Thyroid Association (n.d.), about 20 million people in the United States have a thyroid condition. Women are more likely than men to develop a thyroid condition. It is also more common for a thyroid condition to develop later in life.
I have had low thyroid function, also known as hypothyroidism, for over 10 years. Common symptoms include low metabolic rate, difficulty in losing weight, feeling cold, feeling tired or lethargic, hair loss, and dry skin, although there can be others.
Since I was first diagnosed, I have researched thyroid function and different factors that affect it. Keep in mind that every person is different, and what works for one person may not work for all of us. In general, there are certain foods that people with hypothyroidism should pay attention to.
Before I tell you about these foods, I’ll tell you about the thyroid gland, and provide you with more information about hypothyroidism.
Thyroid Gland & Hypothyroidism
The thyroid gland is part of the endocrine system and produces several hormones that support the body’s metabolism. These hormones also aid other systems, including the nervous, cardiovascular, muscular, skeletal, digestive, reproductive, and integumentary (skin) systems (Marieb & Hoehn, 2013). Both overactive (hyperthyroidism) and underactive thyroid function can affect our metabolism, but hyperthyroidism boosts it and hypothyroidism slows it down.
Hypothyroidism, or myxedema, results from an underactive thyroid, the removal of the thyroid gland, or insufficient iodine consumption (Marieb & Hoehn, 2013). It can be congenital, which means it is brought on from birth, or acquired, which means it is brought on after birth. When the symptoms are severe the condition is considered overt or clinical, and when they are less severe it is considered mild or subclinical (Roberts & Ladenson, 2004).
Thyroid Function and Iodine
The thyroid gland controls metabolic processes by releasing hormones. Iodine is an essential component of thyroid hormones, and 70% to 80% of the body’s iodine is stored in the thyroid gland (Schlenker & Roth, 2011). Iodine is needed to make the two main thyroid hormones, namely triiodothyronine (T3) and thyroxine (T4) (Mahan, Escott-Stump, & Raymond, 2012).
Iodine deficiency often causes a goiter, or an enlargement of the thyroid gland. This is due to the accumulation of thyroglobulin in the thyroid follicles, which over time causes a visible engorgement of the gland (Schlenker & Roth, 2011). Goiter can also be caused by goitrogens. Goitrogens block thyroid cells from being able to take up iodine (Mahan et al., 2012).
Treatment for hypothyroidism depends on symptoms and causes, but usually includes iodine supplements, thyroid hormone replacement therapy, levothyroxine, desiccated thyroid extract from pigs, selenium supplements, nutritional changes, exercise, stress management, and other lifestyle adjustments (Calabro, Costa, Foster, & Lee, 2012; Marieb & Hoehn, 2013).
Foods to Pay Attention To
People with hypothyroidism are encouraged to eat foods that provide iodine and selenium to the diet and avoid foods that are goitrogenic. Studies show that consumption of iodine-rich foods and fresh (not canned) fish and shellfish can reduce the risk of thyroid cancer, while consumption of cruciferous plants can increase the risk of thyroid cancer (Choi & Kim, 2014).
Good sources of iodine are iodized salt, Himalayan salt, seafood, wild-caught fish, including tuna and cod, seaweed, eggs, beans, potatoes, bananas, prunes, and dairy such as milk, cheese, and yogurt.
Too much iodine can disrupt thyroid function and reverse any benefits it provides, so be careful not to consume too much iodine.
Selenium is found in some fish and seafood, including tuna, halibut, salmon, sardines, mussels, shrimp, octopus, and squid. It is also found in beef, lamb, pork, liver, turkey, and chicken. Brazil nuts, sunflower seeds, spinach, mushrooms, and eggs are other options.
Goitrogenic components are found in plants within the mustard or Brassicaefamily, which include brassica-seed, rutabaga, turnip, cabbage, kale, rape plant, Chinese cabbage, Brussels sprout, broccoli, kohlrabi, cauliflower, and mustard (Greer, 1957). Goitrogenic substances are also found in peach, pear, strawberry, spinach, peanut, sweet potato, soybean, and carrot (Greer, 1957; Mahan et al., 2012).
Soy & Soy Products
Soy,Glycine max, belongs to the pea family and is a staple in Asian diets, and is often fermented and prepared into tempeh, miso, tofu, and soy sauce, among others.
Soy was touted as a health food for many years. It has properties that help fight cancer, lower blood pressure, lower cholesterol, protects against coronary heart disease and osteoporosis, and provides a natural alternative to hormone replacement therapy (Cheng, 2004; Sathyapalan et al., 2011; Ulbricht, 2010).
However, soy is also believed to play a negative role hormone-sensitive conditions, hormone-related cancers, and thyroid disorders (Ulbricht, 2010). One study stated that soy protein was linked to developing hypothyroidism (Calabro et al., 2012). Another stated that dietary soy interfered with the absorption of thyroxine medication for hypothyroidism treatment (Roberts & Ladenson, 2004). A third study stated that soy inactivated thyroid peroxidase or TPO, an enzyme involved in the liberation of iodine, and thus the synthesis of thyroid hormones (Kohlstadt, 2008; Sathyapalan et al., 2011).
It is useful to note that increasing intake of iodine or selenium through supplements or seaweed counteracted the effects of soy (Kohlstadt, 2008).
Hypothyroidism requires a treatment approach that includes medications, and supplements, and is best supported with lifestyle changes and healthy food choices. It is best if you test which foods work best for you, but in general I would encourage you to consume iodine-rich foods and selenium-rich foods, and discourage you from consuming goitrogenic foods, soy, and soy products.
American Thyroid Association. (n.d.) General information/press room. American Thyroid Association.Retrieved on April 16, 2018 from https://www.thyroid.org/media-main/about-hypothyroidism/
Calabro, A., Costa, S., Foster, M., & Lee, S. L. (2012). Alternative therapies for thyroid disease examined.Endocrine Today, 10(10), 22. Retrieved from http://search.proquest.com/docview/1114471373?accountid=158302
Choi, W. J. & Kim, J. (2014). Dietary factors and the risk of thyroid cancer: a review. Clinical Nutrition Research, 3(2), 75-88. Retrieved from http://dx.doi.org/10.7762/cnr.2014.3.2.75
Cheng, T. O. (2004). Soybean foods- the good, bad, and ugly.Journal of the National Medical Association, 96(9), 1240. Retrieved from http://search.proquest.com/docview/214059357?accountid=158302
Greer, M. A. (1957). Goitrogenic substances in food. The American Journal of Clinical Nutrition, 5(4), 440-444. Retrieved from http://ajcn.nutrition.org/content/5/4/440.long
Kohlstadt, I. (2008). Hypothyroidism: more seaweed, less soy, and a closer, potentially life-saving look at iodine. Townsend Letter, 305, 112-113. Retrieved from http://go.galegroup.com.ezp-01.lirn.net/ps/i.do?id=GALE%7CA189714622&v=2.1&u=lirn12711&it=r&p=GPS&sw=w&asid=cec63bbc418677898824fdfc734c3115
Mahan, L. K., Escott-Stump, S., & Raymond, J. L. (2012). Krause’s Food and The Nutrition Care Process(13thed.). St. Louis, MO: Elsevier Saunders.
Marieb, E.T., & Hoehn, K. (2013). Human Anatomy & Physiology (9thed.). Glenview, IL: Pearson Education.
Roberts, C. G. P., & Ladenson, P. W. (2004). Hypothyroidism.The Lancet, 363(9411), 793-803. Retrieved from http://search.proquest.com/docview/198999358?accountid=158302
Sathyapalan, T., Manuchehri, A. M., Thatcher, N. J., Rigby, A. S., Chapman, T., Kilpatrick, E. S., & Atkin, S. L. (2011). The effect of soy phytoestrogen supplementation on thyroid status and cardiovascular risk markers in patients with subclinical hypothyroidism: a randomized, double-blind, crossover study. The Journal of Clinical Endocrinology & Metabolism, 96(5), 1442-1449. http://dx.doi.org/10.1210/jc.2010-2255
Ulbricht, C. E. (2010). Natural Standard: Herb & Supplement Guide- An Evidence-Based Reference. St. Louis, MO: Elsevier Mosby.
Schlenker, E. D.& Roth, S. L. (2011). Williams’ Essentials of Nutrition and Diet Therapy- Revised Reprint (10thed.).St. Louis, MO: Elsevier Mosby.