Top Thyroid Nutrients You Can’t Ignore
- The thyroid gland produces hormones that regulate the metabolism in every cell in the body.
- Low thyroid, or hypothyroidism, occurs when the thyroid doesn’t produce enough of these hormones. Hypothyroidism can cause brain fog, cold intolerance, depression, extreme fatigue, forgetfulness, thinning hair, and slowed heart rate.
- Iron, zinc, selenium, and iodine all play a vital role in thyroid health and a deficiency in any of these nutrients could cause hypothyroidism.
by Dr. John Neustadt
The thyroid is a butterfly-shaped gland at the base of the neck that produces two hormones, levothyroxine (T4) and triiodo-thyronine (T3). About 80% of thyroid hormones produced is T4 and about 20% is T3. T4 is inactive and is converted in tissues throughout the body into the active T3 hormone.
These chemical messengers regulate metabolism in every cell in the body, effecting your bones, blood, digestion, mood, memory, hair and energy.1 The production and release of T4 and T3 is controlled by thyroid-stimulating hormone (TSH), which comes from the pituitary gland in the brain.2
When the thyroid produces fewer hormones than your body needs, it’s called hypothyroidism.3 Due to the gland’s full-body link, poor thyroid health creates a ripple effect that impacts the entire body.4
Hypothyroidism and subclinical hypothyroidism affect nearly 5% of the United States population ages 12 and older. This number increases with age. Hypothyroidism is defined as having low levels of thyroid hormones, while in subclinical hypothyroid T4 and T3 are normal but TSH is elevated. An elevated TSH means the brain is having to produce more TSH than normal to stimulate the thyroid hormone to create enough T4 and T3.
According to the American Academy of Family Physicians, roughly one in every 300 adults has hypothyroidism and as much as 20% of women over 60 years old suffer from low thyroid function.5,6 While we don’t know definitively why, hypothyroidism affects far more women than men.
Since thyroid hormones affect every cell in the body and symptoms of low thyroid mimic other conditions, hypothyroid can often go unrecognized and be confused for other issues. Hypothyroid often develops slowly, so it often takes people months or even years to notice the symptoms. Low thyroid can cause fatigue, weight gain, a puffy face, cold intolerance, joint and muscle pain, constipation, dry skin, dry, thinning hair, depression and decreased heart rate.7 Hypothyroid can also elevate cholesterol, which may increase heart disease and stroke risk.8
And as if that weren’t enough, other symptoms include memory loss, constipation, infertility, brain fog, muscle weakness, poor circulation, lightheadedness, visual disturbances, difficulty processing information and decreased motivation. Making thyroid disorders even trickier to identify, symptoms can vary with age. For example, older adults may notice a decrease in cognitive function as the only symptom.
While radiation therapy around the head or neck and certain autoimmune diseases can cause low thyroid,9 a diet deficient in nutrients crucial for thyroid health is a common culprit. Selenium, iodine, iron, niacin, zinc and vitamin E are all required for healthy thyroid function; however, the American diet is consistently deficient in vitamins and minerals.10 Processed foods, including white rice, pasta, potato chips, and baked goods that use white flour contain almost no vitamins and minerals.11,12 That’s largely due to the fact that about 76% of iron, 16% of selenium and 78% of zinc is lost during the refining process that turns whole wheat into white flour for such products as breads, muffins, cookies and pizza dough.13,14
A recent Centers for Disease Control and Prevention Nutrition Report found that 10% of Americans are nutrient deficient, with iron being the second most common nutrient missing from Americans’ diets.15 While taking an iron dietary supplement can help restore healthy levels of iron and oxygen-carrying red blood cells, consuming the essential mineral through iron-rich foods is important. According to the U.S. National Institutes of Health (NIH) Office of Dietary Supplements, iron has relatively low bioavailability, so choosing foods with the right type of iron is key to maintaining healthy iron levels.16
Emphasizing iron-rich foods in your diet can help improve iron levels. Highly bioavailable iron is found in red meat and seafood, while certain types of nuts, beans, and vegetables contain less bioavailable (nonheme) iron that can still help keep iron levels healthy. Oysters, white beans, dark chocolate, tofu, spinach, and beef liver, for example, all contain at least 3 mg of iron per serving.
Age and biological sex determine how much iron a person needs. Most notably, due to iron losses through menstrual blood, women of reproductive age need significantly more iron (18mg/day) than men (8mg/day).17 As a result, iron deficiency is more common among women than men.
Iron deficiency is the most common cause of anemia, a condition in which a lack of red blood cells or hemoglobin causes extreme fatigue. Iron-deficiency anemia accounts for at least 50% of all cases of anemia globally.18 Anemic people don’t get enough oxygen delivered to brain and muscle tissues and as a result, an estimated 1.62 billion people worldwide suffer from fatigue, shortness of breath, rapid heart rate, dizziness, depression, decreased cognitive function, and feeling cold as a result.19
Anemia is also often the first signs of hypothyroidism. That’s because the thyroid needs iron to produce adequate amounts of T3 and T4. A 2012 study published in Endocrine Journal found that as many as 43% of people with hypothyroidism and 39% with subclinical hypothyroid were anemic, as opposed to 26% in the general population.20
Healthcare providers can order a simple, routine blood test to determine whether or not a patient needs more iron. The complete blood count (CBC) screens for anemia by testing blood for white and red blood cells as well as hemoglobin, a protein in red blood cells that delivers oxygen from the lungs to the rest of the body. However, it’s important to understand that you can have iron deficiency, and the symptoms of iron deficiency, without it showing up on a CBC test. The most sensitive indicator of iron status is a serum ferritin test. For more information, read my blog, The Most Important Lab Test Women Aren’t Getting.
Iodine is found in every tissue in the body and is required for the thyroid gland to produce thyroid hormone. A 2018 review of National Health and Nutrition Examination Survey data found U.S. dietary iodine intake has drastically decreased since 1974, halving in the past three decades.21,22
Today, urinary iodine concentrations among women of reproductive age in the U.S. is below World Health Organization recommendations.23 Alarmingly, a 2017 study published in Toxicology and Applied Pharmacology estimated that 21-44% of American women in their third trimester of pregnancy had inadequate iodine.24
This is particularly important because the hormones released by the thyroid are required for normal neurological developing during pregnancy and early childhood and even a mild iodine deficiency can impair cognitive function.25,26 But iodine also plays a role in breast health. Iodine deficiency is associated with fibrocystic breast disease (fibrous, dense, painful breast tissue), which can be effectively reversed or prevented with iodine supplementation.27 At least 50% of women of child-bearing age have fibrocystic breast disease, which is associated with an increased risk for developing breast cancer.28
The U.S. NIH recommends that adults over the age of 19 as well as pregnant women should consume 1,100 mcg of iodine every day.29 Eating iodine-rich foods is the best way to maintain healthy levels of the nutrient. Seaweed is the richest source of iodine because it grows in iodine-rich seawater, and seafood is typically high in iodine for the same reason.30 Dairy products are also often rich in iodine across the board; however, there are compelling health reasons to remove dairy from your diet. The amount of iodine in fruits and vegetables varies widely, depending on the iodine content of the soil in which the food was grown.
More than 70 countries, including the U.S., have iodized salt programs. Iodized table salt was introduced in the U.S. in the 1920s and historically was an effective way to combat iodine deficiency in the country. However, though it’s very common among manufacturers, fortifying table salt with iodine is voluntary in the U.S., and table salt accounts for just a small percentage of salt intake nationwide. It’s estimated that about 70% of the table salt in the U.S. is iodized, but table salt accounts for just 15% of average total daily salt intake.31 For this reason, and other health reasons, people should not rely on fortified salt to meet their daily iodine needs.
Selenium is a mineral with many biological functions. Not only is it crucial for the thyroid gland, but it has important roles in the body’s antioxidant systems. In adults, the thyroid has a higher amount of selenium per gram of tissue than any other organ and it’s involved in producing thyroid hormones and converting T4 to T3 throughout the body.32
Protein-rich foods including dairy products, nuts, cereals, seafood, and meat typically contain the most selenium, while protein-poor vegetables typically do not contain much selenium. Sea salt, eggs, yeast, bread, mushrooms, giblets, garlic, asparagus, and kohlrabi are all great sources of this mineral. Like iodine, the selenium content in food varies depending on the amount of selenium in the soil in which it was grown.33
Selenium deficiency in the U.S. is considered extremely rare. Most Americans get plenty of selenium from their diet because their food comes from geographically dispersed areas so there will natural be higher amounts of selenium in some food products that are products in selenium-rich soil.34 Selenium deficiency is notably common in China, where soil across the country lacks the element.35 People undergoing kidney dialysis, those living with HIV, and people who eat only local foods grown in soils that are low in selenium are also at risk of selenium deficiency.
The NIH Office of Dietary Supplements recommends that people over the age of 14 should consume 55 mcg of selenium daily and pregnant women consume 60 mcg and 70 mcg per day while breastfeeding.36
There is a bit of a symbiotic relationship that exists between zinc and thyroid hormones. Zinc is required to convert T4 into T3 and the absorption of zinc by the intestines needs thyroid hormone. Therefore, low zinc and cause hypothyroidism and hypothyroidism can in turn contribute to a zinc deficiency.37 A 2010 study showed that increasing zinc intake significantly improved T3 production in humans.38
Zinc deficiency is rare in the US but is quite common in low- and middle-income countries in Africa, Latin America, Asia and the Caribbean, where an estimated 2 billion people are zinc deficient.39
Adult males require slightly more zinc (11 mg) than females (8mg), and pregnant women should consume between 11 mg and 12 mg of zinc daily.40 While red meat and poultry provide the lion’s share of zinc consumed in the American diet, oysters contain more zinc per serving than any other food––more than 10 times more per serving than beef.41 Beans, nuts, crab, lobster, and dairy products are also good sources of the mineral.
Although diet is the first place a person from which a person’s nutrition should come, when more is required than what people can consistently get from their diets, dietary supplements can provide extra nutrients to promote your health.
If You Liked This, You Might Also Like
1 How does the thyroid gland work?. Institute for Quality and Efficiency in Health Care (IQWiG). 2018 April 19. [Article]
2 TSH (Thyroid-stimulating hormone) Test. U.S. National Library of Medicine. 2019 September 27. [Article]
3 How does the thyroid gland work?. Institute for Quality and Efficiency in Health Care (IQWiG). 2018 April 19. [Article]
4 Hypothyroidism (Underactive Thyroid). National Institute of Diabetes and Digestive and Kidney Diseases. Accessed 28 December 2019. [Article]
5 Gaitonde DY, Rowley KD, Sweeney LB. Hypothyroidism: an update. Am Fam Physician. 2012;86(3):244-251. [Article]
6 Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The Colorado thyroid disease prevalence study. Arch Intern Med.2000;160(4):526-534. [Article]
7 Hypothyroidism (Underactive Thyroid). National Institute of Diabetes and Digestive and Kidney Diseases. Accessed 28 December 2019. [Article]
8 Duntas LH, Brenta G. A Renewed Focus on the Association Between Thyroid Hormones and Lipid Metabolism. Front Endocrinol (Lausanne). 2018;9:511. [Article]
9 Hypothyroidism (underactive thyroid). Mayo Clinic. Accessed 29 December 2019. [Article]
10 National Center for Environmental Health, Centers for Disease Control and Prevention. CDC’s Second Nutrition Report: A comprehensive biochemical assessment of the nutrition status of the U.S. population. 2012 March 16. [Report]
11 Reddy MB, Love M. The impact of food processing on the nutritional quality of vitamins and minerals. Adv Exp Med Biol. 1999;459:99-106. [Article]
12 Agte V, Tarwadi K, Mengale S, Hinge A, Chiplonkar S. Vitamin profile of cooked foods: how healthy is the practice of ready-to-eat foods? Int J Food Sci Nutr. 2002;53(3):197-208. [Article]
13 Nesheim RO. Nutrient changes in food processing. A current review. Fed Proc. 1974;33(11):2267-2269. [Article]
14 Schroeder HA. Losses of vitamins and trace minerals resulting from processing and preservation of foods. Am J Clin Nutr. 1971;24(5):562-573. [Article]
15 National Center for Environmental Health. Centers for Disease Control and Prevention. CDC’s Second Nutrition Report: A comprehensive biochemical assessment of the nutrition status of the U.S. population. 2012 March 16. [Report]
16 National Institutes of Health Office of Dietary Supplements. Iron Fact Sheet for Professionals. 2019 October 16. [Article]
17 Egli, Ines and Richard Hurrell. Iron bioavailability and dietary reference values. The American Journal of Clinical Nutrition. Pages 1461S-1467S. 2010 March 3. [Article]
18 Ludwig H, Evstatiev R, Kornek G, et al. Iron metabolism and iron supplementation in cancer patients. Wien Klin Wochenschr. 2015;127(23-24):907-919. [Article]
19 Namaste SM, Rohner F, Huang J, et al. Adjusting ferritin concentrations for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project. Am J Clin Nutr. 2017;106(Suppl 1):359S-371S. [Article]
20 Mehmet, Erdogan and Kosenli Aybike and Sencer Ganidagli and Kulaksizoglu Mustafa. Characteristics of anemia in subclinical and overt hypothyroid patients. J-STAGE : endocrj 60 4 pp.541-541. [Article]
21 Glo The Iodine Global Network. Global scorecard of iodine nutrition in 2019 in the general population based on school-age children (SAC). IGN: Zurich, Switzerland. 2019. [Report]
22 Leung Angela M. and Elizabeth N. Pearce and Lewis E. Braverman and Alex Stagnaro-Green. AAP Recommendations on Iodine Nutrition During Pregnancy and Lactation. Pediatrics October 2014, 134 (4) e1282. [Article]
23 Panth, Pallavi and Gena Guerin and Nancy M. DiMarco. A Review of Iodine Status of Women of Reproductive Age in the USA. Biological Trace Element Research (2019) 188:208–220. [Article]
24 Lumen A, George NI. Estimation of iodine nutrition and thyroid function status in late-gestation pregnant women in the United States: Development and application of a population-based pregnancy model. Toxicol Appl Pharmacol. 2017;314:24-38. [Article]
25 Leung Angela M. and Elizabeth N. Pearce and Lewis E. Braverman and Alex Stagnaro-Green. AAP Recommendations on Iodine Nutrition During Pregnancy and Lactation. Pediatrics October 2014, 134 (4) e1282. [Article]
26 Perrine, Cria G. and Kirsten Herrick and Mary K. Serdula and Kevin M. Sullivan. Some Subgroups of Reproductive Age Women in the United States May Be at Risk for Iodine Deficiency. The Journal of Nutrition, Volume 140, Issue 8, August 2010, Pages 1489–1494. [Article]
27 Rappaport J. Changes in Dietary Iodine Explains Increasing Incidence of Breast Cancer with Distant Involvement in Young Women. J Cancer. 2017;8(2):174-177. [Article]
28 Ghent WR, Eskin BA, Low DA, Hill LP. Iodine replacement in fibrocystic disease of the breast. Can J Surg. 1993;36:453–460 [Article]
29 National Institutes of Health Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. 2019 July 9. [Article]
30 Panth, Pallavi and Gena Guerin and Nancy M. DiMarco. A Review of Iodine Status of Women of Reproductive Age in the USA. Biological Trace Element Research (2019) 188:208–220. [Article]
31 Maalouf, Joyce and Jessica Barron and Janelle P. Gunn and Keming Yuan and Cria G. Perrine and Mary E. Cogswell. Iodized Salt Sales in the United States. Nutrients. 2015 Mar; 7(3): 1691–1695. [Article]
32 Ventura, Mara and Miguel Melo and Francisco Carrilho. Selenium and Thyroid Disease: From Pathophysiology to Treatment. Int J Endocrinol. 2017; 2017: 1297658. [Article]
33 Kieliszek, Marek. Selenium–Fascinating Microelement, Properties and Sources in Food. Molecules. 2019 Apr; 24(7): 1298. [Article]
34 National Institutes of Health Office of Dietary Supplements. Selenium Fact Sheet for Consumers. 2019 December 10. [Article]
35 Centers for Disease Control. National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002. Pages 101-105. [Report]
36 National Institutes of Health Office of Dietary Supplements. Selenium Fact Sheet for Consumers. 2019 December 10. [Article]
37 Ambooken Betsy and MP Binitha and S Sarita. Zinc Deficiency Associated with Hypothyroidism: An Overlooked Cause of Severe Alopecia. Int J Trichology. 2013 Jan-Mar; 5(1): 40–42. [Article]
38 Ertek, Sibel and Arrigo FG Cicero and Omur Caglar and Gurbuz Erdogan. Relationship between serum zinc levels, thyroid hormones and thyroid volume following successful iodine supplementation. HORMONES 2010, 9(3):263-268. [Article]
39 Zinc. Linus Pauling Institute Micronutrient information Center. Oregon State University. [Web page]
40 Ertek, Sibel and Arrigo FG Cicero and Omur Caglar and Gurbuz Erdogan. Relationship between serum zinc levels, thyroid hormones and thyroid volume following successful iodine supplementation. HORMONES 2010, 9(3):263-268. [Article]
41 National Institutes of Health Office of Dietary Supplements. Zinc Fact Sheet for Health Professionals. 2019 July 10. [Web page]
Article at-a-glance: While medications can be helpful, they aren’t without risks. Knowing your options and who can help when a problem arises is crucial. Just like not all doctors are the same, neither are all pharmacists. Understanding the difference is important....
Article at-a-glance: Fifty-five percent of Americans now take at least one drug and almost 12% take five or more prescriptions drugs. Doctors and pharmacists almost never discuss drug-induced nutrient depletions with patients even though the fix is easy--simply take...
Article at-a-glance: Nearly half of Americans used at least one prescription drug in the last 30 days, and three-quarters of visits to the doctor include discussion and prescription of medications. One serious hidden risk of a wide range of medication is osteoporosis...