The Best Foods for Your Thyroid

Nutritional deficiencies can play a significant role in thyroid problems.  That’s because certain nutrients are needed both to produce T4, the inactive form of thyroid hormone, and to convert T4 to T3, the active hormone.

Here are some of the best foods for your thyroid.

Seaweed (kelp, dulse, hijiki, nori, arame, wakame, kombu) and shellfish (shrimp, mussels) all contain iodine, a nutrient needed for your thyroid gland to be able to make both T3 and T4. The RDA for iodine is 150 micrograms. (It’s 220 mcg during pregnancy and 290 mcg during breastfeeding.  Whether or not most people in the US get enough iodine is open to debate. The National Health and Nutrition Examination Survey (NHANES) done in 2008, showed that about 10% of people in the U.S. are very deficient in iodine.  That’s a very significant number since only about 3% of the population has hypothyroidism.

There are blood and urine tests to check for deficiency. Most people get iodine from iodized salt and processed foods made with iodized salt, which has 77 mcg of iodine per gram. High dose iodine can be very helpful to some patients but is best done under medical supervision, since it can rarely have some unwanted effects, such as iodine-induced hyperthyroidism. Amounts of iodine in seaweed and shellfish vary widely, but for thyroid support, one serving a day is generally safe and adequate.

Clams and liver are great sources of iron, another nutrient needed to produce thyroid hormones (affecting production of T4 as well as conversion to T3). One serving of clams (3 ounces) has 23 mg of iron, while three ounces of beef liver has 5.5 to 10 mg of iron. Research shows that people with low thyroid function respond best when they get both iodine and iron. The RDA for iron is 8 mg a for adult men and women past menopause, 18 mg a day for women of child-bearing age, 27 mg for pregnant women, and 10 mg for women who are breast-feeding. People most likely to be deficient are women of child-bearing age or people who have blood loss for any reason.

Brazil nuts, yellow fin tuna and halibut are all are top sources of selenium, a trace mineral that protects the thyroid from oxidative damage and is needed to convert T4, the inactive form of thyroid hormone, to T3, the active form. The RDA for adults is 55 mcg. One ounce of Brazil nuts (6-8 nuts) has about 540 mcg of selenium; 3 ounces of tuna, 92 mcg; halibut, 47 mcg. Selenium deficiency is seldom recognized or tested for, so it’s best to simply make sure you are eating selenium-rich foods or getting about 200 micrograms a day from a supplement.

Oysters, red meat and shellfish all contain zinc, which is involved in converting T4 to T3. Zinc is also needed by the hypothalamus to make the hormone it uses to signal the pituitary gland to activate the thyroid. People low in zinc can have an underactive thyroid gland. Three ounces of oysters has about 65 mg of zinc; 3 ounces of beef or a cup of cooked lobster meat, about 6 mg. The RDA is 11 mg for men, 8 mg for women. Most likely to be zinc-deficient: people who have GI issues such as Crohn’s or have had gastric bypass for weight loss; vegetarians, and alcoholics.

Swordfish, salmon, tuna, herring, sardines, egg yolks, and fortified milk all contain vitamin D, which helps to get thyroid hormone “signals” inside the nucleus of cells, where it can be put into action. Vitamin D deficiency is associated with an increased risk for autoimmune disorders of the thyroid. Three ounces of swordfish has 566 IUs of vitamin D; 3 ounces of salmon, 447 IUs; 3 ounces of pickled herring, 96 IUs. Milk has 100 IUs per cup. (Other dairy products, such as cheese and ice cream, are generally not fortified.) One large egg yolk has 42 IUs. The RDA is 600 IUs a day for adults up to age 70; 800 IUs for those ages 70 or older. Most likely to be deficient: people who are older, dark-skinned, have malabsorption problems, or are obese (vitamin D is “sequestered” in fat.) In fact, most people don’t get enough vitamin D from foods. Getting plenty of sunlight can provide up to 10,000 IUs of vitamin D a day, but most people don’t get much sun. So supplements are a good way to go. Take an amount that keeps your blood level at an optimal 50-80 ng/mL. This can be as much as 4,000-10,000 IUs a day for some people.

 

References

Kathleen L. Caldwell, Amir Makhmudov, Elizabeth Ely, Robert L. Jones, and Richard Y. Wang. Thyroid. April 2011, 21(4): 419-427

Choi YM, Kim WG, Kim TY, et al. Low Levels of Serum Vitamin D3 are Associated with Autoimmune Thyroid Disease in Pre-Menopausal Women.Thyroid. 2014 Jan 30.

Laurberg P, Cerqueira C, Ovesen L, et al. Iodine intake as a determinant of thyroid disorders in populations. Best Pract Res Clin Endocrinol Metab. 2010 Feb;24(1):13-27.

Pike JW, Meyer MB. Fundamentals of vitamin D hormone-regulated gene expression. J Steroid Biochem Mol Biol. 2013 Nov 12. pii: S0960-0760(13)00234-3.

Triggiani V, Tafaro E, Giagulli VA, et al. Role of iodine, selenium and other micronutrients in thyroid function and disorders. Endocr Metab Immune Disord Drug Targets. 2009 Sep;9(3):277-94.

Yoshida K, Kiso Y, Watanabe TK, et al. Erythrocyte zinc in hyperthyroidism: reflection of integrated thyroid hormone levels over the previous few months. Metabolism. 1990 Feb;39(2):182-6.

Zimmermann MB. The influence of iron status on iodine utilization and thyroid function. Annu Rev Nutr. 2006;26:367-89.

Zimmermann MB, Köhrle J. The impact of iron and selenium deficiencies on iodine and thyroid metabolism: biochemistry and relevance to public health. Thyroid. 2002 Oct;12(10):867-78.