<p> Hashimoto Thyroiditis: Is Nutrition Intervention Beneficial?</p><p>Hashimoto thyroiditis (HT), also known as Hashimoto’s disease, is the most common cause of primary hypothyroidism. HT is a chronic autoimmune disease in which the immune system attacks the thyroid gland. It affects women more than men, and most people affected have these related symptoms: moderate weight gain, cold intolerance, fatigue, dry skin and hair, forgetfulness, constipation, and amenorrhea (absence of menstrual periods, or heavy menstrual bleeding). Occasionally, early-onset HT results in hyperthyroidism and related symptoms, which include nervousness, intolerance to heat, and heart palpitations. Primary treatment for HT involves taking prescribed synthetic thyroid hormone medication; however, nutrition therapy can also be part of the treatment plan.</p><p>Diagnosis Hashimoto thyroiditis is diagnosed by blood work to determine thyroid function. The most common are for free thyroxine (T4), thyroid-stimulating hormone (TSH). Testing for the presence of thyroid autoantibodies may also be done. An ultrasound test can also be used to examine the current size of the thyroid gland and identify autoimmune inflammation.</p><p>Risk factors and triggers Hashimoto’s affects approximately three times more women than men. It is most commonly diagnosed between the ages of 30 to 50 years, and many people who develop HT have a genetic predisposition. Individuals with other autoimmune diseases, such as type 1 diabetes, celiac disease, lupus, Addison’s disease, rheumatoid arthritis, and autoimmune hepatitis are more likely to develop HT. Conversely, people with HT are at increased risk of developing these other autoimmune conditions.</p><p>Other identified triggers for HT include:  Excessive iodine intake  Certain drugs: lithium, interferon-alpha  Certain environmental toxicants: polyaromatic hydrocarbons (chemicals that are released from burning coal, oil, gasoline, trash, tobacco, wood, or other organic substances such as charcoal-broiled meat), or polyhalogenated biphenyls (chemicals used in industrial applications, or pesticides)  Infections: Hepatitis-C, parvovirus, rubella, herpes simplex virus, Epstein-Barr virus</p><p>Disease management There is no cure for HT, but lifelong treatment with a prescription of synthetic thyroid hormone (levothyroxine), can maintain normal thyroid hormone levels, which should be monitored regularly by one’s treating clinician, to manage the condition. Untreated hypothyroidism can lead to heart disease, infertility, increased risk of birth defects in pregnant women, depression, and behavioral impairment. </p><p>Medical nutrition therapy for HT should focus on a nutrient-rich, whole-food, anti-inflammatory eating plan. Appropriate energy intake and regular physical activity is important to achieve and/or maintain a healthy weight. Keep in mind that many people with HT tend to gain weight easily and have difficulty losing weight, especially if thyroid hormone levels are unbalanced. HT is also associated with increased risk of vitamin D and B12 deficiency, so foods rich in these vitamins, such as fatty fish, eggs, and milk, or supplementation should be suggested. </p><p>People who take thyroid medication should be advised that calcium supplements and certain foods such as soybean flour, soy, grapefruit juice, espresso coffee, millet, cottonseed meal, walnuts, and a sudden change to a high-fiber diet may interfere with absorption of levothyroxine from the gastrointestinal (GI) tract. Also, the medication is best absorbed on an empty stomach, at least 30 minutes to one hour before breakfast or before bed. </p><p>Both zinc and selenium are required for the synthesis of thyroid hormones, and thyroid hormone is also required for the absorption of zinc. Case studies have shown improvement in thyroid function in people who are deficient in these minerals. In a randomized, double-blind, controlled trial of 68 female hypothyroid subjects without deficiency, researchers determined that supplementing with either 30 milligrams (mg) zinc alone, or in combination with 200 micrograms (mcg) selenium resulted in a small improvement in thyroid function. (Mahmoodianfard, et al, 2015)</p><p>Hashimoto’s and celiac disease There is a strong association between celiac disease and HT. It is estimated that in individuals with celiac disease, the risk of thyroid disease is three times as high as in the general population. Likewise, those with autoimmune thyroid disease (HT or Grave’s disease) are at increased risk of celiac disease. People with HT with any signs or symptoms of celiac disease, such as iron-deficiency anemia, low vitamin D, bone or joint pain, dermatitis herpetiformis (an itchy skin rash), fatigue, or abdominal pain, should be encouraged to discuss being screened for celiac disease with their healthcare provider.</p><p>While a gluten-free diet will help to manage celiac disease, research is mixed as to whether the same diet will prevent or manage HT. Some studies have shown a decrease in thyroid antibodies after several years, or even a normalization of thyroid function after one year on a gluten-free diet, but other studies report that even with a gluten free diet, people with celiac disease individuals may still develop HT. (Metso, et al, 2012; Sategna-Guidetti, et al, 2001)</p><p>People with celiac and HT should be advised that strict adherence to a gluten-free diet will improve absorption of thyroid medication. Research has shown that people with celiac disease who follow a gluten-free diet while staying on the same dose of thyroxine had decreased TSH levels, indicating that their absorption of thyroxine had improved. (Virili, et al, 2012)</p><p>Guidelines for dietitians When working with people with HT, a dietitian should do an assessment for vitamin and mineral status and consider supplementation if indicated. People should also be educated about the potential health risks of HT, including heart disease from elevated cholesterol and blood pressure, and they should be encouraged to make changes in their eating habits and food choices to reduce this risk. </p><p>Although evidence on a gluten-free diet as a complementary therapy is mixed, this type of diet may have other health benefits for people with HT, particularly if there is underlying gluten sensitivity. If people with HT choose to follow a gluten-free diet, they should be aware that many commercially available gluten-free products may be high in calories from added sugars and fats. </p><p>Instead of choosing these types of foods, they should be educated about the benefits and encouraged to focus on an anti-inflammatory, whole-foods diet that is rich in naturally gluten- free foods such as fruits, vegetables, lean proteins, healthy fats from avocados, nuts and seeds, and gluten-free grains such as brown or wild rice, quinoa, and sorghum. Those who take thyroid medication should be advised to have their thyroid levels monitored more closely if making major changes in their diet that result in significantly increased fiber intake, as the amount of medication in the blood may decrease, and symptoms of hypothyroidism may occur.</p><p>References and recommended reading</p><p>Hashimoto thyroiditis. Merck Manual website. http://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/thyroid- disorders/hashimoto-thyroiditis. Accessed December 26, 2016.</p><p>Lauret E, Rodrigo L. Celiac disease and autoimmune-associated conditions. Biomed Res Int. 2013:127589. doi:10.1155/2013/127589.</p><p>Mahmoodianfard S, Vafa M, Golgiri F, Khoshniat M, Gohari M, Solati Z, Djalali M. Effects of zinc and selenium supplementation on thyroid function in overweight and obese hypothyroid female patients: a randomized double-blind controlled trial. J Am Coll Nutr. 2015;34(5):391-9. doi:10.1080/07315724.2014.926161.</p><p>Metso S, Hyytiä-Ilmonen H, Kaukinen K, Huhtala H, Jaatinen P, Salmi J, Taurio J, Collin P. Gluten- free diet and autoimmune thyroiditis in patients with celiac disease. A prospective controlled study. Scand J Gastroenterol. 2012;47(1):43-8. doi:10.3109/00365521.2011.639084.</p><p>Naiyer AJ, Shah J, Hernandez L, et al. Tissue transglutaminase antibodies in individuals with celiac disease bind to thyroid follicles and extracellular matrix and may contribute to thyroid dysfunction. Thyroid. 2008;18(11):1171-8. doi:10.1089/thy.2008.0110.</p><p>Sategna-Guidetti C, Volta U, Ciacci C, et al. Prevalence of thyroid disorders in untreated adult celiac disease patients and effect of gluten withdrawal: an Italian multicenter study. Am J Gastroenterol. 2001;96(3):751-7. doi:10.1111/j.1572-0241.2001.03617.x. Virili C, Bassotti G, Santaguida MG, et al. Atypical celiac disease as cause of increased need for thyroxine: a systematic study. J Clin Endocrinol Metab. 2012;97(3):E419-22. doi:10.1210/jc.2011-1851.</p><p>Zaletel K, Gaberšček S. Hashimoto’s thyroiditis: from genes to the disease. Curr Genomics. 2011;12(8): 576–588. doi:10.2174/138920211798120763.</p><p>Contributed by Anne Danahy, MS, RDN Review date: 1/16/17</p>