The term hypothyroidism is a medical condition in which the thyroid gland does not produce sufficient metabolism-regulating hormones, such as thyroxine. According to the National Center for Biotechnology Information, the most common cause of hypothyroidism is Hashimoto's thyroiditis, an autoimmune disorder characterized by inflammation of the thyroid gland. Risk of developing the condition increases with age, particularly for women over the age of 50. However, since signs of an underactive thyroid -- fatigue, dry skin, mild depression and weight gain -- mimic the symptoms of menopause or simply aging, only blood tests can rule out hypothyroidism. In addition to medication, talk to your doctor about including dietary measures in your treatment plan.
Diet Basics
Mayo Clinic endocrinologist Todd B. Nippoldt, M.D. says that there is no evidence that specialized diets for people with hypothyroidism are of any benefit, despite persistent claims that eating certain foods can enhance thyroid function. However, Nippoldt notes that some foods, as well as vitamin supplements and medications, can interfere with your body's ability to absorb synthetic thyroid hormone therapy, the standard treatment for underactive thyroid. Specifically, he advises that you avoid taking thyroid hormone within several hours of taking other medications or consuming soybean flour, cottonseed meal, walnuts or supplements containing iron, calcium or fiber.
The Iodine Factor
Iodine deficiency is associated with hypothyroidism because it is required to manufacture the thyroid hormones triiodothyronine, or T3, and thyroxine, also known as T4. According to the Linus Pauling Institute Micronutrient Information Center, the Food and Nutrition Board of the Institute of Medicine has set the tolerable upper intake level of iodine for an adult at 1,100 mcg per day. In the U.S., iodine deficiency is rare since table salt contains sufficient amounts of this trace element. However, people with autoimmune-based hypothyroidism may have a deficiency due to a sensitivity or allergy to iodine. In contrast, a reasonably balanced diet rarely provides more than 1,000 to 2,000 mcg of iodine per day, but people who average an intake of 1,700 to1,800 mcg of iodine per day may exhibit elevated levels of thyroid stimulating hormone, or TSH, and are also at risk for hypothyroidism.
Role of Selenium
According to the Office of Dietary Supplements of the National Institutes of Health, plants are the primary dietary source of selenium, another element required by humans to convert T4 thyroid hormone into T3. Selenium deficiency also worsens the effect of iodine deficiency or sensitivity on thyroid function. Other good sources of selenium include grain fed poultry and beef, tuna, pasta, rice and nuts, especially Brazil nuts.
High Value Protein
Leyla Muedin, M.S., R.D., C.D.N., says that high biological value protein is necessary to maintain normal thyroid function, which comes from meat, poultry, seafood, eggs and cheese. This is why people who consume a vegetarian or vegan diet are at risk for underactive thyroid. In addition, people who eat an abundance of soy or plants in the Brassica genus to compensate for the absence of animal protein risk impaired thyroid function because these foods, referred to as goitrogens, block iodine utilization. This is especially true for raw vegetables, so cook or steam them before eating.
