Foods That Decrease Thyroid Function

The thyroid gland produces thyroid hormones, which regulate the body's metabolism. According to Mayo Clinic doctor Todd B. Nippoldt, M.D., there is no clear scientific connection between diet and thyroid production; however, there are foods that inhibit the absorption of iodine, which is critical to thyroid activity. These foods, known as goitrogens, may reduce or negate the the ability of the thyroid to produce hormones or hormone receptors. Goitrogens are high in sulphur, a mineral that, combined with iron and copper, helps keep the thryoid in balance. Those who subscribe to alternative or homeopathic remedies recommend that these types of foods be limited or avoided for optimum thyroid gland activity.

Soy

Non-fermented soy is known to inhibit thyroid production. These foods include raw tofu and soybeans as well as any foods that list soy isoflavones as an ingredient. It is important to read the labels of processed foods, as soy isoflavones or textured vegetable protein may be present in packaged products like protein shakes or bars and instant oatmeal.

Vegetables

Among the common vegetables that fall under the category of goitrogens are: broccoli; Brussels sprouts; cabbage; cauliflower; corn; lima beans; sweet potatoes; and turnips. Consuming large quantities of these vegetables raw may inhibit thyroid function, although if the vegetables are cooked, the effect is lessened or eliminated. In addition, other raw vegetables such as kale, mustard greens or spinach, may also inhibit thyroid activity.

Fruits

There are a few fruits that should be avoided for optimum thyroid activity. The most common are strawberries, but peaches, pears and rutabaga should be eaten in limited quantities. If you consume these vegetables cooked, the effect may be lessened or eliminated.

Other Things to Avoid

Some nuts, including peanuts and pine nuts, are classified as goitrogens and should be avoided. Red meat and eggs, both of which contain cysteine (an amino acid) may inhibit the absorption of iodine and should be eaten in moderation. In addition, it is recommended that you limit the consumption of black and green teas and tap water, all of which may contain fluoride and chlorine.

Hypothyroidism

If you have already been diagnosed with an underactive thyroid, or hypothyroidism, the above list of foods should definitely not be consumed within several hours of taking a thyroid replacement medication, according to Nippoldt. Since medications are a synthetic form of the thyroid hormone, it takes the body longer to absorb the hormone and absorption may be inhibited by giotrogens or minerals. In fact, the instructions on many synthetic thyroid replacements recommend taking the pills on an empty stomach for the best absorption.