Green vegetables, especially kale, contain chemicals called goitrogens that may inhibit absorption of dietary iodine. A decrease in iodine in your body can worsen symptoms of hypothyroidism, a condition where your thyroid gland does not produce enough hormones. The hormones produced by your thyroid gland are essential for regulating your metabolism. Goitrogens are almost completely destroyed during cooking, so avoid eating raw kale in excess with hypothyroidism.

Hypothyroidism

Hypothyroidism can be caused by iodine deficiency or damage to your thyroid gland. Located in your neck, your thyroid gland may swell during hypothyroidism, a condition called a goiter, from which goitrogens derive their name. Symptoms may include weight gain, cold sensitivity, poor healing, thickened skin, brittle nails and hair, frequent infections, mood disturbances and fatigue. Your doctor will measure levels of thyroid hormones in order to diagnose you with hypothyroidism. Treatment includes medication with synthetic thyroid hormones and careful control of iodine in diet.

Role of Iodine

Iodine is an essential mineral used primarily to produce thyroid hormones. When healthy, your thyroid gland stores sufficient amounts of iodine to produce the thyroid hormones that your body needs. Iodine can be found in meat, seafood, milk, dairy and most fruits and vegetables, although levels can vary with growing conditions. Iodine is also added to table salt, so deficiency in developed nations in rare in healthy people. Iodine deficiency may develop as a consequence of hypothyroidism, as your thyroid no longer stores iodine efficiently.

Goitrogens

Goitrogens are chemicals in food such as kale, cruciferous vegetables and soybeans. Many, but not all, green vegetables contain some levels of goitrogens. Even when eaten frequently, foods containing goitrogens will not cause thyroid disease in healthy people. You need only monitor goitrogen intake after you have been diagnosed with thyroid disease. Kale and green vegetables are very healthy foods, rich in nutrients, and do not need to be avoided completely. If you have thyroid disease, continue to eat these foods cooked. Dietary guidelines given by your doctor should take precedence.

Cooking Kale

Sautée kale with olive oil and garlic for a quick side dish. You can also mix kale with other greens, such as turnip greens, and simmer until tender. Kale can also be baked to make kale chips, a healthy snack. Tear small pieces of kale from the stems, coat lightly with oil and sprinkle with a small amount of seasoning salt. Bake the kale on a baking sheet at 350 F until crisp.