Certain foods can contribute to poor thyroid function. Your thyroid gland produces hormones that allow your body to use energy stores in response to low calorie intake or increased need during exercise recovery, sickness or wound healing. Your body requires iodine to produce thyroid hormones. Some raw vegetables, fruits and nuts contain chemicals called goitrogens, which can lower the amount of iodine you absorb from food.
Thyroid Hormones and Foods
Low levels of thyroid hormones can result in a condition called hypothyroidism. When your body does not produce enough thyroid hormones, you might unexpectedly gain weight, have a low body temperature, feel fatigued, get sick frequently, and have brittle fingernails and hair, and thin skin. Your doctor can perform tests to assess your thyroid function.
Your body can get iodine from foods such as iodized salt, milk and other dairy, meat, saltwater fish, sea vegetables, and lower amounts from some fruits and vegetables. Certain foods contain chemicals called goitrogens, which inhibit your body's ability to absorb iodine. Goitrogens from foods might contribute to or worsen hypothyroidism, but are unlikely to cause hypothyroidism on their own.
Cruciferous Vegetables
All vegetables of the genus Brassica contain goitrogens. These include all types of cabbage, bok choy, broccoli, cauliflower, Brussels sprouts, canola oil, collard greens, horseradish, kale, kohlrabi, mustard greens, radishes, turnips and rutabagas. Cooking will inactivate goitrogens in foods. Limit your intake of raw cruciferous vegetables.
Soy
Uncooked soy products, including soybeans, tofu, soybean oil, soy flour and soy lecithin, have been shown to contain some levels of goitrogens. This is especially problematic as soybean oil, flour and lecithin are added to most processed foods in some form. Vegetarians who rely on soy as a protein source might need to take special consideration to obtain adequate levels of iodine, possibly from sea vegetables such as seaweed and kelp.
Other Foods
Other foods that contain goitrogens when uncooked include pine nuts, peanuts, millet, strawberries, pears, peaches, spinach, bamboo shoots and sweet potatoes. If your doctor has found that you have hypothyroidism or iodine deficiency, he might instruct you to limit these foods in raw forms.
Eating for Thyroid Function
Most of these foods are only lightly goitrogenic and are healthy to eat, and most people do not need to avoid these foods except in large quantities when raw. During treatment for hypothyroidism, your doctor will give you specific dietary recommendations based on your individual health. When taking synthetic thyroid hormones, avoid taking your medication with a high fiber meal, as this might decrease the absorption of hormones.
