Nutritional & metabolic counseling, Benedicte Mai Lerche MSc PhD

Lesson 2

Anti -Thyroid foods & substances

Polyunsaturated fats inhibit the release of thyroid hormones from the gland, the transport of the hormones on proteins in the blood, and the tissue’s response to the active thyroid hormone T3. 

Carotenes are polyunsaturated hydrocarbons that block thyroid function in the same way as polyunsaturated fats.

Carrot juice and cooked carrots contain large amounts of carotene.
The amount of glucose in the liver cells regulates the activity of the liver enzyme that converts T4 into T3. If the liver cells doesn’t receive enough sugar, this conversion enzyme is inhibited resulting in hypothyroidism due to low T3 levels. In hypoglycemia (low blood sugar), diabetes (where glucose doesn’t enter cells efficiently), or prolonged fasting (where the liver’s sugar stores are depleted) hypothyroidism will occur because of inhibition of this conversion enzyme, resulting in a subnormal of T3 and symptoms of low thyroid function. In Module 5 and Module 12, you can learn more about the importance of blood sugar in thyroid regulation.
Excess estrogen (from external or internal sources) directly inhibits the secretion of thyroid hormones from the gland, which can lead to goiter (enlargement of the thyroid gland). Estrogen also interferes with the function of the liver, including its ability to convert T4 to T3. In Module 17, as well as in our hormonal support guide you can learn more about how the hormonal balance affect your thyroid function.
Beans, lentils, peas, and soy products contain estrogen, especially soy is very estrogenic
Grapefruit contains a chemical that inhibits a liver enzyme, which is needed to detoxify estrogen.
Excessive exercise and psychological or physical stress will increase the stress hormones adrenalin and/or cortisol, which down-regulate the thyroid function by inhibiting the conversion of T4 to T3.
A protein deficiency decreases the liver function, and makes it unable to detoxify estrogen and convert T4 into T3.
The amino acids cysteine, methionine, and tryptophan, which are found in large amounts in muscle meat, inhibit the thyroid function. In Module 5, as well as in our protein guide you can learn more about which proteins are best for your thyroid function.
Manganese and selenium deficiencies interfere with the livers ability to convert T4 to T3, a good source of these minerals is a weakly serving of shellfish.
Nuts, seeds and grains contain polyunsaturated fats as well as amygdalin, which also inhibits the thyroid function.
Excess iodine can block the function of thyroid gland. Iodine should not be taken as a supplement, and salt with iodine should be avoided. The only time to use potassium iodide or kelp is in the case of radioactive exposure danger.
Too little iodine can also create low thyroid function, however it is very uncommon and eating shellfish once per weak will provide the right amount of iodine.
Fluoride is a powerful thyroid suppressor. It is important to avoid drinking fluoridated water and swallowing fluoride containing toothpaste.
Vegetables of the cabbage (cruciferous) family contain enzymes that interfere with the formation of thyroid hormones: Thoroughly cooking destroys most of the anti-thyroid chemicals of cruciferous vegetables.
The cruciferous vegetable family includes among others: broccoli, Brussels sprouts, cabbage, cauliflower, Chinese broccoli, collards, daikon, kale, kohlrabi, mustard greens, mustard seeds, rutabaga, turnip red, radish, watercress, wasabi, etc.

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