Diet and Thyroid

There is not much to worry regarding diet in thyroid disease. Our salt and water is iodinated now and you do not need to take extra iodine.

If you have a goitre, it is advisable to avoid goitrogens:  soybean related foods, cruciferous vegetables such as broccoli, cauliflower, cabbage, etc, they release a compound called goitrin when they’re broken down.

Goitrin can interfere with the synthesis of thyroid hormones and increase the size of the goitre. Other foods not included in these categories – such as peaches, strawberries, peanuts, radish, tofu, spinach and millet — also contain goitrogens in a small amount. Cook foods fully to reduce goitrogens.

Thiocyanates make it harder for the thyroid gland to absorb iodine because they compete with iodine for entry into the gland. 

Thiocyanates weaken the activity of the enzyme thyroid peroxides, which is required to insert iodine into thyroid hormone.  This effect can be greatly reduced by iodine supplementation. Foods that form thiocyanates: Bamboo Shoots, Cassava, Corn, Flax, Sweet potato.

Soy In Your Diet

Soy has a role in the prevention of cancer, cardiovascular diseases, reduction of menopause symptoms, increased bone-mineral and decreased insulin resistance.

However, soy can interrupt the absorption of thyroid drugs so that patients with subclinical hypothyroidism are prone to develop overt hypothyroidism with 16mg/day of soy phytoestrogens.

The isoflavones in soy can lower Thyroid Hormone synthesis. The major soy isoflavone, genistein has estrogenic and goitrogenic activity in conditions of iodine deficiency.

Soy may interfere with how the body produces thyroid hormone. Foods that contain soy include Soy milk, soy sauce, edamame, tofu, miso.

Studies showed a lot of soy product or drink a big glass of soy milk, within one hour of taking a thyroid hormone, it might affect absorption.

Generally, experts recommend that people who have a borderline thyroid — one that’s a little underactive but you’re still trying to preserve thyroid function — do not to consume large amounts of soy every day.