Quick Notes

• Goitrogens are substances which interfere with thyroid function
• They can work on the thyroid gland or the hormones themselves
• Certain otherwise healthy foods can act as goitrogens, so anyone with low functioning thyroid function may want to be weary

Thyroid Function

Proper thyroid gland function and hormone metabolism is key for optimal health. Those suffering from Hashimoto's Thyroiditis have autoimmune destruction, but we must also focus on thyroid hormone metabolism. For a complete review please click here.

What are Goitrogens

Goitrogens are agents found in the environment that are known to interfere with thyroid gland function. There are strictly environmental factors (such at chemicals, medications and more) in addition to dietary sources of goitrogens [1].

Goitrogens work by interfering with iodine utilization by the thyroid gland. We call goitrogens - goitrogens- because these compounds may be responsible for the development of a physical goiter. About 5% of the world's population have goiters, many of which are from underdeveloped nations. However, more than 150 million individuals worldwide with goiter live in highly developed countries, despite iodine prophylaxis [2].

Goitrogens work by [2]:

• Directly working on the thyroid gland
• Indirectly by alternating regulatory mechanism of the thyroid gland and the peripheral metabolism and excretion of thyroid hormones [2]

Goitrogens Found in the Diet

Cassava, lima beans, linseed sorghum, sweet potato

• Contain cyanogenic glucosides; they are metabolized to thiocyanates that compete with iodine for thyroidal uptake [3]

Cruciferous vegetables: cabbage, kale, cauliflower, broccoli, turnips, rapeseed

• Contains glucosinolates; metabolites compete with iodine for thyroidal uptake [3]

Soy and soybean products

• Flavonoids impair thyroid peroxidase activity [3]
• Soy or soy enriched foods can aggravate thyroid problems reducing T4 absorption and interfering with thyroid hormone action [4]
• Evidence of goiter growing in infants (10-month) being fed soybean products right from birth (versus breast milk or formula). To reverse stop soybean and add Lugol's iodine drops [4]
• Review of 14 trials: soya protein and isoflavones do not affect normal thyroid function in people with sufficient iodine intake, but they may interfere with absorption of synthetic thyroid hormone (Synthroid), increasing the dose of medication in hypothyroid patients [4]

Cyanogenic Plant Foods: Cauliflower, cabbage, mustard, turnip, radish, bamboo shoot, cassava

• Raw, boiled, cooked extracts of certain plant foods are shown to posses anti-TPO activity [4]
• Boiled extracts of these plant foods showed highest anti-TPO potency, followed by cooked and raw [4]

Millet

• Rat studies: millet containing diets produce effects resembling small doses of anti-thyroid drug methimazole [2]