Goitrogens – how they affect the Thyroid

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What is a goitrogen?

Goitrogens are substances that cause the thryoid to enlarge forming a “goitre”. They may be foods, pharmaceutical drugs (eg, lithium) or chemicals in environmental pollution.

How do they affect the Thyroid?

They can affect the thyroid’s ability to produce metabolism regulating hormones, by interfering with iodine metabolism. This causes the pituitary gland to release thyroid stimulating hormone which may cause the thyroid to eventually lay down more cells in an effort to increase its production of hormones, leading to an enlarged thyroid or “goitre”.

Should we stop eating Goitrogens?

While it could be a good idea to minimise goitrogens in those who have a thyroid condition it’s not necessary to avoid all of them all of the time. Keeping the foods that are high in goitrogens to a minimum, and also eating them cooked, steamed or fermented, will help reduce exposure to goitrogens.

Also getting enough iodine by eating plenty of iodine rich foods such as; seafood, seaweed, yoghurt, cow’s milk and eggs, will help reduce the impact goitrogens will have on thyroid function.

There are so many wonderful nutrients in these foods, that I wouldn’t advocate cutting them out altogether.

Foods that have a high Goitrogenic effect on the thyroid;

  • Bok Choy
  • Broccoli
  • Brussel sprouts
  • Cabbage (including sauerkraut and kimchi)
  • Cauliflower
  • Kale
  • Kohlrabi
  • Mustard and Mustard greens
  • Radishes
  • Swedes
  • Soy (soy isolates, soy milk and tofu)
  • Turnips

Foods with lower amounts Goitrogenic effect on the thyroid;

  • Almonds (raw)
  • Asparagus
  • Bamboo shoots
  • Cashews (raw)
  • Flaxseeds (linseeds)
  • Peaches
  • Peanuts (raw)
  • Pears
  • Pine Nuts
  • Pumpkin seeds
  • Radishes
  • Spinach
  • Strawberries
  • Sweet Potatoes
  • Walnuts (raw)

Steaming, cooking and fermenting all of these foods reduces goitrogenic substances considerably.