How They Affect Your health

Goitrogens (derived from the word goiter) or glucosinolates are a plant species in the Cruciferae (Brassicaceae) family.

These plants have a natural defense against predators and fungal attacks. When they are eaten by animals or humans, they inhibit the thyroid gland from functioning correctly. This causes an enlargement and atrophy of the thyroid which creates a goiter.

Individuals who take antithyroid drugs propylthiouracil or methimazole should not eat these food items.

For some people who ingest goitrogens, the results can be felt immediately through a pronounced increase in their thyroid symptoms.

Common Goitrogens

These following foods are considered goitrogenic:

  • African cassava
  • Babassu (palm tree coconut fruit popular in Brazil and Africa
  • Bok choy
  • Broccoli
  • Brussel sprouts
  • Cabbage
  • Canola oil
  • Cauliflower
  • Chinese broccoli
  • Daikon
  • Collards
  • Gluten
  • Kale
  • Kohlrabi
  • Millet
  • Mustard greens
  • Peaches
  • Peanuts
  • Rapeseed oil
  • Radishes
  • Rutabaga
  • Soybean and all soy products including tofu
  • Spinach
  • Strawberries
  • Turnips
  • Watercress

Raw and Excess

These products act as an antithyroid drug by disabling the thyroid function if eaten raw and in excess.

The good news is that the harmful compounds in the plants can be destroyed by thorough cooking  and are lost through leaching into cooking water.

It is not necessary for you to eliminate all of these products because the good often outweights the bad.

Soy is a Goitrogen

Soybeans contain estrogenic plant hormones called isoflavones.

Saponins in soy may also be goitrogens. Unfortunately, cooking and processing methods using heat, pressure and alkaline solutions will do nothing to destroy the isoflavones or saponins completely.

Soy isoflavones can only be partly destroyed by cooking or fermenting.

Fermented, cultured, or aged soybean products such as tempeh, soy sauce, miso, and natto are acceptable if eaten is small portions.

If you are consuming processed foods which contain hydrolyzed soy protein, they are hidden sources of soy isoflavones. These are known disruptors of the thyroid.

For some individuals, there is a mistaken mind set that because soy is considered natural, it should be safe.

That is incorrect thinking.

Soy Research

Research from the FDA's National Center for Toxicological Research (NCTR) in 1997, indicated that isoflavone genistein is a potent inhibitor of Thyroid Peroxidase (TPO).

This compound has proven to be more potent than the common antithyroid drugs.

One serving of soy food provides up to three times more goitrogenic potency than the standard pharmaceuticals for thyroid inhibition.

As early as 1930, medical journals reported enlarged thyroid glands in test animals fed a diet of soybeans.

In the 1950's, reports surfaced indicating that soy formula given to infants produced goiterism.

Dr. Yoshimochi Ishizuki with Aichi Medical University of Japan had healthy volunteers ingest 30 grams of pickled soybeans a day.

There was a marked disruption of the thyroid which became apparent within thirty days.

Even though the test subjects consumed seaweed daily to provide adequate iodine intake, the thyroid health was still compromised.

The report by Dr. Ishizuki indicates that continued exposure to the antithyroid agents in soy results in elevated levels of TSH, even if iodine levels are sufficient.

For more information on how soy is detrimental to your health, go to Soy On Line


If you have healthy thyroid function, the thyroid compensates and makes additional hormones to adjust to the ingestion of toxins.

Dr. David Brownstein, author of "Iodine - Why You Need It and Why You Can't Live Without it", advises that you take more iodine to help compensate for consumption of goitrogenic foods.

The iodine acts as a natural detoxing agent for these toxic agents as well as other toxins lurking in your body such as halogens.

If your thyroid is compromised, the thyroid gland will grow more cells to make up for the inadequate hormone production.

The end result is a goiter and this condition will lead to iodine deficiency.

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