Foods That Can Affect Your Thyroid

All About Goitrogens and Cruciferous Vegetables

Close up of woman chopping vegetables
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Goitrogens are naturally-occurring chemicals found in various foods. Goitrogens have two ways they can affect your thyroid:

  1. Goitrogens can cause a goiter—an enlargement of the thyroid gland.
  2. Goitrogenic foods can act like antithyroid drugs, slowing down your thyroid, and ultimately causing hypothyroidism, an underactive thyroid.

Foods that contain goitrogens are able to disrupt your thyroid's function by inhibiting your body’s ability to use iodine.

Goitrogens can block the process by which iodine becomes the key thyroid hormones thyroxine (T4) and triiodothyronine (T3). They also inhibit the actual release of thyroid hormone by your thyroid gland, and disrupt the peripheral conversion of the thyroid storage hormone T4 (thyroine) into the active thyroid hormone T3 (triiodothyronine).

If you have healthy thyroid function, and adequate levels of iodine and selenium in your diet, your thyroid can for the most part manage a diet that includes goitrogenic foods. In some cases, however, consuming high amounts of goitrogens on a regular basis may have an impact on your thyroid function.

For those with a diagnosed thyroid conditions, the issue of goitrogens is more controversial. 

 

Which Common Foods Have Goitrogenic Ability  

The key goitrogen-rich foods are the vegetables in the cruciferous category. In addition, there are a number of other foods that contain significant amounts of goitrogens.

Some of the more common and potent goitrogens include the following vegetables, fruits, and other types of foods:

  • African cassava
  • Babassu (a palm-tree coconut fruit found in Brazil and Africa)
  • Bok choy
  • Broccoli
  • Broccolini
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Chinese Broccoli
  • Collards
  • Daikon
  • Kale
  • Kohlrabi
  • Millet
  • Mustard
  • Peaches
  • Peanuts
  • Pine nuts
  • Radishes
  • Red Radish
  • Rutabaga
  • Spinach
  • Strawberries
  • Turnips
  • Watercress

Should You Eat Goitrogenic Foods?  

Goitrogenic foods are rich in vitamins and minerals, and most experts do not recommend that anyone--including thyroid patients--avoid eating them. However, there are a few sensible guidelines to consider.

Steaming, cooking, or fermenting can reduce the levels of goitrogens in goitrogenic foods. If you are concerned about exposure to goitrogens, limit the amount of raw goitrogenic foods. 

If you have normal thyroid function, there is no reason not to include goitrogenics food in your diet. Just be careful not to overconsume raw goitrogens. An important note: Raw juicing often features goitrogenic vegetables like cabbage and spinach, and these juices end up providing highly concentrated amounts of goitrogenic chemicals. 

If you are hyperthyroid, a diet rich in goitrogens may help slow down your thyroid.  (But note that any natural approaches to managing hyperthyroidism and Graves' disease should always be overseen by a physician.)

If you are hypothyroid due to thyroid surgery known as thyroidectomy—for example, you're a thyroid cancer survivor, or you've had your thyroid surgically removed due to a goiter or nodules—you don’t need to be particular about goitrogens.

If you are hypothyroid due to radioactive iodine (RAI) treatment for Graves' disease, you don't need to be particular about goitrogens.

If you are hypothyroid and still have a partially functional thyroid—such as with Hashimoto's thyroiditis—be careful not to overconsume large quantities of raw goitrogenic foods. If you are a heavy consumer of cooked goitrogens, however, and have a difficult time balancing your thyroid treatment, you may consider cutting back on the amount of goitrogenic foods in your diet. You may also want to discuss whether you have sufficient iodine and selenium levels with your practitioner, as these minerals can have a protective effect on the thyroid and balance out the thyroid-slowing and goiter-promoting effects of goitrogens.

What About Soy? 

Soy falls into the category of goitrogens, but beyond its goitrogenic properties, it has other abilities as a phytoestrogen to affect your thyroid function and interfere with absorption of your thyroid medication, whether you have a thyroid gland or not. Some experts recommend that thyroid patients don't overdo soy foods and supplements.

Is There a Genetic Distaste for Goitrogens?

Interestingly, researchers at the Monell Chemical Senses Center, a nonprofit research institute that studies the smell, taste, and chemical irritations, have found that a particular genetic makeup can make you predisposed to dislike goitrogenic vegetables. Apparently, a change to a particular genetic taste receptor actually makes some people sensitive to and intensely dislike the compounds found in goitrogenic and cruciferous vegetables that make them slow down the thyroid. 

The experts have theorized that the ability to to detect—and, due to the aversion, avoid—these anti-thyroid chemicals in foods might provide a genetically-based biological advantage to the more than 1 billion people worldwide who have low iodine status, and face increased risk of thyroid disease.

Sources:

Alissa EM, et al. "Iodine deficiency among hypothyroid patients living in Jeddah." Biol Trace Elem Res. 2009 Sep;130(3):193-203. doi: 10.1007/s12011-009-8329-6

Dabbaghmanesh MH, et al. "Persistence of goitre in children post-salt iodization in Islamic Republic of Iran: autoimmune status." East Mediterr Health J. 2009 May-Jun;15(3):584-90. PMID: 19731774

Felker P, el a. "Concentrations of thiocyanate and goitrin in human plasma, their precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism." Nutr Rev. 2016 Apr;74(4):248-58. doi: 10.1093/nutrit/nuv110. PMID: 26946249

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