Goitrogenic Foods: Your Thyroid's Worst Enemy?

Photo: Linda N./flickr.

Broccoli, cauliflower and other cruciferous vegetables are brimming with important nutrients, including sulfur and cancer-fighting antioxidants. But are they also your thyroid’s worse enemy as a goitrogenic food?

A goitrogen is any food that could help lead to a goiter. A goiter is a swelling in the neck caused by an enlarged thyroid gland. While goiters are rare in modern times, there's a concern that goitrogenic foods could still impair the thyroid, even if they aren’t causing goiters. By far the most common goitrogenic foods are the vegetables in the cruciferous family. These include broccoli, cauliflower, Brussels sprouts, kale, watercress, arugula, maca, radishes, daikon, turnips, collard greens and bok choy.

Is there any truth to this fear?

Goitrogenic foods can inhibit iodine absorption

In a popular article in the Wise Traditions Journal, Dr. Chris Masterjohn gives an overview of the benefits and disadvantages of cruciferous vegetables. He points out that these vegetables are considered goitrogens because they can inhibit the absorption of iodine, which is essential for good thyroid health. Even more importantly, a serious deficiency of iodine could lead to a goiter. Cruciferous vegetables can also prevent iodine being transferred into a breastfeeding mother’s milk, a concern since iodine is certainly needed for the fast-growing infant.

Steaming cruciferous vegetables until fully cooked will reduce goitrogens by two-thirds, but everyone’s digestive bacteria are slightly different, so the goitrogenic effect of cruciferous vegetables will vary from person to person. Masterjohn's recommendations are to eat moderate amounts of cruciferous vegetables, to cook them fully, and to eat iodine-rich foods, such as seaweed, to help balance out the iodine-blocking properties of goitrogenic foods.

Do you have an iodine deficiency? If not, you probably shouldn’t worry about goitrogens

In her book, "The Paleo Approach," Dr. Sarah Ballantyne takes a good look at this issue. Her book is specifically written to help those with autoimmune diseases, so this was an important topic to cover as there are several autoimmune thyroid disorders to consider (such as Hashimoto’s thyroiditis, or Graves' disease). In her opinion, research does not justify avoiding these foods. She points out that in the absence of an iodine deficiency, there is no current evidence that shows a link between eating cruciferous vegetables and impaired thyroid function. If you do have an iodine deficiency she recommends correcting that problem before you start adding large amounts of cruciferous vegetables to your daily diet, and cooking them when you do.

Cruciferous vegetables shown to support thyroid function and fight cancer

Interestingly enough, Ballantyne points out that some of the substances in cruciferous vegetables have been shown to support certain thyroid functions. And, once again, many studies link this vegetable group to reduced cancer rates, making it an important food group to have in your diet.

Build up thyroid-important nutrients

If you want a healthy thyroid, instead of taking goitrogenic foods out, give your thyroid the nutrients it needs to be healthy. One of the most important is iodine, but also important are iron, selenium, vitamin A, and zinc. You can get all of these in a good diet by including certain foods.

Get rid of 'bad food, good food' thinking

We like to classify our foods as either good or bad. We put our food neatly into categories, with cake in the “bad” category and broccoli in the “good” category. That black-and-white thinking gets confusing when you consider that broccoli could have certain negative effects on some individuals. Instead of putting food into categories, we should instead look at your diet holistically, and aim for a diet that gives you nourishment and is well-rounded.

The goal is to create a diet that is full of thyroid-building nutrients, not simply one that avoids any vegetables that have a remote chance of having a goitrogenic effect on the average person.