Goitrogens are compounds naturally present in certain plants. Animal studies suggest that these foods may interfere with the absorption of iodine, which is essential for thyroid function.
Without enough iodine, the pituitary gland releases thyroid stimulating hormone (TSH) and promotes the growth of thyroid tissue, which eventually leads to an enlarged gland, or goiter. If the goiter gets bigger, it can interfere with the windpipe and esophagus and cause coughing or swallowing and difficulty breathing. However, any substance that interferes with thyroid function is of concern for patients with thyroid autoimmune diseases such as Hashimoto’s thyroiditis and Graves disease who already struggle with the production of thyroid hormones.
Which plants are goitrogenic?
Several animal studies show that the following raw cruciferous vegetables affect iodine intake and thyroid metabolism:
· Brussels sprouts
Mustard and mustard leaves
Soybeans and soy products
What does this mean for thyroid patients?
You’ve probably read this list and thought, “Why can’t I eat these foods when they’re supposed to be good for me?” And rightly so. After all, many of these foods are rich in nutrients essential for good health.
The limited research done so far does not suggest that consuming reasonable amounts of these foods inhibits thyroid activity. However, a diet that relies heavily on goitrogenic foods could negatively affect patients with autoimmune thyroid disorders.
A diet geared towards optimal thyroid function makes more sense, rather than a large elimination of all of these foods. At this point, no human studies confirm that cruciferous vegetables cause impaired thyroid function.
Fifty years of research by Dr. Joel Fuhrman suggests that these are not “bad” foods. They may not be the right foods for some people. He states that “cruciferous vegetables could only be detrimental to thyroid function if there is iodine deficiency or insufficient iodine intake,” and may not cause any problems at all if eaten in reasonable amounts.
How much can I eat?
Unfortunately, there is no simple answer to this question since every patient is different. However, in the functional model of care, it is possible to work with your practitioner to find out what is best for you.
As a general rule, most patients with thyroid conditions can tolerate one or two servings of raw goitrogenic foods each day without any problems. Others may need to steam their vegetables to reduce goitrogenic activity.
If a patient wishes to include soy in their diet, fermented soy is preferable, but some evidence suggests that soy and soy products may interfere with the absorption of thyroid drugs in hypothyroid patients. Patients should not rely too much on soy in their diet because it is goitrogenic.
Eating a few servings of these foods a day shouldn’t be a problem, even if you have Hashimoto’s thyroiditis or Graves’ disease. However, they do affect iodine metabolism and if you already have iodine deficiency it increases the risk.
Although cooking these foods can decrease goitrogenic activity, avoid eating too much of these foods. Discuss your concerns with your practitioner and work with them to create a diet that works best for you.