which foods harm your thyroid?

Has your doctor told you that certain foods may impair your thyroid function? Are you unsure which foods those are?

Many of my patients run into the same problem, and so I’ve created a resource for them and for you.

what’s a goitrogen?

Goitrogens are compounds in food that can lead to goiters — swelling of the thyroid gland. This happens when the thyroid doesn’t have enough iodine or enzymes to make sufficient thyroid hormone.

Goiters used to be common before salt manufacturers began adding iodine to salt.

They are less common now, but can still occur when people entirely avoid processed salt or overeat foods that impair thyroid function. Such foods may reduce iodine uptake by the thyoid or inhibit enzymes the body uses to make thyroid hormone.

which foods are goitrogenic?

The most common goitrogenic foods include soy, cruciferous vegetables (including broccoli and kale), cassava, maize, bamboo shoots, sweet potatoes, peanuts, strawberries, sorghum and millet. In most cases, the offending compounds are reduced or eliminated by cooking.

Here’s a list of cruciferous vegetables, also known as brassica vegetables because they are from the Brassicaceae plant family.

Brassicaceae vegetables

  • Cabbage (including Napa or Chinese)
  • Kale
  • Broccoli (including raab, rapini or broccolini)
  • Cauliflower
  • Brussels sprouts
  • Mustard greens
  • Radishes (including daikon)
  • Arugula
  • Collard greens
  • Kohlrabi
  • Turnips (including greens)
  • Bok choi

Some plants in this family are also spices — think watercress, horseradish and wasabi. These are generally less of an issue because they’re too strong to eat in large doses.

should you avoid these foods?

Most of these foods, especially the brassica-family foods, are nutritional powerhouses. Most doctors recommend keeping them in your diet — but doing so safely. That means rotating foods so you’re not eating the same thing every day, and making sure most of these are cooked to reduce their goitrogenic activity. (Here’s my favorite thing to do with kale.)

Can you still have some radishes now and then? Or a raw kale salad? In most cases yes, but do it mindfully. And new research suggests that eating these with some iodine-rich foods may help prevent harm to your thyroid. As always, check in with your doctor to find out what’s best for you.


Read more about eating brassicas safely here.

Want help dialing in your diet? Book your personal appointment here.