Don’t Kale My Vibe: How Kale and other goitrogens and cruciferous vegetables can negatively affect your thyroid function.


I love it. You love it. Beyonce loves it. What’s not to love? It’s full of cancer-fighting antioxidants, makes your bones stronger, prevents against blood clotting, boosts your immune system, aids with weight loss, acts as an anti-inflammatory, detoxes the body, helps prevent heart disease, gives you great skin, and makes a mean salad.

Amazing, right?

Right. BUT. Kale, along with quite a list of other commonly eaten foods, contain something called goitrogens, and these can actually negatively impact your thyroid health.

What are goitrogens?

Goitrogens are a naturally occurring chemical found in many various foods. Though goitrogens are found in many extremely nutritional foods, they can negatively affect your thyroid function.

Never heard of them? Here is a list of foods with a high concentration of goitrogens:

Cruciferous Vegetables

  • Bok choy
  • Broccoli
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Collard greens
  • Horseradish
  • Kale
  • Kohlrabi
  • Mustard greens
  • Rapeseed
  • Rutabagas
  • Spinach
  • Swedes
  • Turnips

Fruits and starchy plants

  • Bamboo shoots
  • Cassava
  • Corn
  • Lima beans
  • Linseed
  • Millet
  • Peaches
  • Peanuts
  • Pears
  • Pine nuts
  • Strawberries
  • Sweet potatoes

Soy-based foods

  • Tofu
  • Tempeh
  • Edamame
  • Soy milk 

    So how do they affect your thyroid?

    Put simply, when you eat foods containing iodine, your body uses this to begin a process of transforming this iodine into key hormones crucial for thyroid health—the T3 (triiodothyronine) and T4 (thyroxine) hormones. Goitrogens, however, block this process from happening. In addition, they can actually inhibit the thyroid from producing necessary hormones, as well as disrupting the conversion the T4 hormone into T3. They also can increase the size of the thyroid, in an occurrence known as a goiter.

    This doesn’t mean you should cut out foods containing goitrogens completely. By no means! We know all these foods to be extremely nutritious. It does mean, however, that you should watch your intake of foods containing goitrogens. If your diet is extremely high in goitrogen containing foods, chances are it might just be effecting your thyroid function.

    Are there any exceptions?

    Yes! If you have had thyroid surgery (thyroidectomy), for reasons like having had thyroid cancer, or perhaps having your thyroid surgically removed due to a goiter or nodules, then you don’t need to worry about goitrogens. Additionally, don’t worry about goitrogens if you have hypothyroid due to RAI treatment for Graves’ disease. You guys are in the clear!

    Can you help limit the goitrogen levels in food?

    You can help reduce the negative impact of goitrogen containing foods by cooking them. The heat will help break down the myrosinase enzyme, which in turn, reduces goitrogens.

    If you enjoy juicing, you should be especially wary. If you are juicing, you are probably both doing so often, and doing so with highly goitrogenic veggies like spinach and cabbage. You should be aware that you are drinking highly concentrated amounts of goitrogenic chemicals in this mix. If you want to continue juicing and/or making smoothies out of these veggies, try blanching and freezing them, as this will help limit their negative effect on the thyroid.

    To conclude,

    Nearly all of these foods are highly nutritious, and you shouldn’t be worried about eating them in moderation. Just make sure you have variety in your diet, and you’re not eating these foods in excess. If that is what you’re doing now—great! Keep doing what you’re doing. If you’re like me, and have been in a habit of eating about two kale salads a day with items like strawberries being a usual addition to your grocery list, then like me, you’ll probably have to start getting a little more creative with the variety in your meals and the amount of these goitrogen containing foods you are allowing in your daily diet.


    *I am not a medical professional, this study has come from my own research and experience. Consult with your doctor about any health concerns you may have.

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