“I heard that brussel sprouts and broccoli are goitrogens and bad for my thyroid so I shouldn’t eat them. Is this true?” 

This is a question I hear all the time from my thyroid patients, whether they have Hashimoto’s, Graves’, or any other type of thyroid dysfunction.

It’s also a topic where I see some of the most confusing and misleading information online.

So let’s get to the bottom of it!

What are Goitrogens?

GoiterGoitrogens are compounds that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. 

Your thyroid uses iodine to produce hormones that regulate body temperature, metabolism, heart rate, digestion, and more. If goitrogens prevent your thyroid from absorbing and using iodine, it can cause decreased thyroid function.

This triggers the pituitary to release thyroid stimulating hormone (TSH), which promotes the growth of thyroid tissue, eventually leading to a goiter. That’s where the name goitrogens comes from.

The important thing to understand, and what most articles overlook, is that there are different types of goitrogens with very different effects on thyroid health.

Some can cause problems and should be avoided, while others are safe and may actually be beneficial.

The two I want to touch on today are food and environmental goitrogens.

Food Goitrogens: The Good Guys

Food Goitrogens
The most common food goitrogens include:

  • Broccoli
  • Kale
  • Brussel Sprouts
  • Cassava
  • Cabbage
  • Cauliflower
  • Soy
  • Turnips
  • Sweet potatoes

Notice that these foods are incredibly nutrient-dense and packed with important antioxidants and phytonutrients. These are not foods you want to avoid unless you absolutely have to!

Yet many practitioners recommend that thyroid patients avoid them because of their goitrogenic status. This belief stems from scientists observing that rabbits who ate very large amounts of fresh cabbage developed enlarged thyroids. 

Important note, humans are not rabbits.

There is far less convincing evidence that human thyroid function is significantly impacted by goitrogenic foods, particularly if you have adequate iodine consumption.

However, there is considerable research showing that many goitrogenic foods improve health.

A recent study evaluated cruciferous vegetable intake and found cassava consumption significantly decreased the risk for thyroid cancer. Cruciferous vegetables were also shown to release compounds after digestion which activated glutathione S-transferase (GST) which helps reduce oxidative stress. 

So can goitrogenic foods impact thyroid health? I am sure they could in extremely high amounts. But, we have to take a common-sense approach and weigh the risks against the benefits. 

In my opinion, the benefits are far greater, especially when you consider the impact on glutathione, your body’s master antioxidant.

If you have a thyroid condition and are concerned about the goitrogenic effects of food, there are two steps you can take to minimize any negative impact while still reaping their nutritional benefits:

  1. Maintain sufficient iodine. The majority of Americans already consume plenty of iodine from iodized table salt. However, you can increase iodine by eating seaweed, saltwater fish, and shellfish.


  2. Eat cooked goitrogenic foods. Cooking veggies like broccoli, kale, and brussel sprouts reduces their goitrogenic properties.

Environmental Goitrogens: The Bad Guys

Now environmental goitrogens are a whole different ballgame. There is plenty of evidence that shows these guys have detrimental effects on your thyroid and absolutely need to be avoided.

Here are a few common environmental goitrogenic and their impact on thyroid function.

  • Perchlorates (which are used in rocket fuel) are found in our soil and water supply and interfere with iodine uptake.


  • Lithium, which is found in our environment and used as a psychiatric drug, can block iodine transport into your thyroid gland.


  • BPA or Bisphenol-A from plastics has a direct action on thyroid hormone receptors.


  • UV filters in cosmetics meant to protect your skin from sun exposure can also alter thyroid balance.


  • Heavy metals like cadmium and lead are known to affect thyroid function and are found in everything from old paint and water pipes to cosmetics to cigarettes.


  • Smoking has been found to be related to the prevalence of thyroid antibodies.


These are things everyone should avoid, but especially if you have a thyroid problem.

Lastly, certain pharmaceutical goitrogens can also interfere with thyroid function, including amiodarone, ketoconazole, sulfonylureas, and sulfonamides.

I hope this helps clear things up and empowers you to make a more informed decision about goitrogens and your thyroid.

If you’re ready to optimize your thyroid function and reclaim optimal health with a personalized treatment protocol based on your history, challenges, and goals, check out our Adaptation Program.

About the Author: Dr. Seth Osgood is a Doctor of Nursing Practice, Board Certified Family Nurse Practitioner and Institute of Functional Medicine (IFM) Certified Practitioner. Dr. Osgood received his post-graduate training in Functional Medicine through the IFM and from working with Dr. Amy Myers. He has helped people from around the world improve their health utilizing a Functional Medicine approach.

Want to work with Dr. Osgood and the GrassRoots team? Become a patient in our West Lebanon, New Hampshire Functional Medicine clinic, our Burlington, Vermont Functional Medicine clinic, or our Austin, Texas Functional Medicine clinic!