Are Cruciferous Vegetables Bad for Thyroid?

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Do Cruciferous Vegetables hurt the Thyroid
Wellness Mama » Blog » Health » Are Cruciferous Vegetables Bad for Thyroid?

“Eat food, not too much, mostly plants.” -Michael Pollan

This is the advice most of us know to be true — that if we eat our veggies, and lots of them, we will be healthier… right?

I always thought so, until I was diagnosed with Hashimoto’s, an autoimmune condition affecting the thyroid. I read a lot of information about how people with thyroid problems should stop eating cruciferous vegetables, such as broccoli, cabbage, or cauliflower.

Unfortunately, these are some of my favorite vegetables! As I dug into the controversy, I found some sources claim that all cruciferous veggies should be avoided, while others say it’s okay to eat them if they’re cooked. I also read that it’s recommended to take a natural iodine supplement to support the thyroid when eating cruciferous veggies.

With all that conflicting information out there, I needed an answer to this question for myself.

I asked my doctor’s opinion on cruciferous vegetables, and his answer (combined with my own independent research) assured me that it’s perfectly safe to consume these vegetables regularly.

Here’s why:

What Are Cruciferous Vegetables?

First, a recap: cruciferous veggies are a hearty group belonging to the mustard family. They’re named for the Latin word Cruciferae that means “cross-bearing.” This term refers to the four petals of leaves on the plant that resemble a cross.

You might know that kale and broccoli are cruciferous veggies, but there are many more beyond those staples. Other cruciferous vegetables include:

  • Arugula
  • Bok choy
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Collard greens
  • Horseradish
  • Mustard greens
  • Radishes
  • Rutabaga
  • Turnips
  • Watercress

These types of veggies are generally very healthy for you (read my post on broccoli sprouts if you need convincing), but you might have heard mixed things about eating them if you have a thyroid disorder.

Here’s a breakdown of why cruciferous vegetables are controversial, and why I think they’re safe to eat anyway.

Why Cruciferous Veggies Are Good For You

In my opinion, cruciferous vegetables represent some of the healthiest foods out there.

Most notably, this class of vegetables are protective against different types of cancer, including breast, lung, colorectal, and prostate cancers. This is all thanks to glucosinolates, a sulfur compound available only in cruciferous veggies. It’s what gives those veggies a pungent, slightly bitter taste.

Plus, cruciferous veggies are packed with health benefits. They’re an excellent source of minerals, like folate and fiber, and vitamins like C, E, and K. They also contain powerful phytochemicals that may help soothe chronic inflammation and reduce the risk of cardiovascular disease.

Too Much of a Good Thing?

The problem with cruciferous veggies is that they contain goitrogens, which are substances that affect the thyroid gland. Specifically, goitrogens mess with the thyroid’s ability to take in the essential mineral iodine. Your body needs it to produce thyroid hormone. If you don’t get enough iodine, it can lead to a bulge in the throat known as goiter.

This is especially problematic for people who already have an underactive thyroid and don’t want to slow it down further.

Cruciferous veggies aren’t the only foods to contain goitrogens. Other goitrogenic foods include:

  • Peaches
  • Peanuts
  • Red wine
  • Soy products
  • Strawberries
  • Sweet potatoes
  • Teas (green, white, oolong varieties in particular)

Peanuts and soy products aside, I wouldn’t go out of your way to avoid goitrogens. The health benefits of the food often far outweigh the negatives. This is because most people have an excess of iodine in their diets and not a deficit.

Why Eating Cruciferous Veggies Is Probably Safe

Despite the presence of goitrogens, I think the benefits of eating cruciferous veggies outweigh the negatives — even if you have thyroid problems.

That’s because you would have to eat enormous amounts of cruciferous vegetables to affect the thyroid. And I’m not sure many of us have the problem of overeating vegetables!

So far, there has only been one case study where too many cruciferous vegetables harmed the thyroid. In this case, an 88-year old woman developed hypothyroidism after eating two to three pounds of raw bok choy every day for several months.

So unless you’re eating several pounds of cruciferous vegetables daily, you are probably in the clear!

But What About Getting Enough Iodine?

Since cruciferous veggies mess with the thyroid’s ability to take in iodine, you might be concerned that your levels are too low. However, in today’s world it is pretty easy to have too much iodine, which can be just as detrimental to the thyroid (and was for me)!

This is especially problematic if there is a deficiency in selenium as well, as selenium can help mitigate the toxic effects of too much iodine in the thyroid.

My doctor Dr. Alan Christianson explained that if a person’s thyroid disorder is not caused by iodine deficiency, the iodine blocking properties of cruciferous vegetables are nothing to worry about (especially if the person is eating a nutrient-dense diet that contains natural sources of iodine and selenium). He estimates that over 90% of thyroid patients are clear of iodine deficiency problems, so cruciferous vegetables are almost always a non-issue.

On the other end of the spectrum, too much iodine can increase your risk of autoimmune disease. This is evidenced by higher rates of autoimmune thyroid disease in Greece after iodine was added to the food supply.

In these cases, the mild iodine inhibition from cruciferous vegetables can actually be helpful for those with thyroid problems.

Plus, cruciferous vegetables may help the body produce glutathione, an antioxidant that can boost thyroid health and fight autoimmune disease.

So in other words, cruciferous veggies might actually be helpful for thyroid disease in many cases!

How I Minimize Goitrogens

If you plan on eating a large amount of cruciferous veggies, such as in the Wahls Protocol, and are concerned about any effects on your thyroid, there are easy ways to reduce the chance of any negative side effects.

1. Cook Your Veggies

If you’re still concerned about goitrogens, just be sure to cook or ferment your veggies instead of eating them raw. This will deactivate most of the goitrogens.

For example, if you drink green smoothies, consider blanching the spinach or kale ahead of time, then freeze until ready to blend.

2. Get Enough Iodine and Selenium

It also helps to make sure you’re getting enough iodine and selenium. Some great selenium-rich foods include:

As for iodine, you don’t need to stick to table salt to get your fill. Try these healthy iodine sources instead:

Personally, I eat a lot of green vegetables daily and consume about 75% of them cooked and only 25% raw. I also make sure that my diet contains natural sources of selenium.

Why I Don’t Recommend Supplementing With Iodine

You might be tempted to add an iodine supplement to your routine so you can safely eat more cruciferous veggies.

However, I don’t suggest trying one. A large intake of iodine can mess reduces the thyroid’s ability to produce hormones.  I learned this the hard way when my chiropractor recommended that I go the supplemental route. I immediately felt worse!

In most cases, it’s best to stick with natural and healthy sources of selenium and iodine while battling a thyroid problem. Pay attention to how your body adjusts to the extra intake of nutrients, and adjust your diet accordingly.

The Bottom Line

Cruciferous vegetables provide a variety of benefits, even (and especially) for those with thyroid disease. Of course, if you or your children are hypothyroid or battling autoimmune disease, you should work closely with a qualified doctor or functional medicine practitioner to find the best diet, medication, and lifestyle to fit your needs.

This article was medically reviewed by Dr. Terry Wahls, a clinical professor of medicine and clinical research and has published over 60 peer-reviewed scientific abstracts, posters, and papers. As always, this is not personal medical advice and we recommend that you talk with your doctor.

Do you suffer from a sluggish thyroid? Do you eat cruciferous veggies? Tell us about your experience in the comments below!

Katie Wells Avatar

About Katie Wells

Katie Wells, CTNC, MCHC, Founder of Wellness Mama and Co-founder of Wellnesse, has a background in research, journalism, and nutrition. As a mom of six, she turned to research and took health into her own hands to find answers to her health problems. is the culmination of her thousands of hours of research and all posts are medically reviewed and verified by the Wellness Mama research team. Katie is also the author of the bestselling books The Wellness Mama Cookbook and The Wellness Mama 5-Step Lifestyle Detox.


53 responses to “Are Cruciferous Vegetables Bad for Thyroid?”

  1. Margaret Meerabux Avatar
    Margaret Meerabux

    I have Hashimotos disease and use an atomic form of iodine called Nascent Iodine. It goes to wherever it is needed in the body within thirty minutes and any that is left over is expelled from the body, so you can’t get too much. I buy it from Rejuve Health in Australia. It is distributed by Environmedica in Austin, Texas. I find it difficult to get the nutrients I need from food as I have intolerance of several food groups. Coconut oil is a disaster for me. I’m told my liver could be the problem. While the thyroid has not got any worse, it seems to be holding steady as a result of the iodine. After trying many diets I’ve settled for trying to keep my immune system in good shape.

  2. Jodi Jacobson Avatar
    Jodi Jacobson

    I see this thread has been inactive for awhile, but thought I’d try a question anyways!
    I have an ulcerative colitis (autoimmune dx) background that is currently very active & also a long hx of hormone imbalance. I’ve found that DIM supplements have helped with this (yay!) however now my doctor is concerned with symptoms of a hypothyroid, which I haven’t had any issues with prior. Any insight on DIM and thyroid function?
    Thank you for any input, have been a long time follower of yours but 1st time posting!

  3. Ken Avatar

    You say: “Most notably, leafy green veggies are protective against different types of cancer, including breast, lung, colorectal, and prostate cancers. This is all thanks to glucosinolates, a sulfur compound available only in cruciferous veggies”

    These two sentences contradict each other just a bit. First one indicates leafy greens in general are protective.
    Second one says the glucosinolates are only in cruciferous, thus leaving out other leafy greens. So that leaves me unsure.
    Can you clarify?

    1. Katie Wells Avatar

      Hi Ken, good catch, the article has been updated to reflect ‘leafy greens’ to say ‘cruciferous’ now. Thanks!

  4. Daniel Avatar

    According to present study thyroid functions improve in hypothyroid patients doing regular physical exercise, as TSH levels decreased, and T3 and T4 increased in regular exercise group. Exercising increases metabolic activity, which helps burn more calories and helps keep weight down.Dec 16, 2015

    1. Daniel Avatar

      Although if your fat and exercise and diets dont work, try making your morning coffee with green tea water ad some spices, use half honey to sugar and at 3 or four drops of hot tabasco source, this taken twice a day, is supposed to help because capsaisin is cause for your fat cells to puke into your blood, so drink lots of water and go toilet often

  5. Daniel Avatar

    After all this stuff about thyroids and whatnot and nobody thinks to mention cardio vascualla exercise to strengthen the lazyness out cos if you eaten right but move like a sloth you aint gonna push your glands into active production and if you dont use it u loose it

  6. Roger Avatar

    What about coffee? My doctor recommended fewer cruciferous vegetable, and also less caffeine…much harder to do without coffee than vegetable…at least for some of us.

  7. Samar Avatar

    I’ve been diagnosed wit Hashimoto for 5 years now ( i have the antibodies too) and i am avoiding Calciferous vegetables since then because of what i read about them, i didn’t cut it all but minimized it and start steam them,
    now with this i will go back to them normally, also i am trying to start your 30 days autoimmune reset, I was fine for the first 2 years and lost around 30 pounds until i gave birth to my baby 3 years ago and i lost control 🙂 I need to loose at least 20 pounds also I start to have hives lately.
    Thank you for sharing all these information.

  8. esteri Avatar

    Would it be a solution to eat seaweed whenever you eat cooked cruciferous to protect the thyroid with a natural form of iodine.

  9. Russell Eaton Avatar
    Russell Eaton

    Cruciferous vegetables should be completely avoided in the human diet for many reasons.
    Whether or not your diet gives you enough iodine, the consumption of cruciferous vegetables as a staple will cause an on-going effect on your thyroid because glucosinolate compounds in cruciferous vegetables will inhibit the thyroid from using what little iodine you receive from the diet. Without sufficient iodine, the thyroid cannot function properly and you’re into hypothyroidism territory.
    In a diet that regularly includes cruciferous vegetables, the goitrogenic effect will be insidious and not obviously perceptible. Even a medical test may show your thyroid to be OK. But the continuous, albeit mild, goitrogenic effect will have an adverse effect on just about every aspect of your health, giving you an under-par quality of life.
    In the case of an underactive thyroid, you cannot treat the condition with iodine supplements because goitrogens (in cruciferous vegetables) will prevent the thyroid from accepting iodine. So however good the diet with respect to iodine, if you consume cruciferous vegetables the thyroid will continue to suffer.
    if you are at all iodine deficient it is particularly important to avoid cruciferous vegetables. The reality is that iodine deficiency is rampant throughout the world.

  10. Veronica Avatar

    Most thyroid conditions are caused by Iodine deficiency. We need to look at the studies, many which were done before we were born. There is so much misinformation on Iodine that it’s adversely affecting people’s health. It’s time to move away from the myths like you can overdose on Iodine. Fact is, the body, if it can, absorb what it needs (excess estrogen blocks absorption of iodine) and expels the rest. Iodized salt is useless and many elderly folks are wrongly told to reduce their intake, when in fact it is the type of salt they are using which should be ditched. Estrogen dominance plays a big role in Iodine deficiency, and blood tests are useless. Only an Iodine loading test (pee) is useful to see how much your body is taking in vs how much you were given. The veggies are not the issue, your broken body is. I encourage you to research. Iodine deficiency, estrogen dominance. There are two experts that discuss this and I am giving you their names because we need to get healthy, and knowledge is power:
    Jorge D. Flechas, M.D., M.P.H. and David Brownstein, M.D.
    They have many informative presentations on youtube

  11. Esteri Avatar

    Would you consider eating 5 grams a day of roasted seaweed snacks a good compromise to balance the possible negative effects of raw cruciferous without taking an iodine supplement. I only use celtic or pink salt so wondering if when I eat raw cruciferous if just having a bit of iodized salt with might be another solution?

    ALso VERY curious to know if you have checked out this thyroid approach:

  12. Roger German Avatar
    Roger German

    Sounds like, if you pick the right research, you can eat just about anything you want, despite research showing the exact opposite. Most research I’ve seen indicates that those with hypothyroidism should limit or avoid cruciferous vegetables. But then, I’m not a fan of cruciferous vegetables, so it works for me.

  13. esteri Avatar

    If raw cruciferous veggies are fermented do you know if that is the same as cooking as far as deactivating the ant thryoid aspect?

  14. Kat Avatar

    I live in a selenium-poor area, so I supplement daily with 100mcg of selenoprecise, which is an organic selenium supplement. That along with zinc orotate has been great for me. My hair was thinning in the middle and it has made a nearly “full” recovery. Has anyone else had any good experience with selenium?

  15. Virginia Avatar

    This article goes against everything I have reasearched and belueve in. You are giving people permission to do the exact oposite of what wd ar supposed to do tohelp our low thyroid. I am undef tge care of my accupuncturist and on a regimine that knclodes selenium 200 mcg and 50mg of iodine/iodide…your thyroid is blocked by toxic halides (floride, bromide etc.)which mimic iodide therefore blocking it. You have to eliminate those toxic copycats before iodine can even start getting to your thyroid. Takes abpit 3 months. Don’t start iodine without knowing how to ease into it.

  16. Marissa Avatar

    This is a great article! I shared it on for you 🙂

  17. Nikki Lynch Avatar
    Nikki Lynch

    I have an under active thyroid gland and have just heard to avoid all cruciferous vegetables. In checking up on line some websites say that spinach is cruciferous and some say it isn’t. Could anyone clarify this as I consume a lot of spinach in my juices and really don’t want to give them up.

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