5 Foods that Can Wreck Your Thyroid

I have had thyroid issues on and off throughout my life and have heard that foods can affect your thyroid health. These 5 Foods Could Be affecting thyroid disease.  Are you eating any of them?  What do you think of this list--do you think it's accurate or should anything be taken off or added? I wonder if they would have the same effect on someone with hypothyroidism as with hyperthyroidism.


{Hypothyroidism. It’s a big topic these days. Seems almost everyone has thyroid problems and adrenal fatigue these days .  In fact, I’ll be writing about my own thyroid issues soon, hopefully, and will share some of what I’ve learned. Today, let’s learn about 5 Foods that might be a problem for hypothyroidism.  Are YOU eating these?}

So, you’ve recently found out that you have hypothyroidism.

What you eat can impact your thyroid function—for better or worse.

Your doctor probably won’t tell you about this, but knowing how the foods you put in your body impact your thyroid function is just as important as getting the right tests and getting on the proper dosage of thyroid medication.

5 Foods to Avoid if You Have Hypothyroidism

1. Soy

Soy is everywhere. Soy burgers, soy cheese, soy milk. It isn’t the health food it’s been made out to be, however.

The problematic compound in soy (for your thyroid) are the isoflavones. In fact, a study in the Journal of Clinical Endocrinology and Metabolism reported that researchers fed some subjects 16 mg of soy isoflavones, which is the amount found in the typical vegetarian’s diet,  and others 2 mg soy isoflavones, which is the amount found in most omnivore’s diets. The subjects fed 16 mg were 3 times more likely to cause patients to convert from subclinical hypothyroidism to overt clinical hypothyroidism (Sathyaplan, 2011).

Cooking does not destroy soy isoflavones. Eliminate soy as much as you are able from your diet. 

What about soy formula?

Soy is not a friend of babies. Check out what the researchers in this study found:

Infants fed soy formula are at higher risk for hypothyroidism and for later development of autoimmune thyroid diseases. In humans, goiter has been detected in infants fed soy formula; this is usually reversed by changing to cow milk or iodine-supplemented diets . After the 1960s, manufacturers reportedly began adding iodine to formulas to mitigate thyroid effects.” (Doerge, 2002)

Soy formula should not be your go-to option if you are having difficulties breastfeeding. Watch out, because even formula that isn’t labeled “soy formula” can contain soy. If you are having trouble breastfeeding, be sure to check out these natural ways to increase your breast milk or try some of these lactogenic herbs.

Finding donor milk is also a far superior option to formula as is making your own cow’s milk formula or goat’s milk formula. .

2. Gluten

If you have a thyroid problem and you’re eating wheat or other forms of gluten, you need to stop. Now.

Nearly 90% thyroid disorders are autoimmune in nature (that means that about 90% of all hypothyroid patients have an autoimmune disease).

There is a strong connection between gluten-intolerance and autoimmune thyroiditis. There are even some doctors who are prescribing a gluten-free diet for all of their patients with thyroid disorders. Check out this post to find out more about the thyroid-gluten connection..

3. Cruciferous Vegetables

Broccoli, cauliflower, cabbage, kale, brussels sprouts, radishes, turnips, collard greens… and the list goes on (You can find the complete list of cruciferous vegetables here). Some of my favorite veggies are in this list. But these vegetables can indeed cause problems with your thyroid.

These vegetables are considered to be goitrogenic foods. That is, these are foods that cause an enlargement or goiter of your thyroid. They also slow down the function of the thyroid by making it difficult for your body to use iodine, a necessary building block of thyroid hormones.

Good News: Cooking Helps

Does this mean you need to completely give up some of your favorite vegetables? NO! Yay.

Finally some good news, right :)?

In fact, many of the enzymes in cruciferous vegetables can be partially destroyed by heating foods. So, if you’re going to eat cauliflower, cabbage, or kale – be sure to cook the vegetables before eating them.


4. Fluoridated Water

Until the 1950s, fluoride was prescribed to those suffering from hyperthyroidism as a thyroid inhibitor… and it worked in surprisingly low doses. This may sound strange, but fluoride exacerbates the impact of iodine deficiency. As was discussed earlier, iodine is essential for the body in order to create thyroid hormones (Gas’kov 2005Hong 2001Wang 2001Zhao 1998Xu, 1994).

The National Research Council, put together a 500-page review of fluoride and toxicology. Here’s what they had to say about fluoride’s impact on thyroid disease:

“The effects of fluoride on various aspects of endocrine function should be examined, particularly with respect to a possible role in the development of several diseases or mental states in the United States. Major areas of investigation include . . . thyroid disease (especially in light of decreasing iodine intake by the U.S. population).” (National Research Council, 2006)

There are other studies that are somewhat mixed, but if you’re not avoiding fluoride because of goiterigenic properties there are plenty of other reasons to try to eliminate fluoride from your diet.

How to Get Rid of Fluoride?

• Stop drinking fluoridated water. Check out this comparison of different filtration options: they range from very pricy to very affordable. (Surprisingly, the price is not always indicative of the quality of the filtration system.)

• Stop using fluoridated toothpaste and mouthwash. You can find a number of healthy toothpaste’s you can purchase or recipes to make your own!

• Don’t forget to check your medications. You might be surprised to learn that many common medications are fluorinated. Antidepressants, antacids, arthritis medications, and more contain fluoride. Be sure to check this site to find out if the medication you’re taking is on the list.


5. Processed Foods and Foods Containing Sugar

Sugar and processed foods cause inflammation in the body. Inflammation inhibits T4 to T3 conversion.

Moral of the story: decrease foods that cause inflammation.

Eat plenty of fruits, veggies, free-range eggsgrass-fed meats, and healthy fats.

(Hint: inflammation is just another reason to avoid wheat and other grains.)

For more thyroid information, see the following:

– Why Your Thyroid Test is Wrong-And What to Do About It

– Got Hypothyroidism? 5 Questions You NEED to Ask Your Doctor

Please note  – many of the links in this post are affiliate or referral links. If you click on them and make a purchase, I might make a commission. Your support is oh so appreciated, and it helps keep this free resource up and running – thanks!

This book is a fabulous resource for those with thyroid issues.  Did you know that it’s estimated that 90% or more of those with hypothyroidism have Autoimmune Hashimoto’s?

I devoured this book totally in just a few sittings after getting it.  It’s so full of great information and it’s one of those “keeper” books.

Other books I take out of the library, but “keeper” books are for buying and taking notes in and going back to over and over again.

I met the author this year and she knows what she is talking about.

One of the best books on thyroid health in my opinion.

One of the best books on thyroid health in my opinion.

Please remember: neither Adrienne nor I are doctors, so please do not make changes to your diet, supplements, or exercise program without first consulting with your physician.

So what do you think?
Did you know that all of these foods are problematic for good thyroid health?

Luke-Trisha-150x150Trisha Gilkerson is a homeschooling mom to four crazy boys. She blogs with her awesome hubby Luke at Intoxicated on Life where they talk about faith, homeschooling, and health. They’ve authored the Write Through the Bible curriculum and family Bible Studies and have recently released their first healthy living book – Weeding Out Wheat: A Simple Faith Based Guide. They love connecting with their readers, so be sure to follow them on their blogFacebookTwitterGoogle+, and Pinterest.

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  1. I don’t agree with your claim that the healthiest vegetables interfere with thyroid function. I could not find any real evidence that supports your claim. My Dr also disagrees about this claim as well. were is the actual research and by whom was it done by.

    • Hi Tracy,
      I wanted to make sure you noticed that the recommendation in this post wasn’t to completely eliminate these vegetables, but to make sure that most of the time when you’re eating them to cook them and not eat them raw. In fact, I have hypothyroidism, and I very frequently eat these vegetables cooked and very occasionally will eat them raw. Of course, I don’t think they are one of the worst offenders on the list, but it’s good to be aware that they can contribute to problems if you eat them in great quantities raw.

      Below, I’m listing just a few journal articles that you can check out for further reading on this topic:
      Impact of flavonoids on thyroid function. Food and Chemical Toxicology, Volume 49, Issue 10, October 2011
      Chandra AK et al. Goitrogenic content of Indian cyanogenic plant foods and their in vitro anti-thyroidal activity. Indian J Med Res 2004; 119(5): 180-5.
      Ferreira AC et al. Inhibition of thyroid type 1 deiodinase activity by flavonoids. Food Chem Toxicol 2002; 40(7): 913-917.
      Oregon State University’s Site on Micronutrients: http://lpi.oregonstate.edu/infocenter/foods/cruciferous/

  2. I’m curious as to whether fermented soy products like tempe, miso, and soy sauce cause these same issues. Have you seen any research on this?

    • The Weston A Price Foundation has literature on this. Correct me if I am wrong but I believe that they are saying that a small amount of soy foods such as soy sauce, miso, natto, tofu, etc. as long as they are made in the traditional manner (use them as a guide for this) used in small quantities such as a condiment are fine. They say that this is the way that they are used in traditional Asian diets anyway. Things like soy milk, edammes, textured vegetable protein would have a thyroid antagonizing and hormone disrupting effect. I know from personal experience that about 2 months a breakfast drink that had soy protein in it had may hair falling out and a benign growth developing. My brother drinking the same drink for a few months had a benign growth on his finger removed. In my personal case adding a daily 10,000 iu of Vitamin A (not beta-carotene) to my already established D3 and K2 regime suddenly allowed me to stop taking my 100mcg of T4.

  3. Thank you for this informative article. I do eat cruciferous vegetables but cook them after seeing this information before. Unfortunately I had to give up cole slaw, which I love. The past several years I have been making sauerkraut and am wondering what your opinion is on eating raw cabbage that has been fermented and it’s effect on the thyroid. Thanks!

  4. My mom gave me soy formula – she was told her milk “wasn’t good” so she couldn’t nurse me……..I was the oldest of 5 kids and I find it interesting that she was able to nurse all of the others after me. Hmmm….. I have had allergies and other issues that we have wondered if they could have been impacted by all of the soy I ingested as a baby and now, in our family, we avoid it for all of us. Thank you for posting this.

    • I can say that breastfeeding is HUGE for gut health. I hope to write more about that soon. I am so sorry to hear. I was barely nursed as well and have suffered for it.

  5. Maria Aguilera says:

    Hi, I am interested to do a comparison on all the water filtration systems, specifically to remove as much of fluoride, chemicals, pesticides, heavy metals and all destructive modern day contaminants found in water, but your link takes me to a website under construction. Please provide a better link as I want to purchase the best water filtration system.
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    Maria Aguilera

    • Hi Maria,

      I apologize for the inconvenience, we were undergoing some changes on our site that is why you received the notice when you got there. The site is now back up and you should be able to check out the post on various water filtration methods.

  6. Thanks for this list! Does the breaking down of enzymes in lactofermentation make a difference for cruciferous vegetables? Also, does souring or soaking wheat/spelt/kamut/rye/any other gluten-containing grains in forgetting make any difference in the connection to inflammation?

  7. Nathalie says:

    Hi Trisha. I think of the 5 foods you’ve listed to avoid, I would put processed foods and man-made sweeteners (like HFCS and aspartame) at the top of the list. Not only for those with hypothyroidism, but really anyone. Soy would probably be 2nd on my list, unless it was being used as a condiment (like soy sauce, for example) if it were brewed or fermented in a traditional method. Fluoridated water is definitely next as there is no way to ensure that you’re getting what is considered an “optimal dose” by pro-fluoridationists, and not getting too much. So even if you believe in fluoride (which personally I do not) you could easily be going way over what is considered safe (by the pro-fluoride groups). And again, I think that all 3 of these: processed foods (and man-made sugar), soy (except as a condiment), and fluoride should be avoided as much as possible by anyone. But that’s just my opinion. Good article, Trisha.

  8. I have hyperthyroidism, which is seldom discussed… Do you suppose that if I eat these foods it might actually help to suppress my thyroid?

    • Yes, unfortunately “hyperT” is rarely discussed…I have Graves’ disease and have spent the better part of 3 years fighting western medical practices and researching how to address my autoimmune disease. And yes, eating high levels of cruciferous veggies could have a mild helpful suppressing effect for iodine uptake….though there is much speculation on the validity of them causing issues “hypoT”. There is much research showing the anti-inflammatory effects of these veggies greatly outweigh any minor suppressing effectshttp://www.drfuhrman.com/library/cruciferous_vegetables_and_thyroid.aspx. This author gives good basic highlights of certain elements that can aggrevate thyroid (either side of thyroid issues)….it is actually much more complex and anyone with thyroid issues…should take great care to eat clean, unprocessed, non GMO foods..as well as look at vitamin, mineral deficiencies, gut flora and digestive enzyme balance.
      Lastly, (if you haven’t already found her)…..Elaine Moore’s website is invaluable for hyperthyroid issues.

  9. My Slavic grandmother and her family practically lived on cabbage and never had thyroid problems.

  10. What if you don’t have a thyroid? I had mine completely taken out 8 years ago this month… my dr says im on enough thyroid replacement to handle veggies such as cale, broccoli, etc. raw. Is this not true? I LOVE raw veggies and juice kale daily. (I also love radishes and eat them like candy, daily… had NO idea they are bad for us!) Ugh. Anyway, can you help me figure out if I shouldnt eat these things even without a thyroid in my body please? I am so lost on this topic. Thank you.

    • That’s a very good question. I don’t know. I will see if Trisha can come and chime in. I did just read on one site that you don’t need to be particularly concerned about this if your thyroid has been removed.

    • Hi Wendy,

      Since you don’t have a thyroid, I think you can enjoy all of those raw veggies in abundance. :) You don’t have to worry about those veggies slowing down your thyroid function, since you don’t have one. :)

  11. Wow, cruciferous vegetables! I did not know this! Thanks for the education!