7 Thyroid-Suppressive Foods to Avoid with Hypothyroidism

By |2020-12-02T07:15:38-08:00December 2nd, 2020|Hypothyroidism, Nutrition|53 Comments
  • foods to avoid with hypothyroidism

Do you really know which foods to avoid with hypothyroidism?

Well, few people get this right.


Because most people (and experts) look at food in completely the wrong way.

It’s easy to get caught up in the details and miss the bigger and more important picture.

This is why so many experts recommend foods that are believed to be healthy for your thyroid while ignoring the overwhelming evidence showing how dangerous they really are.

You see… foods in general have a huge impact on your thyroid health.

And they can affect any part of your thyroid hormone pathway

…from your thyroid gland all the way down to your thyroid hormone cell receptors and even the mitochondria of your cells.

I talk more about your thyroid hormone pathway and how you can overcome your hypothyroidism by fixing it in this post about “How We Overcome Hypothyroidism When All Else Fails”.

Today, however, we’re going to be looking at 7 foods that directly suppress your thyroid gland.

And they all suppress your thyroid gland in one of two ways:

  1. They block the production of thyroid hormone inside your thyroid gland.
  2. They block the release of thyroid hormone from your thyroid gland into your bloodstream.

The important point to remember is this…

You still need to avoid foods that directly suppress your thyroid gland regardless of any benefit you feel they might provide.

Otherwise, it will be like trying to fix a small leak only to flood your entire house.

It doesn’t make sense to solve one problem only to create an even bigger problem in the process.

And this is especially true for this first food to avoid with hypothyroidism.

1. Flaxseed


Flaxseed is a commonly recommended and used dietary supplement today.

It’s most often used for constipation (a common hypothyroid symptom) and touted for many other supposed health benefits.

But what you might not realize is that flaxseed contains very large amounts of lignans and phytoestrogens, making it one of the most estrogenic foods around.

Chemical studies of phytoestrogens and related compounds in dietary supplements: flax and chaparral.


“Flaxseed contains high levels of phytoestrogens.”

This is a big problem for your thyroid as estrogens directly inhibit the proteolytic enzymes that allow your thyroid gland to release thyroid hormone.

So, while it might help your bowels become more regular, you’re still doing a major disservice to your thyroid.

And if you think all those omega fatty acids are helping, then you’re in for treat with this next food too.

2. Polyunsaturated Fats


Polyunsaturated fats (PUFAs) occur naturally in large amounts in many commonly used oils such as:

  • Flaxseed Oil
  • Canola Oil
  • Fish Oil
  • Safflower Oil
  • Corn Oil
  • Vegetable Oil
  • Seed Oils
  • And more…

While these polyunsaturated fats are known to suppress thyroid function at all levels of your thyroid hormone pathway, their direct effects on your thyroid gland are similar to that of estrogen.

As Dr. Raymond Peat describes…

“studies have found that polyunsaturated fats inhibit the proteolytic enzymes involved in the digestion of food, in the removal of clots, in the formation of thyroid hormone, and many other essential physiological processes.”

3. Grapefruit


We often recommend certain fruits for their thyroid protective effects.

In fact, in the 3 Food Triple-Thyroid-Boosting Daily Protocol, I show you one of the most important fruits we use to boost thyroid function.


You can download this daily protocol here.

However, it’s important to note that not all fruits are created equal.

And grapefruit is a perfect example as it contains very high amounts of estrogenic flavonoids that interfere with your liver’s ability to detoxify estrogen.

Inhibition of 17 beta-estradiol metabolism by grapefruit juice in ovariectomized women.


“This study demonstrates that grapefruit juice may alter the metabolic degradation of estrogens, and increase the bioavailable amounts of 17 beta-estradiol and its metabolite estrone”

Many have been led to believe that grapefruit or grapefruit juice is a healthy alternative to other citrus fruits, which is a common mistake.

4. Over-Eating Muscle Meats


While adequate protein is essential for healthy thyroid function, the type of protein can make all the difference.

Muscle meats, for example, tend to be rich in certain thyroid suppressive amino acids such as cysteine.

And research shows that over-eating these amino acids can block the production of thyroid hormone inside your thyroid gland.

Thyroid peroxidase activity is inhibited by amino acids


“some amino acids (cysteine, tryptophan and methionine, 50 microM each) also inhibited the TPO iodide oxidation reaction completely”

But this isn’t to say that you should avoid muscle meats, as a lack of protein is far more thyroid suppressive than an overabundance.

The goal is to balance the muscle meats you eat with other sources of thyroid-supportive protein such as broth or collagen protein which contains little to none of these thyroid-suppressive amino acids.

Forefront Health Collagen Protein Powder

You can learn more about the collagen protein powder we use with our clients by clicking here.

5. Soy


While soy is still often touted as a health food by many, more people are becoming aware of its dangerous effects.

Soy contains very large amounts of isoflavones and phytoestrogens, making it another highly estrogenic food that directly suppresses the thyroid gland.

And in doing so, it can directly block the release of thyroid hormone into your bloodstream.

[The effects on the thyroid gland of soybeans administered experimentally in healthy subjects].


“These findings suggested that excessive soybean ingestion for a certain duration might suppress thyroid function and cause goiters in healthy people, especially elderly subjects.”

As you can see from this study… estrogen’s effects on blocking the thyroid gland is one of the most common causes of goiter (enlarged thyroid gland) today.

6. All Cruciferous Vegetables


Cruciferous vegetables are commonly over-consumed today and can also be extremely thyroid suppressive.

Some common examples of cruciferous vegetables include:

  • Broccoli
  • Cabbage
  • Kale
  • Cauliflower
  • Brussel Sprouts
  • Kohlrabi

And it’s their goitrogens and plant toxins that are well known for their suppressive effects on your thyroid gland, which occur in two ways.

  1. They contain Isothiocyanates and Thiocyanates which make it more difficult for your thyroid gland to absorb the iodine it needs to produce thyroid hormone.
  2. They contain Oxazolidines and Thioureas which directly block the production of thyroid hormone by your thyroid gland.

(Note: This is covered in much more detail in the following post on “3 Reasons Broccoli May Be Dangerous To Your Thyroid”.)

While most people do cook these vegetables, it’s oftentimes not adequate to make them safe.

7. Alcohol


Alcohol is another thyroid suppressive food that doesn’t get the attention it deserves.

While it’s consumed in many forms, and can provide some antioxidant benefits, it also doesn’t take much to raise estrogen levels and suppress your thyroid gland.

All forms of alcohol are quite estrogenic including:

  • Beer
  • Wine
  • Liquor

Alcohol contributes to estrogen dominance and suppresses your thyroid gland in multiple ways:

  1. Contains phytoestrogens.
  2. Promotes the conversion of testosterone to estrogen through aromatization.
  3. Decreases progesterone production while increasing prolactin.

You can find more specific detailed information on how alcohol affects your thyroid in the following post on “What Happens to Your Thyroid After Drinking Alcohol?

So, there you have it.

Those are seven commonly used foods to avoid with hypothyroidism.

While avoiding these foods as much as possible is always recommended (except meats, which do need to be balanced with other appropriate protein sources)…

…avoiding all the thyroid suppressive foods out there is only one part of the solution.

Another big part of the solution is to instead focus on foods that help boost thyroid function while balancing them properly in your diet for optimal thyroid function.

And in the 3 Food Triple-Thyroid-Boosting Daily Protocol, we’ll show you the exact detailed protocol and the three simple foods that can help give your thyroid the boost it needs.


It’s a simple protocol used by each and every one of our clients and it can help you to start feeling calm, clear, and full of energy.

Get more information about the 3 Food Triple-Thyroid-Boosting Daily Protocol here.

If you’re not already using it, then you should get started today and see the difference it can make.

About the Author:

Tom Brimeyer is the founder of Forefront Health and the creator of the popular Hypothyroidism Revolution program series. Specializing in thyroid and metabolism disorders, Tom's work has impacted over 50,000 people spanning more than 60 countries. Tom is also a highly sought after practitioner who runs a successful health consulting practice where he continues to help clients across the globe to take back control of their lives from their devastating health conditions.


  1. Jan Dillard May 12, 2016 at 6:54 am - Reply

    I have avoided these and appreciate learning awhile back from you,Tom. I enjoy your book and use for recipes and my simple syrup. I use gelatin powder daily, for protein. I sleep until I wake, most days. I did eat the things you mentioned before I knew I was hypothyroid. Yes, I enjoy organic coffee, with Great Lakes gelatin, simple syrup and 2% in the morning. Headed to get a cup now!

    You are a great resource. Thank you!!!

  2. Robyn May 12, 2016 at 8:16 am - Reply

    Should someone without a thyroid and who is taking desiccated thyroid also avoid these foods?

    • Tom Brimeyer May 12, 2016 at 12:15 pm - Reply

      Hi Robyn, this article was more in reference to looking at the direct effects on the thyroid gland but many do suppress thyroid function in other ways, i.e. at the liver.

  3. Terri May 12, 2016 at 8:40 am - Reply

    My understanding was that cooked/streamed broccoli and cauliflower are okay but that they should not be eaten raw. Can anyone clarify this?

  4. Folake May 12, 2016 at 8:56 am - Reply

    Same question, am on thyroxine, so should I avoid these foods

    • Tom Brimeyer May 12, 2016 at 12:19 pm - Reply

      Yes, they should be avoided for optimal thyroid function regardless of medication.

  5. jean ivy Maycock May 12, 2016 at 10:41 am - Reply

    ok Robyn,

    This is my area of interest too!! I have just had to have my last bit of thyroid removed due to nodules. I am also vegetarian and wondering if there is a substitute for the bone broth. I am now on Euthyrux. 2 months into treatment.. I must say that the change in diet i.e. orange juice. poached eggs,fried potatoes (In Coconut oil) and medium roast coffee is so far proving to be very effective. Energy levels for the day have improved so much and no bloating, I keep finding what effects me during the day. and eliminating it accordingly The green salad,brocolli, beans and legumes have also proved to have a huge negative effect. So excited about finding out more.

    • Tom Brimeyer May 12, 2016 at 12:21 pm - Reply

      Hi Jean, that’s great to hear!

  6. Romy May 12, 2016 at 11:12 am - Reply

    Thank you Tom. But broccoli when cooked should still be ok? is cancer fighting too.
    And had grapefruit in a smoothie, so that is not good either? :
    best oil is cococut and virgin olive oil?
    Thanks ~

    • Tom Brimeyer May 12, 2016 at 12:16 pm - Reply

      I talk more about the cooking of broccoli in the article referenced on that.Grapefruit wouldn’t be the best for a smoothy. And coconut oil would be preferable.

  7. Romy May 12, 2016 at 11:19 am - Reply

    BTW are those foods the same for Hashimoto?
    thanks !!

    • Tom Brimeyer May 12, 2016 at 12:16 pm - Reply

      Very much so.

  8. karen dubois May 12, 2016 at 9:54 pm - Reply

    Thank you.

  9. Tomasz Niesiolowski May 13, 2016 at 5:08 am - Reply

    I avoid PUFA’s and use only clarified butter and cooconut oil.
    Can I use also cocoa butter in my diet?
    My TSH improving each month: 5.5, 4.7, 3.7 and 2.7 now.

    • Tom Brimeyer May 13, 2016 at 11:58 am - Reply

      Hi Tomasz, you can as it’s predominantly saturated fat with some monounsaturated but very little PUFA.

  10. Ellena Nortje May 13, 2016 at 12:07 pm - Reply

    Hi Tom,
    I have been told to use fish oil and krill for its anti blood clotting benefits and other health benefits like improving mood and joint health. I did not realise they are PUFAs and if I understand you correctly, not only bad for the thyroid but bad for preventing blood clots?

    So hypothyroid people should only use butter and coconut oil?

    Many thanks

    • Tom Brimeyer May 13, 2016 at 12:21 pm - Reply

      Hi Ellena, no that was in reference to the breaking down of clots that already exist.

  11. Jeanne Coyne May 13, 2016 at 1:53 pm - Reply

    I have Hashimotos and now hypothyroid with nodule. I’m also on hormone replacement meds. Should I come off those? I take Armour and am gluten free. Trying to do what I can for thyroid.

    • Tom Brimeyer May 19, 2016 at 9:20 pm - Reply

      Hi Jeanne, those questions depend a lot on your specific case so there’s no general answer that can be given. If this is something you would like to discuss in more detail through a consultation, you can contact support@forefronthealth.com to set that up.

  12. Romy May 13, 2016 at 2:59 pm - Reply

    Hi Tom.. friend asked me how much broccoli per WEEK is permissible? My question too.
    she eat 3x week cup full.
    Thanks much !!

  13. bob May 15, 2016 at 7:50 pm - Reply

    Hi Tom,

    I understand from this article you say to avoid fish oil, which most people have already switched from I would think due to the fish burps, however, what about eating fish itself?

    Also, do you have recommendations on how much animal protein is appropriate and what to eat as alternatives- maybe chia and hemp seeds or almond butter?

    Also, what about organic or grassfed whey protein? I understand finding a clean source may be an issue now too with who knows how much radiation fallout we are still receiving from Fukishima.


  14. Claire May 19, 2016 at 1:37 am - Reply

    Hi tom Iv been drinking the occasional organic apple cider is this an ok form of alcohol?

  15. Sandie Taylor May 19, 2016 at 3:16 am - Reply

    Hi Tom,
    Interesting read and very thought provoking. Would you suggest avoiding these foods even once you are are Levothyroxine? Must understanding was at this point the Thyroid has given up working anyway, so therefore would avoiding these foods still be beneficial?

    • Tom Brimeyer May 19, 2016 at 8:58 pm - Reply

      Hi Sandie, yes and for many reasons. Thyroid medications doesn’t shut down the gland completely but more importantly these foods also suppress thyroid function at other parts of the thyroid hormone pathway, i.e. your liver.

  16. Kathy Egger May 19, 2016 at 12:47 pm - Reply

    I would like to know where to set up an consultation appointment?

  17. Patti May 19, 2016 at 2:17 pm - Reply

    When you say fish oil, you mean an omega supplement? Just want to clarify. I have been taking Green Pastures FCLO for almost a year. Is this sabotaging my thyroid? Also, is parsley considered a cruciferous vegetable? Thank you in advance.

    • Tom Brimeyer May 19, 2016 at 8:56 pm - Reply

      Hi Patti, that’s correct. I’ve written about some of the harmful effects but not all. For example: https://www.forefronthealth.com/fish-oil-and-heart-disease/ I don’t believe parsley is a cruciferous.

      • Patti May 24, 2016 at 11:05 am - Reply

        Thank you so much! I’m sure you can guess that in my journey to be healthy- it is very frustrating to find out that I am sabotaging my own efforts! I really appreciate the information.

  18. sanaya February 13, 2017 at 10:19 pm - Reply


    • Tom Brimeyer April 20, 2017 at 6:27 am - Reply

      Progesterone (not estrogen) should be used to regulate the menstrual cycle.

  19. Tricia April 19, 2017 at 3:48 pm - Reply

    Hi tom … I am quite upset with not being able to take flax seed oil 1 tablespoon a day as really helped my hot flashes from menopause . Only started a month ago as recommended from a friend and it as taken away completely x helped my constipation too
    But recently had my blood done x it’s come back as borderline explains things happening to me but
    Any advice , I’m washed out

  20. Tricia April 19, 2017 at 3:51 pm - Reply

    I’ve been hypothyroid for approximately 20 years
    Menapausall for 4years

  21. Cathleen Vescio April 25, 2017 at 2:52 pm - Reply

    I have read many articles that say that ground flaxseed is great for hashimitoes..ur the only one that says no so??? Misleading

  22. Pupa September 13, 2017 at 9:47 pm - Reply

    I personally think that flaxseed helps. My tsh is normal after consuming those a tablespoon a day

  23. Rich September 28, 2017 at 5:50 am - Reply

    Concerning your Collagen Protein Powder, does it contain any fillers, preservatives, or artificial ingredients?
    Has the product been irradiated? Are any solvents involved in the process? Is there an independent lab or third party inspection of the product? Thank you

    • Tom Brimeyer September 28, 2017 at 10:16 am - Reply

      Hi Rich, you can find most of this information under the various tabs here: https://www.forefronthealth.com/shop/collagen-protein-powder/

      The collagen contains nothing but pure collagen. It contains nothing else, no fillers, preservatives, or any other ingredients. Like all of our materials, it does go through third party testing. It’s not irradiated either. It’s produced using an enzymatic process.

  24. Haven McMaster September 28, 2017 at 7:03 am - Reply

    Hi Tom! I read your complete online book and exercise manual this summer and have abided by it pretty well. I had another scan of my thyroid and no growth and only water filled nodules that come and go. I have taken your words seriously about the diet/no alcohol (maybe two times a month a small drink), have started walking and stopped running, and drink salted orange juice at bedtime. My blood test said I am no longer hypothroid! Also take your supplements.

    Thank you for all you have done. If people stop questioning what you suggest and just do it they will see results.

    • Tom Brimeyer September 28, 2017 at 10:13 am - Reply

      Hi Haven, that’s great to hear and thank you for the kind words.

  25. Farida September 28, 2017 at 7:53 am - Reply

    Том, What can you say about cedar oil?

  26. Jessica Mills September 28, 2017 at 8:16 am - Reply

    Oh my gosh, I’ve been eating tons of kale and grapefruit thinking there was no way it was bad!!!😞
    I can’t thank you enough Tom for what you are doing! Rescuing thousands of people from this terrible, completely misunderstood, condition! Thank you thank you thank you!!!!!

  27. David Portnoy September 28, 2017 at 8:31 am - Reply

    Thanks for the article! Is there a list of foods that are recommended?

  28. Elle September 28, 2017 at 10:34 am - Reply

    How is it possible to get adequate omega 3s without fish oil or flax?

  29. Sandy Taylor September 28, 2017 at 3:46 pm - Reply

    HI Tom, Is one glass of red wine ok? I enjoy one in the evening before supper. I gave it up for almost 3 years but have been trying it again. Thanks, Sandy

  30. Kathy October 3, 2017 at 5:48 pm - Reply

    Is fish sauce ok?

  31. Yvonne October 11, 2018 at 7:55 am - Reply

    Thanks for all of the great information you share, Tom. I’ve been feeling SO much better throughout the past year thanks to your advice.

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