The Worst Food for Your Thyroid (and Doctors Claim It’s “Essential” to Your Health)

By |2021-03-31T06:00:41-07:00March 31st, 2021|Hypothyroidism, Nutrition|38 Comments
  • worst food thyroid

Are you eating the absolute worst food for your thyroid?

Whether you realize it or not, you most likely are.

In fact, 99% of people today, hypothyroid or not, are currently consuming this food (in one form or another) daily without realizing that they are sabotaging their own thyroid health.


For starters, it’s hidden in almost everything you eat.

But here’s the real kicker.

Doctors, nutritionists, and even other health “experts” will tell you that this food is “essential” to your health.

How wrong could they be?

Now, Dr. Raymond Peat has been outspoken regarding the dangers of this food for decades.

However, I never realized just how dangerous it was until I began to look at the research, a little of which I’m about to share with you in just a second.

The reason this type of food is so devastating to your thyroid is because it blocks your thyroid function at all five levels of your Thyroid Hormone Pathway.

Take a look at the infographic below:


This infographic shows all five levels of your Thyroid Hormone Pathway.

Here are the full effects that this type of food has on your thyroid function:

  1. Blocks your thyroid gland from releasing thyroid hormone.
  2. Blocks your thyroid hormone transport proteins from carrying and delivering thyroid hormone to your cells.
  3. Blocks your liver from converting T4 thyroid hormone into the active T3 thyroid hormone that your cells need.
  4. Blocks your active T3 thyroid hormone from binding to your thyroid hormone cell receptors.
  5. Blocks your cells from being able to metabolize/use active T3 thyroid hormone.

This is extremely important to understand because… all of these blockages prevent you from getting active T3 thyroid hormone to your cells, and prevents your cells from using what little active T3 thyroid hormone they do have available.

And as I always say…

If you can’t get thyroid hormone to your cells, or your cells can’t use thyroid hormone, then it doesn’t matter how much thyroid medication you use… you’ll always be hypothyroid.”

So, what exactly is this dangerous food?

It’s actually a subset of fats called polyunsaturated fats, or PUFAs for short.

Some of these fats are oftentimes referred to as “Essential Fatty Acids” (EFAs) because they were once believed to be essential in the human diet.

Yet, they are NOT essential at all, even though they are still named such.

In fact, many research studies have shown that these fats contribute to a number of health issues and diseases, including hypothyroidism.

I’m going to show you exactly how these PUFAs are sabotaging your thyroid health and what you can do help save your thyroid.

1. PUFAs Block Your Thyroid Gland

Your body depends on enzymes, called proteolytic enzymes, needed to release the stored thyroid hormone within your gland into your bloodstream.

Studies, such as the one below, have shown that PUFAs can strongly inhibit various proteolytic enzymes, thereby directly blocking your thyroid gland from releasing the thyroid hormone you need.

PUFAs, along with excess estrogen, are two common causes of low T4 levels found during routine thyroid lab testing.

Inhibition of chymase activity by phosphoglycerides.

“Phosphatidic acid containing an unsaturated fatty acid, such as dioleoyl phosphatidic acid, caused the same extent of inhibition as natural phosphatidic acid from bovine brain, but was 20 times more inhibitory than phosphatidic acid containing a saturated fatty acid, such as distearoyl phosphatidic acid.”

2. PUFAs Block Your Thyroid Hormone Transport Proteins

Once thyroid hormone is released from your thyroid gland, it must be transported to various places in your body by certain thyroid hormone transport proteins.

Studies, including the one below, have shown that PUFAs directly block these transport proteins from carrying and delivering both T4 and T3 thyroid hormones to your cells.

This means that not only can’t you delivery active T3 thyroid hormone to your cells, you can’t deliver adequate inactive T4 thyroid hormone to your liver to be converted into the active T3 thyroid hormone that your cells need.

Effect of long-chain fatty acids on the binding of thyroxine and triiodothyronine to human thyroxine-binding globulin.

“The results indicate that the unsaturated long-chain fatty acids are potent inhibitors of thyroxine binding to thyroxine-binding globulin, whereas the saturated fatty acids have little or no effect on thyroxine binding.”

3. PUFAs Block Your Conversion of T4 into Active T3 Thyroid Hormone

If your thyroid gland can release adequate T4 thyroid hormone, and your transport proteins can deliver that thyroid hormone to your liver, your liver must still convert that T4 into the active T3 thyroid.

In order for your liver to perform this conversion, it requires another enzyme called deiodinase enzyme.

Yet, studies have shown that PUFAs strongly inhibit this enzyme, directly blocking the conversion of thyroid hormone in your liver.

This is a common cause for low T3 levels, even when T4 levels are adequate, on routine thyroid lab testing.

Evidence for an inhibitor of extrathyroidal conversion of thyroxine to 3,5,3′-triiodothyronine in sera of patients with nonthyroidal illnesses.

“Doses (in micromoles) causing 50% inhibition in different experiments varied between 0.2-0.52 for arachidonic acid, 0.3-0.56 for linolenic acid, 0.38-0.40 for linoleic acid, and 0.8-0.9 for oleic acid. Other lipids had less or no inhibitory activity.”

4. PUFAs Block Your Thyroid Hormone Cell Receptors

Once your liver converts your thyroid hormone into the active T3 form, transport proteins must carry that T3 to your cells.

As we’ve already established, PUFAs directly block these transport proteins.

However, what little active T3 thyroid hormone that does get transported to your cells still needs to bind to the thyroid hormone cell receptors of those cells for your cells to use it.

And research shows that PUFAs also block the binding of your active T3 thyroid hormone to these cell receptors.

Inhibition of nuclear T3 binding by fatty acids.

“Unsaturated fatty acids were potent inhibitors of the binding of [125I] T3…”

5. PUFAs Block Your Metabolism and Energy Production

We talk a lot about basal body temperature and how it is directly correlated with your thyroid health.

This is why we use it to assess your thyroid function, far more accurately than blood tests today.

(Note: Learn exactly how to test your own thyroid using our free Ultimate Thyroid Testing Protocol. Get it by clicking here.)

But, what’s important to understand is that anything that blocks your metabolism and lowers your basal metabolic rate negatively affects your thyroid health.

And research has shown that PUFAs, or “Essential Fatty Acids”, do just that. They block your metabolism.

Avoiding PUFAs alone has been shown to increase metabolism significantly.

The effect of essential fatty acid deficiency on basal respiration and function of liver mitochondria in rats.

“Basal respiration in relation to the body weight is significantly increased by EFA deficiency;”

So, as you can see, PUFAs are the worst food for your thyroid as they are involved in directly blocking your thyroid function at every single level.

But…what exactly are PUFAs and how can you protect yourself from them?

4 Simply Ways to Protect Yourself from Thyroid-Suppressive PUFAs

1. Avoid Liquid Cooking Oils and Dressings

PUFAs are found most dangerously concentrated in their oil form, for example:

  • Vegetable Oil
  • Soybean Oil
  • Canola Oil
  • Sunflower Oil
  • Peanut Oil
  • Safflower Oil
  • Corn Oil
  • And more…

(NOTE: Want to know even more thyroid-suppressive oils you need to avoid? Take a look at this article on the “15 Worst Cooking Oils for Your Thyroid“.)

One way to tell if an oil is highly “unsaturated” is that it will be liquid at room temperature or below.

So, if you put an oil in your refrigerator and it doesn’t solidify, then you should toss it in the garbage where it belongs, unless you plan to use it for non-dietary purposes (PUFAs were originally used as a paint base).

And this goes for other foods and products that contain these oils, such as salad dressings.

The only exception is olive oil, which still contains PUFA, but also contains vitamin E, which provides some protection from the PUFAs negative effects.

2. Avoid Eating Packaged Foods

Because PUFA oils are so cheap, they are used widely in packaged foods, most commonly vegetable oil or soybean oil.

Although they may be easier to prepare, packaged foods are almost always harmful to your thyroid.

And don’t be fooled by “health claims” on package labeling.

Aside from being promoted as “essential” to your health, PUFAs are also still being promoted for their supposed heart health benefits, even though they have been shown to increase your risk of heart disease.

In most cases, if the packaging states various health benefits, it’s likely unhealthy for you and your thyroid health.

3. Limit Eating Out and Use Vitamin E

For many of the same reasons as avoiding packaged foods, you’ll want to limit how often you eat out at restaurants as well.

Restaurants use almost exclusively PUFAs for cooking their foods because they are so cheap.

And the cheaper your meal, the more profit restaurants make.

If you do eat out, it’s best to request your food grilled, and without the use of oil.

But it’s still impossible to avoid all PUFAs outside your home.

So, it’s still best to protect yourself as much as possible.

You can do this by using a high-quality pure Vitamin E supplement, such as our Forefront Health Vitamin E Complex.
Learn More About Thyro-Protect Vitamin E

We use this with all of our clients.

But be careful. Most vitamin E supplements are thinned with PUFA oils, which defeats the entire purpose.

4. Protect Yourself with Saturated Fats

Avoiding PUFAs is extremely important in restoring thyroid function.

However, avoiding them is only half the battle.

The other half is protecting yourself by replacing those thyroid-suppressive PUFAs with thyroid-supportive saturated fats, like coconut oil and/or butter.

Ridding Your Body of PUFAs Takes Time (Up to 3 Years)

Even if you remove almost all PUFAs from your diet today you can’t expect immediate results.

The PUFAs you have already eaten have become stored directly in your fat cells.

And the half-life of fat cells is rather long.

As Dr. Raymond Peat points out, it can take up to a year to rid your fat cells of the majority of PUFAs they are currently storing, and up the three years to rid them from the fats stores in your brain.

Although it will take time, the health benefits of ridding yourself of PUFAs are huge.

I highly advise you use all of the recommendations above for protecting yourself against PUFAs.

And while avoiding PUFAs is essential for overcoming your hypothyroidism by unblocking your entire Thyroid Hormone Pathway, there’s still a lot more you can do to help yourself.

There are other factors that are blocking your Thyroid Hormone Pathway too.

And in the 3 Food Triple-Thyroid-Boosting Daily Protocol, we’ll show you exactly how you can start using your diet to further unblock your Thyroid Hormone Pathway and fix some of the other many underlying causes of your hypothyroidism.

Want to overcome your hypothyroidism or Hashimoto’s thyroiditis?

This daily protocol is the easiest way to get started.

It’s based on real science and research, it has been tested and proven by thousands of hypothyroidism sufferers, and it just works, which you will see for yourself.

Click here to learn more about the 3 Food Triple-Thyroid Boosting Daily Protocol.

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. Tatia Veltkamp June 3, 2016 at 6:49 am - Reply

    Wow! Three years to get rid of the PUFAs! Thanks for sharing this article. It helps me to see things like this to guage my patience in healing.

  2. Kim Grover June 3, 2016 at 7:59 am - Reply

    Does this also count when you use oils in home-made lotions and body scrubs? I know they say everything you put on your body gets absorbed into your bloodstream. Alot of recipes call for almond oil, grapeseed oil and mango butter

    • Tom Brimeyer June 3, 2016 at 8:25 am - Reply

      Hi Kim, yes those oils are absorbed through the skin as well. So, it’s best to avoid them in skin care products too.

  3. Sherry L Johnson June 3, 2016 at 8:51 am - Reply

    I use a Eye Makeup Remover that only contains Organic Coconut and Jojoba Oil by Desert Essence, would that also be Thyroid blocking???

  4. Diana June 3, 2016 at 10:48 am - Reply

    Why does it block it in some people but not others?

    • Tom Brimeyer June 3, 2016 at 10:59 am - Reply

      Hi Diana, it’s suppressive in all cases.

  5. Jackie Moore June 3, 2016 at 12:22 pm - Reply

    Does this apply to a Hyperthyroid condition? Should a person who had an episode of the thyroid pumping out too much hormone and causing the heart to race (Pulse at 200), change to the coconut oil and butter?

    Jackie Moore

  6. Kelley Doerfler June 3, 2016 at 12:29 pm - Reply

    What about flax oil? Good or bad?

  7. Mindy June 3, 2016 at 4:00 pm - Reply

    I’m wondering about that stubborn fat that seems to get stuck and stay as we age. Very unsightly, deposited in little areas around the body. But I’m more concerned about the extra toxic load they hold.
    Back in my 20’s – for years I consumed a ton of safflower oil margarine thinking I was doing myself a big favor. I’ve been able to avoid PUFA’s for a few years now.
    Tom, I can’t help but wonder if I might benefit even more from a little micro liposuction at some of the spots since it sounds like they are likely still holding these PUFA toxins.
    It may help my circulation even more.
    I’ve never had any lipo before nor any fat removal therapy and I’m not the type to obsess over what should be a naturally attractive healthy round female figure. Please understand I am not afraid of healthy fat. I just want to know what you think of that idea, or if you know of a better way to dissolve that stubborn, toxic fat without it having to go back through the body systems.
    Thanks for your always well written articles – so deeply helpful !

    • Tom Brimeyer June 6, 2016 at 3:48 pm - Reply

      Hi Mindy, I would think that the stress that the liposuction would place on your body would outweigh the dangers of the stored fats. They aren’t so dangerous when stored, but are quite dangerous in the bloodstream. This is why we work to detoxify them slowly.

  8. Sandy Tayor June 4, 2016 at 8:42 am - Reply

    So basically only use coconut oil is the best choice.

  9. Joe June 4, 2016 at 3:21 pm - Reply

    I like your articles, and think that Ray Peat makes a lot of sense… but I’m not so sure about this. The studies are interesting, but they are in vitro rat studies, so I question how much they actually apply to humans.

    There is also a school of thought that says PUFAs, especially Omega 3s may actually increase sensitivity to thyroid hormone, so production is lowered as a result – much like increased insulin sensitivity results in lower serum insulin.

    Another big question is about the source of the fats in the studies – were they refined and oxidized? And how did they effect vitamin E status? Again, only an animal study – but this highlights the potential difference between oxidized and non-oxidized fats on thyroid conversion:

    Personally, I avoid those processed omega 6 oils like the plague…I stick to olive and coconut oil. But I still get a bit of PUFAs from nuts and seeds, including flax. Maybe I’ll change when some human studies come along…

    • Tom Brimeyer June 6, 2016 at 3:30 pm - Reply

      Hi Joe, I too wish there were human studies available for everything, but unfortunately that’s not the case. But they use rats for a reason as well. Keep in mind that whether or not PUFAs are oxidized prior to consumption, they will still oxidize within the body as oxygen and body heat are both readily available within the body. I think the studies mentioned provide adequate evidence against the thyroid hormone sensitivity theory.

    • Tom Brimeyer June 6, 2016 at 3:42 pm - Reply

      Also wanted to mention some other points that you might find helpful that are related directly to human studies. For example, hypothyroidism is far more common among women than men and women show much higher concentrations of omega 3’s in their tissue (,,

  10. Joanna Seib June 4, 2016 at 3:29 pm - Reply

    Do we need omega 3? It is supposed to be anti-inflommatory and very important for the brain?

  11. Illa Garcia June 5, 2016 at 9:09 pm - Reply

    My thyroid goes into hyper drive. It causes my body to eat itself. My metabolism rate is high. Has been all my life. Now I can’t seem to gain weight or keep any on.

  12. John June 6, 2016 at 4:40 pm - Reply

    Maybe I missed it, but I don’t see where you answered the question about coconut oil – it thickens below room temp, but I thought it was one of the few good oils?

    • Tom Brimeyer June 6, 2016 at 4:56 pm - Reply

      Hi John, yes, coconut oil was discussed in the article.

  13. Rachelle Delcambre June 6, 2016 at 5:17 pm - Reply

    Hi Tom, What is your opinion of avocado oil?

    • Tom Brimeyer June 7, 2016 at 7:27 am - Reply

      Hi Rachelle, it’s very unsaturated which is not desirable and studies have suggested that it is toxic to the liver.

  14. Heather June 8, 2016 at 3:56 pm - Reply

    Tom, what about liquid MCT coconut oil?

    • Tom Brimeyer June 9, 2016 at 9:11 am - Reply

      There’s nothing wrong with MCT oil.

  15. Sandy Taylor June 10, 2016 at 6:40 pm - Reply

    With hypothyroid and hashimoto’s my LDL is elevated. Is there any Omega 3 that will be safe for me to take to try and lower the number. I have also been told Niacin ir red rice yeast would help. What are your thoughts. I do not want to take something that might make my condition worse.

  16. John June 24, 2016 at 4:33 am - Reply

    If this is true about Omega-3 fish oil, which I have been taking and pushing on people for years, then I’ve almost seen everything. And indeed, it does seem my low thyroid issue may be worse, though there are numerous other possible causes.

  17. John June 24, 2016 at 9:52 pm - Reply

    There are two protein powders I want to be able to take, both are considered among the best natural Whey proteins with simple ingredient lists and no artificial sweeteners. One is the BodyLogix brand, and the other is the Optimum Nutrition Gold Standard Naturally Flavored. I have three concerns about them:

    1. They both contain lecithin. No doubt it’s not a huge amount, but wouldn’t that be the kind of PUFA we need to avoid?

    2. Are these good protein sources for Hypothyroid sufferers? It seems to me that even though they are not “bone broth” powders, they might still be very good.

    3. The Optimum Nutrition version has some regular sugar in the ingredients, but BodyLogix is stevia sweetened. I know you said that sometimes even sucrose is beneficial for Hypothyroid sufferers re the sugar craving or need for carb issue. However, what about the statements out there that sugar causes inflammation? Wouldn’t it really be preferable to avoid sugar (sucrose) normally except when it is not practical to do so because of issues like that?

    I already have the BodyLogix Vanilla Whey Concentrate and am almost finished with it.

  18. Mayda Alonzo July 17, 2016 at 12:36 am - Reply

    I’m a very confused woman because Dr remove my thyroid for cancer they gave me radiation iodine
    pill in 2000, so now after 16 years I’m feel like a suffer from hypothyroidism I have the same symptoms the
    many people has thyroid. I don’t have any idea whish food is bad or good for me. Because my problem is identical like a I has but I don’t have de thyroid. Please Help me.

  19. Kate August 27, 2016 at 4:48 pm - Reply

    I would appreciate your comments on John’s question about lecithin in protein powders. I make my own liposomal Vit C with lecithin powder. If you feel this is no good, please could you recommend an alternative.
    Many thanks for your wonderful work.

    • Tom Brimeyer August 29, 2016 at 10:14 am - Reply

      Hi Kate, I might be more concerned over the vitamin C. Vitamin C used in food preservation and supplements is a common source of heavy metals. There are much healthier ways to get more than adequate vitamin C. As for the liposomal, it depends on the type of lecithin used. Soy lecithin should be avoided as it has been shown to be quite estrogenic.

  20. ssur November 23, 2016 at 8:41 am - Reply

    very very nice.

  21. Vesna Stupar January 24, 2017 at 3:54 pm - Reply

    Hi, Tom, please tell me whether the famous Italian grape-seed oil is OK for hypothyroid patients? I am usng it for years for cooking 😊

  22. Tasha July 7, 2017 at 7:49 am - Reply

    Hi! What is the Vitamin E derived from in your Forefront Health Vitamin E Complex? I’ve been looking for a product like this where the Vitamin E is not from soy. Thanks!

  23. TINA March 28, 2020 at 5:46 am - Reply

    They say you need pufas for proper bile production.Is this true?and what about cold pressed pufa oils?

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