Soy and Thyroid Controversy: Will it Make Your Thyroid Worse?

Soy and Thyroid Controversy: 3 Reasons to Avoid it with Thyroid Problems

Soy: Helpful or Harmful? The Soy Controversy

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Is soy this amazing plant compound that fights cancer, helps support your heart and bones, or is it something that will damage your thyroid gland and make your hypothyroidism worse?

Well, it depends on which study you are looking at!

In a nutshell, this is the soy controversy and this is why we are taking the time to break down the facts. 

There’s no question that the foods that you put into your body have an impact on your overall health. 

Putting the right foods into your body can reduce inflammation, support thyroid function, and help you feel better. 

On the other hand, putting highly processed and inflammatory foods into your body will cause you to gain weight, increase your risk of developing cancer, and cause many other problems to your health (1). 

The real question is this:

Where does soy fall? Is it a “good” thyroid good or a “bad” thyroid food?

The answer, like always, is probably somewhere in the middle. 

Today we are going to talk about this topic but specifically in the context of thyroid patients. 

Why? Because my blog and website focus almost solely on that very topic! 

In this article, I’m going to make the case as to why I believe that MOST thyroid patients are better off avoiding foods that contain soy. 

Article highlights:

  • Some medical studies show that soy may be beneficial while others show that it may be harmful but soy is probably best avoided in thyroid patients for the following reasons. 
  • Soy can stimulate estrogen receptors potentially leading to weight gain and other estrogen-related symptoms. 
  • Soy can act as a goitrogen by blocking the uptake of thyroid hormone and making thyroid function worse. 
  • Soy is heavily processed which may remove the beneficial ingredients in many soy products.


Foods to Avoid if you Have Thyroid Problems:

I’ve found that these 10 foods cause the most problems for thyroid patients. Learn which foods you should avoid if you have thyroid disease of any type.


The Complete List of Thyroid Lab tests:

The list includes optimal ranges, normal ranges, and the complete list of tests you need to diagnose and manage thyroid disease correctly!


3 Reasons Why I recommend that Soy Be Avoided If You Have a Thyroid Problem

When you take a look at the research and dietary studies on soy you will find that there is a split down the middle. 

There are a handful of studies that show that soy is potentially helpful, a handful of studies that show that it may not be helpful, and a handful of studies that show that it may be harmful. 

What is a thyroid patient supposed to do? 

Put your head in the sand, plug your ears, and keep on putting foods into your body that may or may not be good for your thyroid?

Please don’t! 

Instead, I want to break down 3 solid reasons why soy has the real potential to cause problems for thyroid patients. 

And you don’t have to get deep into the research to understand these concepts. 

Let’s jump in: 

#1. Soy has an estrogenic effect on the body. 

Soy products have what is referred to as an estrogenic effect in the body (2). 

In simple terms, this means that there is some part of the soy which can interact with estrogen receptors. 

This process sort of tricks your body into thinking that estrogen is impacting your cells when it’s really the soy doing it. 

When soy interacts with the estrogen receptor it can cause a cascade of events that turn on your cell and impact your physiology. 

should soy be avoided for thyroid health

As a woman, you are probably well familiar with what this feels like. 

If estrogen interacts with your breast tissue then it will grow and swell (often experienced as breast tenderness (3) during your menstrual cycle). 

If estrogen interacts with fat cells then it may cause your fat cells to grow (which is what occurs in estrogen dominance syndromes). 

If estrogen interacts with your heart cells then it may help prevent cardiovascular disease (which is why heart disease increases (4) as estrogen falls in menopause). 

If estrogen interacts with your bones then it may prevent osteoporosis (which is why women have a decrease in bone mass when estrogen falls in menopause). 

Soy can have this effect on various estrogen receptors in the body and on various cells in the body. 

And, as you can see, it can sometimes be a good thing to impact estrogen receptors, especially if you are trying to do something like prevent heart disease later in life or to strengthen your bones. 

This is probably why soy can be helpful for certain conditions such as improving the heart and potentially reducing your risk of certain cancers. 

On the flip side, it can also be potentially harmful, especially if you are already overweight or suffering from estrogen excess syndromes. 

The problem with taking soy is that you can’t really control which type of estrogen receptors it’s going to trigger or impact which is why it may not be a good idea to use it if you have a thyroid problem. 


Because many patients with thyroid problems tend to suffer from weight gain because of their low thyroid function. 

And if you are already overweight the last thing you want to do is add more stimulation to your fat cells which may cause them to grow further. 

In addition, being overweight predisposes you to excess estrogen circulating in your body. 

Your fat cells are hormone sensitive tissues and they are capable of taking up androgens and turning them into estrogen. 

If you already have excess fat on your body then you are most likely in a state of estrogen excess. 

This, by the way, is why women who are overweight tend to have fewer menopausal symptoms when they enter menopause. 

This may be a good thing for some women but it’s not really a good thing if you are a thyroid patient. 

Taking soy, especially if you are overweight or obese, may cause excessive stimulation of estrogen receptors and exacerbate estrogen dominance states or syndromes. 

#2. Soy can act as a goitrogen. 

There’s no disputing the fact that soy has what is referred to as a goitrogenic effect on the thyroid. 

If something is acting as a goitrogen it means that it is blocking the uptake of iodine into the thyroid gland

And this is something that soy does. 

In addition, there are also some studies that show that if you put soy in contact with thyroid peroxidase that it may cause issues with this enzyme. 

Fortunately, it doesn’t look like this is a big problem in the real world but it’s still worth mentioning here. 

For now, I want to focus on the goitrogenic effect that soy can have. 

For most people, this blocking of iodine is probably very small and manageable provided that you are consuming enough iodine. 

And that’s the key here, provided you are consuming enough iodine. 

Even though goitrogens can block iodine uptake into the thyroid gland you can overcome this blocking by simply taking more iodine. 

If there is more iodine than there is goitrogen, then the iodine will be able to get through the blockade and you won’t have any issues. 

We have to put this knowledge into context with how most thyroid patients feel about iodine. 

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The truth is that many thyroid patients have an irrational fear of iodine, or they were told to avoid it by their doctor, or they believe that it may trigger Hashimoto’s, and, therefore, they are not consuming enough. 

So if you are someone who is already not consuming enough iodine then even small amounts of soy may be enough to block what little iodine you have floating around in your body from getting into your thyroid gland. 

If this occurs then you will have issues in producing thyroid hormone and it may actually have a negative impact on thyroid function. 

Does this mean that every single person who is consuming soy products will have low thyroid function because they can’t get iodine into their thyroid gland? 

No, probably not. 

But it is absolutely something you should be aware of especially if you are someone who is actively avoiding iodine! 

If you are someone taking supplements that contain iodine already then consuming soy will probably not have any impact on thyroid function. 

#3. Soy is heavily processed and around 90% of all soy products are genetically modified (GMO). 

Another big reason to avoid soy is that the vast majority of all soy products are heavily processed and genetically modified. 

When you break apart the soy compound you will find that many of the beneficial health effects come from something called soy isoflavone (5). 

This isoflavone is the flavonoid or plant compound found in soy products and it is this ingredient that is felt to be the main reason why soy may help prevent breast cancer and protect the heart. 

But there’s one big problem:

The processing of soy removes a huge amount of this very ingredient!

So if you are consuming soy products hoping to get these beneficial effects, but you are consuming a processed version, then you are probably not getting anywhere near the level that your body needs. 

Not only does processing remove beneficial ingredients like isoflavone, it also has the potential to result in inflammation.

Inflammation can wreak havoc in thyroid patients by reducing T4 to T3 conversion resulting in low levels of the most important thyroid hormone T3

I’ve talked a lot about food processing and why it causes issues and why I recommend that thyroid patients avoid processed foods in articles such as this one

The good news is that you can probably get around this particular problem by only consuming soy products that are non-GMO, organic, and which have not undergone processing. 

So… Should You Use Soy?

Is there a situation in which you can consume soy if you have a thyroid problem?

The answer is yes. 

If you break down the reasons I listed above for why it should be avoided, and if you don’t have to worry about these problems, then there may be a scenario in which you can reap the benefits from soy while avoiding the potential consequences to your thyroid gland. 

If you are someone who is not already overweight (so you don’t have to worry about estrogenic activity, who is consuming enough iodine (so you don’t have to worry about the goitrogenic effect), and if you consume organic/non-processed version of soy, then you may not have any issues. 

Having said all of this, you still should pay close attention to how your body reacts when you put soy into your body and diet. 

It’s been my experience that most thyroid patients do feel better off of soy products and this number is much higher than those who can consume soy without any issue. 

But if you are someone that really, and I mean really, loves soy products then you can give it a go and experiment with some trial and error. 

Final Thoughts

While the science may be mixed when it comes to the benefits of soy consumption, I think the data is quite clear when it comes to thyroid patients. 

In most cases, and for most thyroid patients, the cons of consuming soy far outweigh the pros which leads me to believe that most thyroid patients are better off avoiding it. 

Having said that, there may be situations in which soy consumption is both safe and beneficial for thyroid patients. 

Now I want to hear from you:

Are you someone avoiding soy?

Did you know that soy could be potentially harmful to your thyroid gland?

Are you someone actively consuming soy and avoiding iodine? 

If so, do you think soy is impacting your body’s ability to create thyroid hormones?

Let me know in the comments below! 






3 reasons to avoid soy if you have thyroid problems

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

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#1. Get my free thyroid downloads, resources, and PDFs here.

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