The Worst Cooking Oils For Your Thyroid: Use These Instead

The Worst Cooking Oils For Your Thyroid: Use These Instead

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Will eating fat help your health or hurt it? What about your thyroid?

The truth is that it really depends on what type of fat you are eating. 

But let’s be clear: the consumption of fat is essential for your body. 

Certain fats, called essential fatty acids, can not be created by the body and are required for very important cellular functions like promoting brain health, regulating metabolism, improving cognition, and more. 

Fat also provides your body with a source of calories and is one of the most potent regulators of appetite. 

All of this information is generally well-known. 

What isn’t as well known, is the negative impact that using the wrong types of fat can have on your body and your thyroid. 

I would even go as far as to say that the consumption of inflammatory oils may be a leading cause of chronic disease and inflammation that most people just aren’t aware of.

It doesn’t matter what type of health condition you have, eating the wrong type of fat can make it worse. 

And this is especially true for thyroid patients who tend to be more prone to inflammation than the general population. 

What makes this even more concerning is the fact that the majority of fats that you are coming into contact with fall into this inflammatory category and may be damaging your health and making your thyroid problem worse. 

Here’s why:


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#1. These Unhealthy Fats Are Found Everywhere (And In Everything). 

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The most unhealthy fats that you can come into contact with are often labeled and marketed as vegetable oils but this naming convention couldn’t be more misleading. 

The name vegetable oil gives you the idea that the oil came from something healthy, like a vegetable, which is exactly what the manufacturers of these oils want you to think. 

But the reality is that these fats are so processed that they barely resemble the plant or seed that produced them. 

For this reason, I think a much better name for them is industrial seed oil. 

But, as you might have guessed, the name industrial seed oil doesn’t sell well, which is why you’ll see them marketed as vegetable oils. 

But, as I mentioned, don’t let the highly misleading naming convention that they choose to use confuse you. 

Whether you refer to them as vegetable oils, industrial seed oils, cooking oils, or some other name, these are the most unhealthy fats that you can consume and they should be avoided. 

What types of cooking oils fall into this unhealthy category?

Allow me to introduce them: 

  • Canola oil
  • sunflower oil 
  • Safflower oil
  • Corn oil
  • Soybean oil
  • Cotton seed oil
  • Grapeseed oil
  • Rice bran oil

These cooking oils are by far the most toxic of all cooking oils available and they are found all over the place. 

If you don’t believe me, walk into your kitchen right now and start reading the ingredient list on the back of any processed food. 

Unless you are a seasoned ingredient label reader and know how to identify healthy food, I can almost guarantee that these oils are found in your house right now. 

There’s one reason for this: 

They are dirt cheap. 

Compared to healthier oils (which we will soon discuss), these oils are neutral (so they don’t alter taste), cheap (so manufacturers can make money), and easy to purchase in bulk. 

As a result, they are found in all sorts of foods and are heavily used in restaurants. 

This, by the way, is one of the main reasons that eating out is so unhealthy!

Have you ever found a restaurant willing to cook everything with extra virgin olive oil? 

If they used healthy oils, they’d have to increase their prices considerably. 

So the easier option is to just use low-quality, cheap, toxic cooking oils to keep their prices low. 

But, believe me when I say, if you eat these foods you will pay the price at some point. 

Part of the reason that these oils are so toxic has to do with their creation process. 

It’s well known that the more processed a food is, the less healthy it is for the body

The creation of industrial seed oils requires a multistep process that involves heating, dissolving, deodorizing, and the addition of chemicals to get the final product that you then cook with and put in your body. 

It’s no wonder why these oils cause so many problems when consumed.

The processing of these oils isn’t the only problem with them though which leads us to…

#2. Unhealthy Fats (Industrial Seed Oils) Contain High Amounts of Omega 6 Fatty Acids.

One of the biggest issues with these fats is their high concentration of omega-6 fatty acids. 

In your body, there exists a ratio between omega 3 fatty acids and omega 6 fatty acids. 

This ratio may not mean a lot to you but it’s really important when it comes to regulating inflammation. 

We know from research that higher levels of omega-6 fatty acids push on the gas of the inflammatory cascade (1). 

This is both good and bad. 

Bad because it means that eating these oils can lead to inflammation. 

But good because it means that avoiding them can positively impact inflammatory levels in your body. 

And this is a great thing for your thyroid health. 


Your thyroid gland is very sensitive to changes in inflammation to which it responds by reducing thyroid function

The more inflammation in your body, the worse your thyroid will function. 

Beyond the thyroid issue, inflammation is at the heart of just about every chronic disease you can think of and the use of these oils may either be contributing to their creation or making them worse. 

#3. They (Seed Oils) Stick Around in Your Body For a Long Time. 

Remember: your body stores excess calories and energy as fat. 

In addition, it also uses fat to protect your cells by incorporating them into your cellular membranes (2). 

Why is this important?

Because industrial seed oils, as a whole, are considered polyunsaturated fats which means that their chemical structure has a lot more double bonds than saturated fat. 

And these double bonds act as a point of weakness and as a point of potential oxidation. 

It’s easy to imagine a scenario in which the consumption of these fats allows for their incorporation into your cellular machinery. 

Do you think that their points of weakness will keep your cells healthy and functional or that they will hurt them in the long run?

Obviously, the latter, which is why they should be avoided. 

The problem with consuming these fats is that they do get incorporated into your cells where they can sit around for a long period of time. 

And all the while they are open to damage and oxidation from regular day-to-day activities. 

As they get damaged, they weaken your cell walls and compromise cellular function. 

This, in my opinion, is probably their worst attribute: 

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Their ability to promote oxidative stress. 

Oxidative stress is bad for all of your cells but it’s exceptionally bad for your thyroid cells. 

The low thyroid state compounds the effects of oxidative stress (3) and adding further fuel to this fire will certainly not help thyroid patients. 

The good news is that as you avoid industrial seed oils and fill your body with healthy fats, they will take the place of these unhealthy fats in your cells and in your fat tissues over time, resulting in better health for you overall. 

The only downside is that it can take several months to turn over and replace these unwanted fats. 

#4. The Reheating of Industrial Seed Oil Results in The Creation of Toxic Byproducts. 

On top of being inflammatory all by themselves, industrial seed oils are often heated and reheated by both restaurants and the at-home cook (4). 

This process takes an already unhealthy base and makes it even more unhealthy. 

Heating oil destabilizes it, changes its structure, and results in the creation of polycyclic aromatic hydrocarbons which are potentially cancer-promoting. 

Because these oils are so cheap and because they are frequently used by fast food restaurants where they are repeatedly heated and reheated for frying, they are prone to creating these toxic byproducts. 

Add this to the fact that these oils are highly fragile and more prone to oxidation, you have a double whammy, and not in a good way. 

This means that even if you aren’t reheating them over and over again, they are still causing problems compared to their unprocessed counterparts (more on this in a minute).  

#5. The Conventional Food Establishment Is on a Mission To Convince You That These Fats Are Healthy. 

I’m not necessarily claiming malicious intent here, but there seems to be a push to try and get as many people as possible to consume these oils by calling them heart-healthy

You can find this information on all sorts of major websites and organizations including the American Heart Association where canola oil is touted as one of the most heart-healthy oils available. 

It’s easy to look at this information and come to the conclusion that these oils must be healthy because why else would the American Heart Association promote them?

What makes this more confusing is the fact that there are plenty of studies that seem to suggest that these oils are, in fact, heart-healthy (5). 

You can read through all of the research and competing viewpoints when it comes to these oils but let me tell you how I think about it: 

With record levels of thyroid disease, obesity, diabetes, and chronic disease in general, do you honestly feel like the standard dietary advice is working?

It’s hard to look at the data over the last 20 years and claim that the standard advice is worth something when we see that heart disease continues to be the number one cause of mortality in developed countries.

We know for sure that people are eating more of these oils than ever before, so it seems suspicious that heart disease continues to rise. 

But beyond this, do you think it makes sense to consume an oil that has undergone 15+ different steps in order to be palatable to humans 

Or does it make sense to consume a cold-pressed oil from an unprocessed source?

It’s clear that processed foods directly correlate with disease so why would processed oil be the only exception?

I’ve spent a lot of time reading, researching, and experimenting with my own body and I’ve come to the conclusion that eating the least processed version of food is always the best option. 

And part of the reason that I know this is because I’ve tested both options!

I feel so much better when I avoid processed foods and when I avoid industrial seed oils. 

And if you are someone who has not been feeling very well or is suffering from thyroid disease or other chronic diseases, then it may be time to try something like that out. 

But at the end of the day, you’re an adult and you can make whatever decision you want. 

Eat These Cooking Oils For Better Thyroid Health

If you’ve found this information interesting and you want to try and avoid your exposure to these unhealthy cooking oils then here’s what you’d want to replace them with: 

  • #1. Extra virgin olive oil – This (truly) heart-healthy oil has been used for thousands of years and is a big part of the Mediterranean diet which is known to be anti-inflammatory in nature. It contains a rich source of oleic acid and polyphenols (such as oleocanthal (6)) which impart beneficial anti-inflammatory, anti-cancer, anti-atherogenic, immuno-modulatory, neuro-protective, and hepato-protective benefits (7). In other words, this cooking oil is great for your entire body. 
  • #2. Cold-pressed coconut oil – This oil is loaded with medium-chain triglycerides (8) and has additional benefits like acting as an antifungal, antiviral, and antibacterial agent. 
  • #3. Grass-fed butter or ghee – These foods contain conjugated linoleic acid and fat-soluble vitamins like vitamins A, D, E, and K2


This is just a list of cooking oils so make sure to also get as many healthy fats as possible from your diet, especially omega-3 fatty acids, from whole foods like fish, meat, nuts, and seeds. 

Eating these minimally processed oils and fats will provide benefits to your thyroid and body in more ways than one. 

And if you don’t believe me, you can always give it a test. 

Ditch the industrial seed oils for 30 days and see what happens when you only consume the fats listed above. 

I can promise you that eating extra virgin olive oil for 30 days is NOT going to cause any serious problems, but ditching industrial seed oils has a big chance of helping you feel better. 

The risk vs reward ratio here is pretty lopsided in your favor.

If you are someone who has been eating a lot of these inflammatory oils then you might also want to take steps to reduce inflammation in your body. 

If that’s the case then I would strongly recommend checking out this article next which highlights the most powerful anti-inflammatory supplements available

Now I want to hear from you: 

Were you aware of the potential danger of these oils?

Are you someone who is already actively avoiding these oils in favor of other cooking oils?

Are you planning on making any changes to your diet after reading this? Why or why not?

Leave your questions or comments below! 

Scientific References









These cooking oils are damaging your thyroid

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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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