The Thyroid Foods You NEED to Avoid (Backed by Research)

Added: 2026-05-11

[00:00:02]So now that you have a little understanding about the role of nutrition, let's talk about the source of that nutrition, which is the food that you eat. Your food can be your best friend or it can be your worst enemy.

[00:00:13]And there are three foods that we see drive thyroid problems more than any other three. And this is this has been reported on in medical literature. This has also been my experience in practice and many other of my colleagues experience in practice. But if you could change three things today to improve your thyroid function, you would go gluten-free, you would go dairyf free, and you would go sugar-free. Now, that may seem overwhelming to many of you, but I want to draw some connections for you as to why. It's important that you know why so that you have uh better motivation, if you will, to embark upon these changes. When we look at some of the medical research on going gluten-free and the thyroid, right? So in this study, this was done in humans.

[00:01:00]So gluten-free diet reduces antibbody concentration. This is thyroid antibody concentration and regulates thyroid autoimmunization.

[00:01:09]The medit Mediterranean diet reduces oxidative stress. So it helps reduce inflammation.

[00:01:15]This study evaluates the short-term effect of a Mediterranean diet, a gluten-free diet, and a combined Mediterranean gluten-free diet pattern on thyroid function and antibbody levels of patients.

[00:01:29]So, they did this study where they put people on these diets, these different diets for 12 weeks. What did they find?

[00:01:35]They found that free T3 that the active thyroid hormone free T3 increased significantly in people on a gluten-free diet and in people on a Mediterranean diet and in people on the combined Mediterranean gluten-free diet. So in all intervention groups with the highest increase in the people that followed a Mediterranean plus gluten-free diet. They also found the thyroid antibbody levels the TPO and the thyrolobuline antibodies decreased after the intervention. So what happened in these patients with autoimmune thyroid disease is when they changed their diet the autoimmune antibbody levels dropped and the amount of active thyroid hormone increased. Right? Okay.

[00:02:23]So, we go back, we say, okay, what active thyroid hormone, that's this stuff right here, the active thyroid hormone that talks to the cell that allows for increased metabolism.

[00:02:36]This increased with diet change.

[00:02:42]So coming back to some additional research on diet change and gluten, we know that gluten can elevate thyroid inflammatory antibodies for up to six months. This study showed it. They they actually looked at people's blood. They looked at 100 patients with autoimmune thyroid disease. And what they found with gluten exposure is that the cerological markers became undetectable 6 months after beginning a gluten-free diet. So it took that long the antibodies and some of the studies that have been done on gluten that are negative. Meaning they they said we put these patients on a gluten-free diet and it didn't change their antibodies. They didn't keep them on the diet long enough.

[00:03:23]Six months the markers become undetectable. But that half-life of gluten antibodies, meaning that the time it takes for half of the antibodies to get out of your system is about 3 months. So we may see some early reductions at 3 months, but we're not going to see them go away for a little bit longer than that. And this study showed it took six months. So if you're trying to go gluten-free and your doctor is maybe monitoring your antibbody levels and they're not moving as fast as you wanted them to, remember that number. Six months.

[00:03:56]Now, in this study, the effect of gluten-free diet on autoimmune thyroiditis, um, here's what they found. Our results seem to indicate a positive effect of the gluten deprivation on thyroid function and its inflammation, meaning it reduced thyroid inflammation and improved thyroid function, particularly in patients with Hashimoto's and with gluten related conditions. What's gluten-related condition? If you're not familiar with that term, I encourage you to visit gluten-free society. It's our hub and read more about the different types of conditions linked to gluten.

[00:04:34]But some examples would include hypothyroidism or Hashimoto's disease, Graves disease, rheumatoid arthritis, lupus, scleraderma, dermatomyioitis, ankylosing spondylitis, and myastthenia gravis and multiple sclerosis. Many different types of autoimmune diseases are gluten related conditions. And this is another study that was published on the effect of the gluten-free diet on thyroid autoimmunity.

[00:05:03]The gluten-free diet reduced thyroid antibody tighters as well as increased vitamin D levels. So, improved vitamin D levels. Now, why would a gluten-free diet actually enhance vitamin D? Because gluten damages the gut and it causes malabsorption of nutrients.

[00:05:25]So, vitamin D being one of those nutrients we absorb through our GI tract. But gluten also drives inflammation.

[00:05:33]And the more inflamed somebody is, the more vitamin D they need. So when you're inflamed, your body uses up more vitamin D to try to protect you. Vitamin D has immune regulatory and anti-inflammatory effects. So there's two mechanisms by which gluten can drive vitamin D deficiency, malabsorption, and inflammation. And in this study, they showed that just going gluten-free improved vitamin D levels.

[00:06:06]We got another one here on the presence of antigleen antibodies in autoimmune thyroid disease. They were studying patients with autoimmune thyroid disease and what did they find?

[00:06:17]They found um polyglangular endocrine syndrome is the commonest cause of positivity of antigladen antibodies in the patients with autoimmune thyroid disease. What does that really mean?

[00:06:28]Poly glandular endocrine syndrome. So gluten is known to cause polyglandular endocrine syndrome. This is where multiple endocrine organs become affected. The thyroid can become affected. The pancreas which makes insulin and digestive enzymes that gland can be affected. U the adrenal glands can also be affected. Ladies, the ovaries uh and the uterus can be affected. Men, the testes can be affected. So the endocrine glands, the endocrine system itself, one of the most common drivers of endocrine disruption is gluten. Okay. And so what they found is that many of these patients had positive antibodies against gluten indicating they needed to stop eating it so that they can quiet the inflammation that it's driving.

[00:07:19]Here's another one on this was a metaanalysis of many studies. So the effects of a gluten-free diet on autoimmune thyroid disease. This is the first meta analysis investigating the effect of gluten-free diet on hypothyroidism. Our results seem to indicate a positive effect of gluten deprivation on thyroid function and its inflammation particularly in patients with Hashimoto's and gluten- related conditions as we mentioned. Now, one of the other connections between gluten and the thyroid is the microbiome. When we eat gluten, one of the side effects here is called leaky gut. Now, when your gut is leaking, it allows proteins and other toxic compounds that your gut is supposed to poop out, it allows those things directly into your bloodstream. Gluten can drive leaky gut. And it can also drive damage to healthy bacteria, the microbiota. And the microbiota have many different functions. One of their functions is they help regulate the immune system and regulate autoimmune reactions. That's AITD. That's autoimmune diseases. In this case, autoimmune thyroid disease. Um, so we know gluten drives leaky gut, which can alter the microbiome, which can contribute to the development of autoimmune thyroid disease. We know in human trials that when probiotics are given, there's beneficial effects um on thyroid symptoms. We know that celiac disease, which is a common manifestation of gluten, is highly linked to thyroid disease. They're they're part of the same family of autoimmune conditions. So bottom line, gluten can drive leaky gut, otherwise known as intestinal permeability.

[00:09:08]That can affect the microbiota driving autoimmune disease. But it can also, if you come over here, it's affecting the microbiota. It influences how we absorb and digest our food, but also how we make certain vitamins. The flora, the gut bacteria, make B vitamins and vitamin K. It's part of their job.

[00:09:31]It's part of how they help keep us nourished. We feed them. They feed us back by giving us B vitamins and vitamin K. So, this is where you see here micronutrient deficiencies. When we damage our healthy bacteria, we can develop micronutrient deficiencies. But also if we eat gluten and that causes damage to the intestine, this also drives micronutrient deficiencies through malabsorption. And so when we think about what I showed you earlier, which is there are several nutrients that you need for your thyroid hormone to be properly regulated, iron and iodine are reduced. This impairs the body's ability to make thyroid hormone.

[00:10:09]Selenium and zinc drop, which reduces our ability to convert T4 to T3. So understand the thyroid gut axis is the connection between how your gut influences the effectiveness or the role that your thyroid plays. In some ways it's altered permeability driving inflammation and autoimmune disease. In other ways it's altered nutrition. It's driving malnutrition or micronutrient deficiencies leading to poor thyroid hormone formation.

[00:10:39]Okay. Now that we've established a thyroid gut axis and we know nutrition plays a major role, let's look at some of the human studies on nutrition and your thyroid. These are the studies your doctor will never have told you about.

[00:10:52]They will have dismissed if you ask them about nutrition. They'll say there isn't a connection. And what I'm showing you now is the connection so that you're armed with knowledge to make a better decision. And stay with me because we're going to get to shortly the testing you need to ask your doctor for and the um the doses specifically of of nutrients that you can take and how much you should take and how they might help you.

[00:11:18]So we'll cover that too. But let's start with looking at this study. This is a great uh review published on the role of nutrition on thyroid function. And so I'm just going to highlight a few things in this for you. Um, one on iron. You can see down here, um, iron is important for producing a protein, um, enzyme that lives inside of your thyroid gland called TPO, thyroid peroxidase. And this enzyme is important for the production of thyroid hormone.

[00:11:55]And iron is the centerpiece. It's like the center atom of this enzyme. Now I mentioned earlier there were some there were some tests the TPO um thyroid peroxidase there's an antibbody that we produce to TPO when we have autoimmune disease.

[00:12:15]So this is part of the problem with autoimmune thyroid disease is it destroys TPO, right? But iron deficiency takes TPO and makes it and it makes it hard for the body to produce it. So when you're low in iron, TPO is reduced and thyroid hormone production becomes problematic. We know this is very common. Iron deficiency can be a risk factor for thyroid disorders during pregnancy because of the increased demand of blood volume and growing a new baby and that requires a lot of iron. We know that it correlates with changes in the activity of this enzyme and the reduction of the conversion of T4 to T3. So what's actually happening is the that iron deficient pregnant woman will make less of the active thyroid hormone that helps the baby grow. And this is why many babies when when this is the case can be born with creatinism and other health problems that are associated with poor thyroid hormone function as a result of iron deficiency.

[00:13:15]We also know even in non-pregant women that iron deficiency and anemia are linked to hypothyroidism. They're they're linked to low thyroid function even non-autoimmune low thyroid function.

[00:13:28]For zinc, we know that within the thyroid gland, zinc plays a role in this in the activity of that same enzyme, that TPO enzyme, which is essential for the synthesis of thyroid hormones. This enzyme catalyzes or allows for the energy of of helping the protein thyrolobuline become iodinated. What that means is there's this protein, this very important protein called thyrolobuline and thyrolobuline is made out of tyrrosine. Tyrrosine is an amino acid we get from eating protein. This is why not having enough protein oftentimes can also drive low thyroid function. But tyrrosine helps make thyrolylobulin.

[00:14:10]And then zinc helps add iodine to tyrrosine and that's that's an essential element or an essential component for being able to produce thyroid hormone. So zinc plays that role. Zinc deficiency can also impair thyroid hormone receptor function. So thyroid hormones have to dock to cells to communicate to the cell to increase your metabolism and there's a receptor for that and without adequate zinc that receptor will not work as well. So you could have normal amounts of thyroid hormone. Your doctor could measure your thyroid and you feel tired and you're losing hair, but your doctor's like, "No, you don't have thyroid disease." And it's possible that you have a zinc deficiency that's interfering with the hormone receptor so that your thyroid hormone can't talk to your cell about improving your metabolism. We also know that zinc deficiency has been linked with thyroid enlargement in children. Goiters.

[00:15:10]Look, thank you for tuning in to Dr. Osborne Zone. I hope this information is helpful for you. Do me a favor. If you like this information, hit the like button below and subscribe if you're not already. And come visit me at Gluten-Free Society. If you come over there, sign up for our free newsletter.

[00:15:29]We'll send you a ton of information on the thyroid and on nutrition and how to navigate lifestyle and diet changes to overcome autoimmune disease. Thanks so much for tuning in. Make sure you join us as well on Thursday 12:30 p.m. We'll be doing a live Q&A. at central standard time on all of your thyroid questions.

[00:15:50]And if you want to get the notes, if you want to get the slide deck, and you want to get my definitive guide on the thyroid, just chime in below. Comment thyroid in the comment section, and we'll send that to you. Have a fantastic evening.