The Thyroid and Diet

We’re still talking about gut health for a little bit longer.  Today our focus is on the thyroid and its connection to the gut.  According to the American Thyroid Association, 20 million Americans have some form of thyroid disease, and up to 60 percent of them aren’t even aware. (1)  That’s about 8% of the adult population affected by a thyroid condition.  That may not seem like a lot, but let’s dig deeper.  Women are five to eight times more likely to suffer from a thyroid condition; and according to the American Thyroid Association, 1 in 8 women will be affecting by a thyroid condition at some point in their lifetime.  That is the same statistic for breast cancer; 1 in 8 women. (2)  Why are women more susceptible?  I can’t say for certain, but there is a link between pregnancy and thyroid dysfunction.

During pregnancy, the thyroid can become inflamed from white blood cells called lymphocytes in a condition called lymphocytic thyroiditis (a.k.a. Hashimoto’s thyroiditis, which we’ll discuss in a bit).  According to one article, this is not uncommon and the thyroid eventually returns to normal.  Although sometimes it does not.  I can say from experience that my thyroid issues started after I had my daughter.  This now makes sense to me, knowing it may not have just come out of nowhere.  Why might this happen?  There’s a long-standing debate going on around women, pregnancy and autoimmune disorders.  I won’t go into it here, but we can look at the issues and see why this might happen.  Having another person inside of you is definitely a foreign invader in the eyes of the immune system, and while carrying a child, the cells from the fetus intermingle with the woman’s blood. (3) Women are more likely to suffer from autoimmune disorders than men.  Men do not have this exposure.  I am certain it is not this simple, but I do find it interesting.

Back to the eerily identical statistic for thyroid and breast cancer in women.  I can’t say for certain if there’s any connection, but I will tell you this.  I am included in both of those categories.  Thyroid disease runs in my family and I have lost both my mother and her sister to cancer.  We’ve seen how so many conditions are affected by gut health and what we eat, so it is not surprising to me that all these conditions could be linked by a common root issue.  The difference is in how the root issue manifests in each person.  So let’s take a closer look at the thyroid, its function and its connection to gut health.

What is the Thyroid?

The thyroid is a butterfly shaped gland that sits at the front of the lower part of the neck just below the Adam’s apple.  You cannot feel it unless it is enlarged.  It has a left and right lobe which are located on each side of the wind pipe, or trachea.  You need to know just how important this small gland is to the regulation of bodily functions.  Here is a list of some of the functions in which the thyroid plays a role:

  • Metabolism
  • Immune function
  • Weight
  • Sex hormones (and menstrual cycles)
  • Blood pressure regulation and heart rate
  • Tissue development
  • Energy levels
  • Sleep
  • Breathing
  • Body temperature

This list is not all inclusive, but meant to give you an idea of just how many functions are impacted by thyroid health.  Read over that list again and consider if any of these are areas of concern for you.  For example, are you often colder than everyone else?  Do you struggle to maintain a healthy weight?  Are your menstrual cycles irregular or have you had difficulty getting pregnant?  Do you suffer from fatigue, heart palpitations or anxiety?

The thyroid works in concert with the pituitary gland and the hypothalamus (in the brain) to regulate the levels of thyroid hormone in the body.  As with all our hormones, there is a delicate balance.  When out of balance, the hormones impact one another and trigger a myriad of symptoms that are similar.  For example, I mentioned menstrual cycles and infertility.  These are also symptoms of other types of hormone imbalance, not just the thyroid hormones.  That’s why testing is so critical and we’ll talk more about that later.

Types of Thyroid Disorders

There are three main thyroid disorders:

  • Hypothyroidism
  • Hyperthyroidism
  • Goiter

We tend to look at the thyroid in terms of hypothyroidism, an under-active thyroid; and hyperthyroidism, an over-active thyroid.  Under and over is used to indicate whether the thyroid is producing too little or too much thyroid hormone.  When the condition, either hypo or hyper, is caused by an autoimmune disorder it is typically classified as Hashimoto’s thyroiditis (hypo) or Graves’ disease (hyper).  A goiter, on the other hand, is a non-cancerous enlargement of the thyroid which can be caused by iodine insufficiency or hyperthyroidism.

Symptoms of hypothyroidism include:

  • Unexplained weight gain
  • Hair loss
  • Dry skin
  • Sensitivity to cold temperatures
  • Frequent heavy periods
  • Joint and muscle pain
  • Brain fog
  • Mood swings
  • Fatigue

Symptoms of hyperthyroidism include:

  • Unexplained weight loss
  • Insomnia
  • Brain fog
  • Difficulty concentrating
  • Anxiety
  • Tremors
  • Bulging eyes
  • Heart palpitations
  • Nervousness, hyperactivity or hand trembling
  • Missed or light menstrual periods
  • Sensitivity to high temperatures and sweating

Symptoms of goiter include:

  • Hoarseness
  • Swelling in the neck around the thyroid
  • Coughing or wheezing
  • Difficulty breathing or swallowing

Earlier I talked about Hashimoto’s and pregnancy.  When the condition is chronic and does not go away, it can develop into Hashimoto’s hypothyroidism.  This is a result of autoimmune disease.  Autoimmune meaning the immune cells attack healthy, normal cell tissue instead of protecting it.  The immune system sees the normal body’s tissues as foreign, when they are not.

So other than potentially pregnancy, how do environmental triggers causing the body to attack its own tissues get into the body?  Keep in mind that the body is a closed system.  In order for anything outside the body (even in the gut) to enter the bloodstream, it must have a way in.

Thyroid Disorders and the Gut

We’ve discussed leaky gut, or intestinal permeability, and how it allows toxins into the body.  I also pointed out earlier that up to 80% of our immune system is located in the gut.  The thyroid gland is very sensitive to issues with the immune system and thus affected by everything going on in the gut.  This is because bacteria in the gastrointestinal tract play a role in the conversion of thyroid hormones in the bloodstream; specifically the conversion of the thyroid hormones T4 to T3.

When there is dysbiosis in the gut and/or leaky gut, the conversion of T4 to T3 can be impaired.  It can also cause the production of the inactive form of T3 (reverse T3).  When reverse T3 levels are out of balance, hypo or hyperthyroidism can result.  Another way thyroid hormone levels are affected by gut permeability is through cortisol levels.  Recall that stress increases the production of cortisol.  When immune system tissues in the gut are irritated, it is a stressor to the body.  This stressor increases cortisol production, which in turn decreases thyroid hormone production.  This is another example of just how intertwined the body’s hormone (endocrine) system is, and how delicate the balancing of hormones.

Gut disorders that occur with thyroid autoimmune disease include celiac disease (4), heartburn (5), and leaky gut (6, 7, 8).  There is also evidence that people with autoimmune disease tend to have altered gut bacteria (9).  Why?  The lining of the gut has many endocrine cells which have numerous receptors for thyroid hormone.  When the lining of the gut is damaged, these cells cannot function properly by producing the mucus necessary to protect the intestinal walls.  This in turn creates an environment ripe for leaky gut, as thyroid hormone plays a role in maintaining the tight junctions of the intestinal lining.

Also keep in mind that inflammation can impair digestion and absorption of nutrients, which will lead to the thyroid not getting the nutrients its needs to function properly.

Thyroid hormones are also involved in triggering the production of stomach acid.  Hypothyroidism can result in decreased levels of stomach acid, and subsequently result in heartburn.  Stomach acid, in turn, is necessary for the release of digestive enzymes.  These enzymes, you may recall, are responsible for the proper digestion and absorption of food and the nutrients in food.  When food is not properly digested in the stomach, it can pass on to the small intestine and cause gas, bloating and bacterial overgrowth (SIBO).

The migrating motor complex can also be affected by thyroid disorders.  It is not uncommon for there to be an increase or decrease of motility time through the intestinal tract, resulting in constipation in hypothyroidism and diarrhea in hyperthyroidism.

Diagnosing and Supporting Thyroid Disorders

Because the endocrine system is so complex and its hormones so intertwined in their dependance on one another, it is critical that proper testing be done to determine exactly what isn’t working.  If you suspect your thyroid is at issue, make sure to have your thyroid hormones fully tested.  Many doctors will only test for basic levels like TSH and T4.  The problem is this can miss some other factors like reverse T3 and any antibodies being produced against the thyroid which would indicate or rule out autoimmunity.

A proper thyroid panel includes:

  • T3 Free
  • T3 Reverse
  • T4 Free
  • TSH, and
  • Thyroid Antibodies

Since the thyroid is highly sensitive to toxins, protecting the thyroid and the gut is critical.  Here are some things to consider in conjunction with testing and consultation with your doctor to support thyroid health:

  • If gut dysbiosis is present, keeping an eye on carbohydrate intake can help.  Too many carbs feed the bad bacteria and make dysbiosis worse.
  • If gut dysbiosis is not a factor, maintain a healthy level of carbohydrate intake.  Too low of an intake could trigger hypothyroidism or make symptoms worse by dropping insulin levels too low.  Insulin, another endocrine hormone, can affect the conversion of T4 to T3.  T4 is the inactive form of thyroid hormone.  If insulin is too low, it can hamper the conversion.
  • Obtain your carbs from fiber rich, whole foods like vegetables and fruit and reduce intake of refined sugars and processed foods.
  • Another area that would be helpful in testing is mineral levels.  A healthy thyroid requires adequate levels of nutrients like iodine and selenium.  Selenium is needed to convert T4 to T3.  Two Brazil nuts a day provide the recommended daily allowance of selenium.  But don’t go overboard, as there is such a thing as too much selenium.
  • Unless you have digestive issues with cruciferous vegetables, or inadequate iodine levels, these vegetables are  very beneficial to the thyroid and the body in general.  It is recommended that steaming them reduces the goitrogenic affects you may have read about that caution against eating them if you have a thyroid disorder.
  • Eat fermented foods like kimchi and sauerkraut to support healthy gut bacteria.
  • Balance your Omega-3’s and Omega-6’s.  Healthy fats reduce inflammation in the body, whereas unhealthy (processed) Omega 6’s increase inflammation.
  • Consider removing or limiting dairy consumption.  The molecular structure of the proteins in gluten and dairy resemble the thyroid.  These are common allergens/irritants of the immune system.  If your immune system is reacting to these it may be causing the immune system to also attack the thyroid because of the similarity in molecular makeup.
  • Reduce your toxic burden.  Chemicals, including endocrine disruptors, like chlorine (in water), plastic, pesticides and many personal care items can interfere with the thyroid as well as contribute to excess estrogen in the body (which we will cover next).  Avoid bottled water and get yourself a glass bottle and a good water filter to reduce the chemicals in your drinking water.
  • Limit exposure to heavy metals.  You may not realize it but they are everywhere; from our food to the air we breathe.  If you eat fish, eat wild-caught smaller fish known to be lower in mercury.  Also, keep your rice consumption down.  Rice absorbs arsenic from the ground naturally.  It’s also high in carbohydrates.  You can have heavy metals blood testing done to see where your levels are.  If they are high, you can take steps to detoxify these metals.

I cover a lot of these protective measures in my Daily Habits guide, which you can grab below, as well as in my 30-day program.  This was a lot of material and it provided a mere tidbit of information on the thyroid, but I hope it shed some light on how diet and gut health play a role in thyroid health.

Yours in Wellness,


Healthy Habits


  1. Jackie

    I completely understand. The body is a complex system with so many interrelated components. The endocrine system, which includes our hormones, is probably one of the most complex. My goal in presenting all of these gut health articles is to show just how interrelated they are, as well as how they can all be affected by what goes on in the gut. If you haven’t already, I urge you to go back to the in the series ( January 28th) and read through to current. It’s a lot, but it may help. Part of the problem is that we get so caught up in the details that we miss the bigger picture. I’m working on your other request.

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