What Does Your Thyroid Do? And Why It Matters

By Corri Peterson

What does your thyroid do is not an easy question to answer. For starters, the thyroid is one of eleven major regulatory systems in the body that make up the Endocrine System.

This system consists of glands that produce and secrete hormones. The thyroid is one of the essential glands in the Endocrine System. Metabolism, sexual function, and bodily growth are established and regulated through the hormones secreted by the thyroid. These hormones are chemical messengers that transfer information from one group of cells to another to coordinate and control multiple body parts’ functions.

When the thyroid is not functioning as it should, your body doesn’t interact correctly, creating various uncomfortable symptoms. Common low thyroid symptoms can include fatigue, poor concentration, constipation, weight gain, skin issues, dry, coarse, thinning hair or hair loss, and even depression and anxiety.

You probably know that the thyroid gland is vital for weight control and overall wellness, (If you purchase through links in this post, we may receive a commission.) but many people aren’t exactly sure what it does and how it connects to how they feel every day.

This diagram shows how the thyroid is linked to the entire body.

What Does Your Thyroid Do? Your Thyroid Health Determines Your Overall Health

The Problem with Low Thyroid Hormone

Low thyroid function, or hypothyroidism, is the most common form of thyroid imbalance. Some studies estimate that 90% of Americans suffer from undiagnosed thyroid dysfunction. Women often look to functional medicine or holistic doctors because they’re experiencing these symptoms but have been told by their conventional doctors that “everything looks fine.” The fact is, thyroid-related issues can arise at any age and may not necessarily show up on routine lab tests.

Centrally located at the base of the throat, the butterfly-shaped thyroid gland maintains the overall balance between the brain and the rest of the body.

Its hormones affect many systems and functions, including:

  • Metabolism
  • Brain development
  • Breathing, heart, and nervous system function
  • Blood cell production
  • Muscle and bone strength
  • Body temperature
  • Menstrual cycles
  • Libido and fertility
  • Weight gain and loss
  • Cholesterol levels
  • Skin hydration

It makes sense that when your thyroid isn’t functioning correctly, your life can seem significantly off-kilter, even downright miserable.

The primary thyroid hormones, thyroxine (T4) and triiodothyronine (T3), influence every cell’s metabolism in our bodies; T4 is a precursor to T3, the biologically active form of the thyroid hormone used in the cells. T4 is produced in the thyroid and converted into T3 in the liver and kidneys.

The conversion process of thyroid hormone involves a series of events. First, when T3 and T4 are low in the bloodstream, the part of your brain known as the hypothalamus – the “command center” for most hormones – sends a message in the form of TRH (thyrotropin-releasing hormone) to the pituitary gland.

The pituitary gland then interprets the message to secrete more TSH (thyroid-stimulating hormone), which in turn prompts your thyroid gland to take up iodine and the amino acid tyrosine to produce more T3 and T4. The T3 produced in the thyroid is a small amount used for short-term energy requirements. As a result, the thyroid produces more T4, which is converted to T3 in the liver and gut, then used in the cell by mediating T3 cell receptors outside the cell membrane, which “read” the T3 and allow it to enter the cell.

The Hypothalamus- The Hormone Command Center

Thus, there are three main areas where dysfunction can occur: 

1) The hypothalamus/pituitary/thyroid production of T4 – The production and release of thyroid hormones are run by a feedback system that includes the thyroid gland, the pituitary gland, and the hypothalamus. When this feedback loop is disrupted, the result is either too much or too little thyroid hormone.

2) The conversion of T4 to T3 -The liver and the gut are where most of the conversion of T4 to T3 happens. If you have low thyroid function, that will make the gallbladder and liver sluggish, thus slowing the conversion of T4 to T3. A sluggish liver also leads to high estrogen, affecting T4 to T3 conversions.

3) T3 receptors on the cell membrane (known as thyroid hormone resistance)- This rare genetic condition where body tissues don’t respond to thyroid hormones. Some patients have no symptoms, while others are resistant or sensitive to high thyroid hormone levels.

Let’s look at common thyroid imbalances:


When your thyroid hormones are too low to support your daily activities, it is known as hypothyroidism. Hypothyroidism can cause severe fatigue and loss of energy and libido, dry skin, hair changes, general puffiness, constipation, digestive problems, cold intolerance, depression, and more. It can also increase cholesterol levels and aggravate PMS, menstrual irregularities, and fibrocystic breasts. Sufferers of hypothyroidism also have a greater chance of developing diabetes and heart disease.

A common cause of hypothyroidism is an autoimmune disease called Hashimoto’s thyroiditis. 80% of newly diagnosed hypothyroidism is autoimmune and diagnosed by testing for thyroid antibodies. It is crucial to know whether your thyroid dysfunction is autoimmune based, as this drastically alters the treatment method and therapy used.


When the thyroid produces too much thyroid hormone, it is called hyperthyroidism. Too much thyroid hormone can cause nervousness and anxiety, increased heart rate or palpitations, breathlessness, diarrhea, insomnia, and depression. Like hypothyroidism, the most common cause of hyperthyroidism is an autoimmune disease called Graves’ disease. Chronic Graves’ disease may cause a person’s eyes to bulge (exophthalmos). 

Subclinical Hypothyroidism

When someone experiences hypothyroidism symptoms even though their thyroid test results are still in the “normal range,” it’s likely that their lab tests are at either end of the normal range. This result is called subclinical hypothyroidism. Despite having what’s considered “normal” lab test results, people in this category often feel much better when their thyroid function is enhanced. 

The question is….what to do about it?

The main factor to consider with thyroid disease is the root cause? Is it autoimmune-based or not? If so, it begs the question, why is your immune system attacking your thyroid? If not, what other factors must be considered to find the root of the problem?

We need to first understand inflammation. We are all familiar with the inflammation that comes with a cut or a wound but not with chronic inflammation.

Chronic inflammation, however, is altogether different

It is this same inflammatory process but a chronic one (long-term), located system-wide in the body and at the cellular level, affecting the cell membrane and the membranes of the cell organelles, such as the nucleus (home for DNA) and the mitochondria (producers of cell energy). This type of inflammation is deadly, disrupting healthy cell function at every level, and is known to be at the root of almost every western degenerative and autoimmune disease, including thyroid disease.

With this in mind, the real question now becomes:

What Does Your Thyroid Do?

Why is my thyroid inflamed?

The answer lies in understanding what causes chronic inflammation.

The leading causes of inflammation are:

Chemical toxicity-

The thyroid is extremely sensitive to toxic chemicals. These chemicals cause inflammation that disrupts thyroid function, causing our sex lives, reproductive health, metabolism, and mental health to suffer. Thousands of toxic chemicals are everywhere in our environment; food, heavy metals, biotoxins, personal care & cleaning products, pesticides, etc. 

Fluoride and mercury tooth fillings are also a problem. Studies on fluoride have shown no distinguishable health benefits and increased adverse health effects.

FYI: Doctors used fluoride to treat hyperthyroidism until the 1950s, before developing other thyroid-suppressing medications!

It takes 2.0 to 5.0 mg of fluoride a day to suppress an overactive thyroid.  

If you live in the typical fluoridated community and you’re drinking your 8 cups of water each day, chances are, you are unknowingly taking in enough fluoride to suppress your thyroid. Most adults in these communities are ingesting between 1.6 and 6.6 mg of fluoride per day without knowing the harm they are causing their thyroids.

According to Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City, studies show that iodine deficiency may result from higher ingestion of fluoride, causing hypothyroidism. He also stated, “drinking water is fluoridated in the United States, where hypothyroidism is a highly prevalent disorder — affecting over 15 million individuals mainly female and greater than 40 years old.”

Another chemical for concern is PFAS (per- and polyfluoroalkyl substances). These chemicals prevent grease and oil from seeping through food wrappers and are found in the bodies of everyone over 12 years old in the U.S. There are over 5,000 types, and of the ones studied, there are links to cancers, infertility, high cholesterol, weakened immune systems, hormone changes, and low birth weights in infants.

PFOA (Perfluorooctanoic Acid) is also a problem. Studies found this chemical increases risk of tumors of the liver, testicles, breasts, and pancreas. This chemical is in Teflon-coated cookware, fabric protectors, stain-resistant carpet, water-repellent clothes, packaging, ski wax, and fire fighting foams.

These are 3 of the thousands of toxins in our environment that cause inflammation. There are hundreds more. Many studies have linked inflammation to the rise in autoimmune diseases.

With autoimmune diseases, your body’s defense system triggers inflammation when there are no invaders to fight off. Your immune system acts as if normal tissues are infected or somehow unusual in these diseases, causing damage.

We know inflammation is short-lived (acute) or long-lasting (chronic). Acute inflammation goes away within hours or days. Chronic inflammation can last months or years, even after the first trigger is gone. Conditions linked to chronic inflammation include infection or injury, an autoimmune disease, long-term exposure to industrial chemicals, or pollution.

Chronic inflammation has links to these diseases:

  • cancer
  • heart disease
  • rheumatoid arthritis
  • type 2 diabetes
  • obesity
  • asthma
  • neurodegenerative diseases, such as Alzheimer’s disease

 Additional factors contributing to chronic inflammation include stress, unresolved trauma, smoking, obesity, and alcohol abuse.

If your thyroid is not functioning as it should, there are actions you can take to help your thyroid and your whole body feel better.

Feed Your Thyroid!

#1. Feed your thyroid

Food plays an essential role in everyday thyroid function and in eliminating inflammation. First of all, make a point of eating breakfast every day so that your system gets a balanced start. Keep sweets and simple starches to a minimum (eliminate if you can). Even natural sweeteners like maple syrup and honey use insulin to metabolize and are inflammatory. Make sure you get enough protein as well. Too many carbs and too little protein can interfere with the conversion of T4 into T3.

Your thyroid also requires specific nutrients for proper functioning, such as iodine, selenium, other minerals, tyrosine, and B vitamins. These nutrients are available in seafood, sea vegetables, poultry, Brazil nuts, mushrooms, legumes, yogurt, strawberries, and eggs. However, caution: do not supplement with iodine if you have autoimmune thyroid disease. Your thyroid uses iodine to make thyroid hormones, so too much may worsen your symptoms.

#2 Support your thyroid

Herbs and minerals to support healthy thyroid function: Herbs like ashwagandha, hops, sage, bacopa monnieri, coleus, and guggul can also help support thyroid hormone production and balance hormonal signals to the thyroid gland, thus boosting energy and protecting other functions in the body. 

There are a few nutrient deficiencies common with hypothyroidism:

Vitamin B12- Vital for thyroid production; it boosts cell response and increases energy to help with fatigue.

Selenium- Helps with metabolism, and studies have shown a reduction of thyroid antibodies in Hashimoto’s patients.

Zinc- benefits thyroid function and hormone levels. 

#3 Thyroid-healthy lifestyle changes: 

You might not expect that factors like managing stress, taking time for yourself, getting enough sleep, exercising regularly, and attending to emotional wellness would make a significant difference when it comes to thyroid health – but they can—plus, getting out in the sun for few minutes each day (to help maintain adequate vitamin D levels) and avoiding exposure to herbicides, pesticides, and cigarette smoke. These steps can also improve your adrenal glands’ health, as your adrenals are intimately connected to thyroid health.

Hopefully, you have a better understanding of “what does your thyroid do?”

I have included suggestions for improving your thyroid function, but this is not a replacement for proper medical care.

Take care,