What You Need to Know About Your Thyroid Health

Fact Checked

thyroid glands

Story at-a-glance

  • The thyroid gland is a butterfly-shaped gland found inside your neck, right under your larynx or voice box
  • Your thyroid is responsible for producing hormones that control vital functions in your body
  • Hypothyroidism occurs when your thyroid produces too little thyroid hormone, a condition that is often linked to iodine deficiency. Hyperthyroidism is the opposite, wherein your thyroid produces too many hormones


This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

Your thyroid, one of your most important endocrine glands, greatly influences almost every cell in your body. Aside from regulating your metabolism by releasing the necessary hormones, the thyroid is also important for the growth and development in children, as well as nearly every physiological process in your body.1

When your thyroid levels are out of balance, so are you. Too much (hyperthyroidism2) or too little (hypothyroidism3) hormone secretion can spell trouble for your overall health.

A 2018 study noted that 0.3% to 3.7% of the general U.S. population suffer from hypothyroidism, although it could be as high as 15% if you count a type of "subclinical" hypothyroidism. On the flip side, 0.5% of the population have hyperthyroidism.4

Poor thyroid function has been linked to health conditions such as fibromyalgia,5 irritable bowel disease,6 vitiligo,7 gum disease,8 infertility in women9 and autoimmune diseases,10 which is why it's imperative to learn how your thyroid works and what can cause it to go off-kilter.

The Thyroid Gland: Understanding How It Works

The thyroid gland is a butterfly-shaped gland found inside your neck, right under your larynx or voice box. It has two lobes on each side of the windpipe that are connected by a tissue called the isthmus.11 A normal thyroid gland weighs somewhere between 20 and 60 grams (0.7 to 2.1 ounces).12

Your thyroid is responsible for producing the master metabolism hormones that control every function in your body. It produces two hormones:13

  • Triiodothyronine (T3)
  • Thyroxine (T4)

Hormones secreted by your thyroid interact with your mitochondria, causing "an increase in nutrient breakdown and production of ATP."14 The fact that these hormones play important roles throughout your body explains why a less-than-optimal thyroid status is associated with many widespread symptoms and diseases.

Almost 90% of the hormone produced by your thyroid is in the form of T4, the inactive form.15 Your liver then converts the T4 into T3, the active form, through deiodination.16

If everything is working properly, you will make what you need and have the correct amounts of thyroid hormones, which control the metabolism of every cell in your body.17 If your T3 is inadequate, either by scarce production or by not converting properly from T4, your whole system suffers. T3 is critically important because it plays a role in burning fat in your body. In one study, researchers noted that when they increased T3 levels in participants, weight loss occurred.18

Your thyroid hormone levels can be disrupted by various risk factors. The National Institute of Diabetes and Digestive and Kidney Diseases outlines the following possible factors for both hypothyroidism and hyperthyroidism:19,20

Hypothyroidism Hyperthyroidism

Age (more common among people 60 years old and above)

Age (more common among people 60 years old and above)

History of thyroid problems, such as goiter, and thyroid surgery

Have a disease such as Type 1 diabetes, pernicious anemia or primary adrenal insufficiency

History of radiation treatment to thyroid, neck or chest

Eating foods with large amounts of iodine, or drinking medicine that contains iodine

Pregnant in the past six months

Pregnant in the past six months

Have a disease such as Turner syndrome, Type 1 diabetes, lupus, rheumatoid arthritis and pernicious anemia

Hypothyroidism: The Sluggish Thyroid Syndrome

Hypothyroidism occurs when your thyroid produces too little thyroid hormone, a condition often linked to iodine deficiency.21 Dr. David Brownstein, a board-certified holistic practitioner who has been working with iodine for the past two decades, claims that over 95% of the patients in his clinic are iodine-deficient, as stated in his book "The Soy Deception."22

In addition, a study published in 2012 estimates that 4.3% to 8.5% of the population has subclinical hypothyroidism,23 a condition wherein you seemingly have normal thyroid levels but "serum thyroid-stimulating hormone (TSH) levels are mildly elevated."24

However, only a marginal percentage of people with subclinical hypothyroidism are being treated. The reason behind this is the interpretation of lab tests, particularly TSH. Most physicians believe that if your TSH value is within the "normal" range, your thyroid is fine and you don't need treatment.

But as the saying goes, the devil is in the details. If your doctor suspects that the TSH levels may be slightly elevated even if the tests don't indicate such, treatment may be started early to help prevent the subclinical condition from becoming overt.25

How to Know if You Have Hypothyroidism

Identifying hypothyroidism and its cause can be tricky. Many of the symptoms of hypothyroidism are vague and may be confused with other disorders. Physicians often miss a thyroid problem since they rely on just a few traditional tests, leaving other clues undetected.

The most sensitive way to find out is to simply pay attention to signals from your body. According to InformedHealth.org, people with a sluggish thyroid usually experience diverse indicators, such as:26

  • Fatigue and lethargy
  • Sensitivity to cold temperatures
  • Slight to moderate weight gain
  • Shortness of breath during exercise
  • Problems concentrating
  • Constipation
  • Hair loss and dry skin
  • Hoarse voice
  • Depression
  • Heavy menstrual bleeding or other menstrual problems in women
  • Muscle or joint pain
  • Slow reflexes

Any of the mentioned symptoms can be suggestive of an underactive thyroid. The more of these symptoms you have, the higher the likelihood that you have hypothyroidism. Furthermore, the Mayo Clinic notes that if the disease is left untreated, it may lead to more health complications, such as:27

  • Goiter
  • Increased risk of heart disease
  • Infertility
  • Birth defects for pregnant women
  • Damage to peripheral nerves
  • Increased severity of mental health problems, such as depression
  • Myxedema, a severe form of hypothyroidism that may result in "cardiogenic shock, respiratory depression, hypothermia and coma"28

The more vigilant you are in assessing your own symptoms and risk factors and presenting the complete picture to your physician, the easier it will be for you to get the proper treatment.

How About if You Have a Hyperactive Thyroid?

Thyroxine or T4 is a hormone made by the thyroid gland and converted into T3 through deiodination. Many of your cells and tissues depend on these hormones to work properly.29

An overactive thyroid secretes too much T4 or T3 (sometimes both),30 causing some of your body functions to accelerate. This condition is hyperthyroidism, wherein your thyroid overproduces hormones. According to a 2016 study published in The Lancet, women are more susceptible to this condition.31 Hyperthyroidism may manifest in different ways, according to the Lancet study:32

  • Palpitation
  • Fatigue
  • Tremors
  • Anxiety
  • Disturbed sleep
  • Weight loss
  • Heat intolerance
  • Polydipsia (excessive thirst33)

Some of these symptoms may be unnoticeable, depending on factors such as your age and underlying cause. A study in the American Family Physician explains that elderly patients may have hyperthyroidism, but diagnosing may be harder because symptoms are less apparent, which may lead to complications.34 Untreated hyperthyroidism can lead to heart problems like atrial fibrillation, cardiomyopathy, angina and heart failure.35

Diagnosing Possible Thyroid Issues

There are several ways to diagnose an underactive or hyperactive thyroid. The following laboratory tests are what most professionals use to get the real score of your thyroid health:

  • Serum TSH test — A blood test that measures your TSH levels. Results that indicate too high or too low levels may indicate abnormal thyroid function.36
  • T4 test — Your doctor may order a test that checks both free and bound T4 levels. Free T4 is the hormone that's "freely" running through your bloodstream, while bound T4 refers to ones that have already "bonded" to proteins.37
  • Thyroid antibody testing — This test looks for antibodies that target thyroid peroxidase, thyroglobulin and TSH receptors.38
  • Body temperature checks — According to Dr. Denis Wilson, who was the first doctor to use sustained release T3 thyroid hormone in a 2015 study, low body temperature may be a possible indicator for poor thyroid function.39
  • Radioactive iodine uptake — Ingesting a small amount of radioactive iodine may help determine thyroid function. Results that show high uptake may indicate hyperthyroidism. Low uptake may suggest hypothyroidism.40

Other tests that may help with your diagnosis are a thyroid scintigraphy,41 fine-needle aspiration42 and thyroid ultrasound.43 But these are specialized tests that your physician will use only in a small number of cases or in special situations.

Are You at Risk of Thyroid Cancer?

The American Cancer Society predicts that around 52,070 new cases and 2,170 deaths from thyroid cancer will occur in the United States alone in 2019.44 Thyroid cancer is classified into five different types: papillary, follicular, Hürthle cell (these three are called the differentiated thyroid cancers), medullary and anaplastic.45

Just like with any type of cancer, early intervention may heighten your chances of remission and recovery. This is why you should always be on the lookout for symptoms. Below is a list of potential warning signs of thyroid cancer, according to a 2015 study:46

  • The presence of thyroid nodules
  • Swelling in front of the neck
  • Breathing problems
  • Hoarseness or other changes in voice
  • Difficulty swallowing

In addition, there are certain risk factors that may predispose you to this disease. These include:

  • Gender — Females are more susceptible to developing thyroid cancer compared to men.47
  • Weight — Researchers discovered a correlation between obesity and increased incidences of thyroid cancer, but the connection has yet to be clearly established.48
  • Family history — A family history of thyroid cancer increases your risk of thyroid cancer, which triples with first-degree relatives who developed the disease.49
  • Iodine deficiency — A 2017 meta-analysis concluded that increasing iodine intake may help protect your health from thyroid cancer.50
  • Environment — One study concluded that exposure to various chemical pollutants such as polychlorinated biphenyl (PCB), bisphenol A and phthalates may increase the risk of thyroid cancer.51

4 Things That Affect Your Thyroid Health

These are some key contributing factors that can ruin your healthy thyroid function:

1. Gluten Gluten is a notorious culprit of thyroid dysfunction, as it can cause inflammation and autoimmune responses in many people, and can be responsible for Hashimoto's thyroiditis.52

Gluten sensitivity can cause your gastrointestinal system to malfunction, so foods you eat aren't completely digested, which may lead to leaky gut syndrome, allowing bacteria and other toxins to enter your bloodstream.53 This connection becomes more apparent as one study highlights a connection between autoimmune thyroiditis and celiac disease,54 a gluten-related autoimmune condition that damages your small intestines.55

Chris Kresser, an integrative medicine practitioner, recommends The Gluten-Free Challenge. This involves completely removing gluten from your diet for at least 30 days, and then adding it back right after. He explains:56

"If symptoms improve during the elimination period, and return when gluten is reintroduced, a diagnosis of non-celiac gluten sensitivity (NCGS) can be made."

2. Soy — As I've mentioned so many times before, soy is not the wholesome health food the agricultural and food companies have led you to believe. There are studies explaining the danger of soy foods such as their antinutrients,57 impact on digestive health58 and goitrogens that affect thyroid function.59

Properly or traditionally fermented, organic and unprocessed soy products such as natto, miso, and tempeh are fine — it's the unfermented soy products you should stay away from, like soy "meat," soy milk and soy cheese. To know more about soy, read "Soy — Health Food or Not?"

3. Bromine — Bromine is a common endocrine disruptor60 found in fire retardants. Evidence shows that this compound may affect proper thyroid function, as well as hormone transport.61

When you ingest or absorb bromine, it displaces iodine, and this iodine deficiency leads to an increased risk for cancer of the breast, thyroid gland, ovary and prostate cancers that we see at alarmingly high rates today. This phenomenon is significant enough to have been given its own name: the Bromide Dominance Theory.62

In addition, when food becomes contaminated with bromine, it may cause nausea and vomiting.63 Bromine can be found regularly in a number of places, including:

  • Pesticides for agricultural applications64
  • Plastics such as those used to make common consumer products65
  • Bakery products such as flour66
  • Soft drinks that have citrus flavor — in the form of brominated vegetable oils (BVOs)67
  • Swimming pools as an alternative to chlorine68
  • Fire retardants to prevent fires from occurring69

To achieve the best thyroid health possible, proper lifestyle changes are needed. I strongly recommend that you avoid products and environments that can expose you to bromine.

4. Stress and adrenal function — Stress is one of the worst thyroid offenders. Your thyroid function is intimately tied to your adrenal function, which is affected by how you handle stress.70

Many of us are almost always under chronic stress, which results in increased adrenal stress hormones71 and cortisol levels — and elevated cortisol has a negative impact on thyroid function.72 Thyroid hormone levels drop during stressful times, and affect the function of the HPT axis.73

When stress becomes chronic, the flood of stress chemicals — adrenaline and cortisol — produced by your adrenal glands interfere with your thyroid hormones, causing a whole gamut of health-related issues like obesity,74 high blood pressure75 and high LDL cholesterol.76 It also affects your glucose metabolism.77

For tips to better manage stress, I recommend you read my article "How Stress Affects Your Body, and Simple Techniques to Reduce Stress and Develop Greater Resilience."

Iodine: Your Best Weapon Against Thyroid Problems

Iodine is perhaps the biggest piece of the puzzle when it comes to thyroid hormones. It's an important nutrient found in every organ and tissue. It's essential for healthy thyroid function and efficient metabolism,78 and evidence shows that low iodine levels relate to numerous diseases, including cancer.79

Iodine is a potent antibacterial80 and antiviral81 agent. It has other significant roles in your body, namely to maintain proper metabolic function, develop brain and cognitive function in children and strengthen your immune system.82 Though thyroid health is often associate with iodine, deficiency in this nutrient can affect human biology in several ways. Some noteworthy examples include:

  • Cretinism — This is a form of intellectual disability documented in children, along with other symptoms such as dwarfism.83
  • Goiter — One study shows that inadequate iodine levels may lead to nontoxic nodular goiter.84
  • Pregnancy problems — One study shows that iodine deficiency may lead to pregnancy-related complications such as stillbirths, congenital anomalies and increased infant mortality.85

The Total Diet Study, performed by the FDA, reported an iodine intake of 621 micrograms for 2-year-olds between 1974 and 1982, compared with 373 micrograms between 1982 and 1991.86 One probable reason for the reduced iodine intake through the years is its disappearance from our food supply because of iodine-deficient soil.87

Exposure to toxic compounds I've mentioned before — brominated products, fire retardants and other toxins — has dramatically increased as well. Here are more factors contributing to falling iodine levels:

  • Diets low in fish, shellfish and seaweed
  • Vegan and vegetarian diets88
  • Fluoridated drinking water89
  • Rocket fuel (perchlorate) contamination in food90
  • Decreased use of iodized salt91

How to Increase Your Iodine Levels Naturally

Sadly, up to 30% of the population worldwide could be at risk for iodine deficiency.92 In fact, iodine deficiency is one of the three most common nutritional deficiencies, along with iron93 and vitamin D.94 Here are some helpful strategies to increase your iodine levels naturally:

  1. Eat organic as often as possible. Wash all produce thoroughly to minimize your pesticide exposure.
  2. Avoid eating or drinking from (or storing food and water in) plastic containers. Use glass and safe ceramic vessels.
  3. If you have to eat grain, look for organic whole grain breads and flour. Grind you own grain, if possible. Look for the "no bromine" or "bromine-free" labels on commercial baked goods.
  4. Avoid sodas. Make natural, filtered water your beverage of choice.
  5. If you own a hot tub, look into an ozone purification system. Such systems make it possible to keep the water clean with minimal chemical treatments.
  6. Look for personal care products that aren't laced with toxic chemicals. Remember: Anything you put on your skin can potentially go into your bloodstream.
  7. When in a car or a building, open windows as often as possible, preferably on opposing sides of the space for cross ventilation. Utilize fans to circulate the air. Chemical pollutants are in much higher concentrations inside buildings (and cars) than outside.

If you suspect that you are iodine-deficient, I strongly encourage you to visit your health care provider to undergo iodine testing. You can also get an affordable prescription for SSKI (super-saturated potassium iodine), which you apply on your skin once a day.

If when you touch something with slightly wet fingertips and you see a yellowish stain, it means the iodine is coming out of your skin, indicating that your body has enough supply of iodine inside. Read more about it in this article, "Iodine Supplements May Be Too Much of a Good Thing."

Simple Steps You Can Do to Improve Your Thyroid Health

Here are simple ways that you can take in order to improve the performance of your thyroid:

  • Identify and treat the underlying causes — Find out what's really triggering your thyroid problems — whether it's iodine deficiency, hormone imbalance, environmental toxicity or inflammation — to address it appropriately. For best results, consult an integrative medical practitioner.
  • Load up on fresh iodine-rich foods — As an alternative to iodine supplementation, eat toxin-free seafood such as seaweed, sardines and Alaskan salmon. However, make sure that these are harvested from uncontaminated waters. Eggs and dairy products such as grass fed milk, yogurt and cheese contain iodine as well.95
  • Avoid gluten — A 2019 study stated that avoiding gluten, or undergoing a gluten-free diet may benefit your thyroid, especially to those who have autoimmune thyroid disease.96
  • Minimize your stress levels — Take a break, meditate, soak in the tub, go on vacation — do whatever works for you. Practice Emotional Freedom Techniques (EFT), an energy psychology tool that can help reduce stress. A 2011 study noted that stress affects the hypothalamic-pituitary-thyroid (HPT) axis, which plays a role in hormone secretion.97
  • Make an effort to limit your exposure to toxins — As mentioned earlier, exposure to environmental pollutants may increase your risk of thyroid cancer. Examples include BPA and phthalates.98
  • Avoid all sources of bromine as much as possible — Bromines are a menace to your endocrine system and are present all around you. Despite a ban on the use of potassium bromate in flour by the World Health Organization, bromines can still be found in some over-the-counter medications, foods and personal care products. Being a savvy reader of labels can save you from tons of toxic trouble.
  • Get adequate amounts of sleep — Inadequate or low-quality sleep can put your health at risk. A study published in the American Journal of Epidemiology notes that participants "with greater insomnia scores, especially non-obese women, had a significantly increased risk of thyroid cancer."99 For more helpful tips on getting high-quality sleep, please review my "Top 33 Tips to Optimize Your Sleep Routine."
  • Exercise — Research shows that getting regular exercise may help reduce the risk of cancer.100 Walk your dog in the park, jog in the morning and incorporate strength training and other core-building routines. You can also check out my updated Fitness Plan for a comprehensive workout guide.


+ Sources and References

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