The thyroid is a small butterfly-shaped gland located in the tissues of the neck just below the Adam’s apple area. It is considered a key player in our health. The thyroid produces and secretes essential hormones that regulate processes like body temperature, growth, energy storage and use (metabolism), heart rate, digestion, bone health, reproductive health, and more (1). Needless to say, when this is not working optimally, you will notice it. Let’s dive in more to understand the intricacies of this amazing gland.
Let's Dive Into Thyroid Hormones
T4 (tetraiodothyronine or thyroxine): This is the major thyroid hormone produced, although it is “inactive” and must be converted to T3 to become beneficial.
T3 (triiodothyronine): The “active” thyroid hormone. This is responsible for what people often refer to as “boosting their metabolism”. It is like pushing on the gas pedal.
Reverse T3: The less talked about hormone. Reverse T3 is like pushing on the brake pedal as it stops T3 from working properly (2).
Calcitonin: This hormone is produced by the thyroid and helps the body regulate calcium levels in the blood. This is an important consideration when reviewing your standard labs which measures serum calcium.
Are you wondering---Isn’t TSH the thyroid hormone?
The scientific/medical answer is no. The pituitary gland, a leader of the endocrine system, releases thyroid stimulating hormone (TSH) to tell the thyroid to release its hormone (T4 and T3 specifically) (3). You can think of it this way:
TSH is like a teacher in a classroom telling the students to do their homework (TSH tells the thyroid to make hormones).
It is then up to the student (the thyroid gland) to decide if and how it is going to do the assignment (make the needed T4 and T3 hormones in the right amount).
Just like there are many factors that impact the student’s ability to complete the assignment, such as: 1) Did they hear the directive? 2) Do they understand the request? 3) Did internal or external things interfere with being able to do it? 4) Was the student proper nourished to think through the assignment…and much more. The thyroid’s function is impacted by many factors as well, including diet, the presence of key nutrients, stress, infection, activity, and toxins.
An Under Functioning Thyroid
Hypothyroidism is diagnosed by a medical provider and describes the thyroid gland as under-functioning (3). Symptoms of hypothyroidism include, but are not limited to, fatigue, increased cold sensitivity, hair loss, dry skin, unexplained weight gain/trouble losing weight, muscle weakness, hoarseness, morning headaches that dissipates over the course of the day, and a puffier appearance to the face. A lack of iodine, necessary for producing thyroid hormones, or exposure to in substances like fluoride, chlorine, and bromine that block iodine contribute to 95% of all hypothyroid cases in underdeveloped countries, but not the U.S. (3). Don’t rush out to get iodine just yet!
There are three main types of hypothyroidism, which require a different approach for care.
Primary hypothyroidism: Low levels of thyroid hormones are produced due to some type of destruction to the thyroid gland. The leading cause of primary hypothyroidism in the U.S. is an autoimmune condition known as Hashimoto's Thyroiditis. This is a result of the thyroid cells attacking themselves (4). This may cause someone to experience symptoms of both hypo and hyperthyroidism. Other things like radiation or surgery may also be a cause of primary hypothyroidism.
Secondary hypothyroidism is less common and refers to a lack of TSH being secreted from the pituitary gland resulting in a less active thyroid gland.
Tertiary hypothyroidism is also less common and is caused by a lack of thyroid-releasing hormone (TRH) being secreted from the hypothalamus in the brain, leading to less TSH being secreted by the pituitary and therefore less thyroid hormones being produced by the thyroid.
It is worth noting that almost 10% of women in general and up to 18% of women over the age of 60 may present with subclinical hypothyroidism. This means that TSH may be elevated, but T4 is normal (5).
The Importance of Thyroid Antibodies
Your doctor may use one or both tests to determine if Hashimoto’s thyroiditis is the cause of dysfunction in the thyroid.
Thyroglobulin (TgAb): Thyroglobulin is a protein made in the thyroid gland and generally stays there, but in some instances, it can leak into the bloodstream. An increased in this antibody can be a sign of damage being caused to the thyroid gland as a response by the immune system to this leaking.
Thyroid peroxidase antibodies (TPO): Thyroid peroxidase is an enzyme made in the thyroid gland. When this leaks into the bloodstream, the immune system responds, causing the TPO to increase.
It is important to know that your TSH, T4, and T3 levels may or may not be out of range when antibodies are present.
What do you do if your thyroid is not working as well as it should?
Stress, toxin exposures, infections, inflammation, some medications, nutritional deficiencies, and low-calorie diets are contributors to the potential development of hypothyroidism. Therefore, it is essential to ensure adequate nutrient density in the
the foods consumed to help overcome some of these contributors.
Consume an Anti-Inflammatory Food Plan
An anti-inflammatory diet incorporates vegetables, fruits, omega-3-rich fish and other quality poultry and meat, nuts & seeds. It will be rich in key nutrients needed for thyroid health, such as B vitamins, iodine, iron, selenium, zinc, magnesium, and vitamins A, C, and D. It is also focused on decreasing the amounts of foods that cause the body to respond by creating more inflammation- foods such as processed foods, soda, and conventionally grown produce that has been exposed to multiple pesticides. It is also helpful to reduce any foods that you suspect or know to be sensitive or allergic to, such as dairy and gluten. For individuals that have been diagnosed with Hashimoto’s thyroiditis, it is common to have one or more foods sensitivities and studies have found that adhering to a gluten-free diet may be most beneficial (6).
Iodine: Thyroid hormones are named for the number of iodine molecules on it. (T4=4 iodine molecules, T3=3 iodine molecules). Therefore, consuming small amounts of iodine will be beneficial to thyroid health. The recommended daily allowance is 150 mcg of iodine with a tolerable upper limit (TUL) of 1100 mcg (7). One excellent option is to choose fish as the primary source of protein multiple days per week. For example, one 3 ounce serving of haddock contains up to 145 mcg of iodine (7). Other sources of iodine include dulse-sea algae that can be sprinkled on food in place of salt or consumed as seaweed snacks. Iodized salt can also be considered. It is important to note that those taking the pharmaceutical Synthroid for management of thyroid, those who have been diagnosed with Hashimoto’s, or those who are not sure if they have Hashimoto’s should speak to their doctor before increasing iodine beyond the RDA amount or taking it in supplement form as it may increase thyroid production to an unsafe level or contribute to an increased autoimmune attack on the thyroid (8).
Zinc: Zinc is a nutrient that is needed to produce T4, support the conversation to T3 (rather than Reverse T3) and then help T3 bind to receptor sites on the cells for utilization in bodily functions. Adequate zinc intake also helps to protect against thyroid antibodies (6). Zinc is most abundant in oysters, should you be a fan! If not, meat, poultry, seafood, whole grains, flax seeds, pumpkin seeds, and legumes are nice alternatives (10).
Selenium: Selenium is a nutrient that is necessary to help the thyroid hormone T4 create the active form of T3. In a recent study, consuming at least 55 mcg of selenium was shown to normalize T4 and T3 levels (11). Brazil nuts are an ideal source of selenium, coming in at a whopping 68-91 mcg for just one nut! Adding these nuts as a snack or to top a salad is a way to ensure a nutrient-dense and anti-inflammatory diet that supports thyroid health. NOTE: This is a nutrient that is part of the “Goldilocks Rule”, meaning not too little and not too much, just the right amount is needed. Therefore, aim to just have one Brazil nut per day and know that you will get selenium from other food sources on the anti-inflammatory food plan.
Please note that this is not an exhaustive list of potential foods or nutrients needed to manage thyroid health. Consider supplementation as needed. See the blog: Top 10 Supplements for Underactive Thyroid and work with your nutritionist to develop a plan that is best for you.
Let's Discuss The Elephant in the Room
You may have heard that if your thyroid is not working well, you should avoid certain vegetables like broccoli, cauliflower, kale, and other cruciferous veggies. This is misleading.
While cruciferous vegetables contain a compound known as goitrogens, that some suggest block the receptor site for iodine, preventing its uptake, the avoidance of these vegetables would be more detrimental than beneficial. Cruciferous vegetables are beneficial for detoxification and hormone balance. Plants need iodine in their metabolism, therefore, as a result, you get very little of that iodine when you eat the plants. Further, the volume you would need to consume is almost impossible. For example, you would have to consume over 4 pounds of broccoli every day for it to interfere with thyroid function (9)!
If you are concerned about intake, one way to navigate this perceived barrier is to lightly steam Brussels sprouts, cauliflower, broccoli, and kale, which essentially inactivates the goitrogens while leaving the many nutrients intact.
Reduce Toxic Exposures
Let’s go back to high school chemistry class. Remember the periodic table?
Iodine is lined up with fluoride, chloride, and bromine, meaning that these compounds will interfere with the utilization of iodine and therefore impact thyroid function. It can be helpful to review where these might be coming into your diet or environment, such as fluoride toothpaste, fluoride and chlorine in water sources, bromine is popular in many sodas and energy drinks, and chlorine can be found in some artificial sweeteners and exposure can be high for those who regularly use a hot tub or swimming pool. See the blog: Lifestyle Solutions for Thyroid Health for more helpful tips on reducing toxic exposures.
Get Moving
It can be a big challenge and seem almost impossible to consider exercise when your thyroid is not working optimally. But exercise is a critical factor in helping T3 bind to the receptor sites on your cell—allowing you to “push on your gas pedal” more. See the blog: Lifestyle Solutions for Thyroid Health for more on this topic.
Managing Stress
The thyroid gland is part of the endocrine system and the hypothalamus-pituitary-thyroid-adrenal-gonadal (HPTAG) axis. In short, what happens in the thyroid doesn’t stay in the thyroid! In fact, adrenal health (or dysfunction) may be a contributing factor to altering thyroid health. The adrenal glands are responsible for responding to and managing stress. Stress can inhibit T4 production and encourage the conversion to reverse T3 (the brake pedal). We have multiple blog posts talking about the various forms of stress management you might want to explore.
Conclusion
Overall, after years of clinical practice, we have found that understanding the intricacies of how the thyroid works is a key starting point. Then supporting the thyroid with diet, nutrients, supplements (as indicated), increasing movement, maintaining a healthy environment to reduce toxin exposures, and managing stress helps improve outcomes.
It is best to collaboratively work with your healthcare providers, including your nutritionist, primary care physician, and endocrinologist to develop the right plan for your unique needs.
Be sure to check out our additional blogs for more information:
Top 10 Supplements for Thyroid Health: Coming Soon!
Lifestyle Solutions to Support Thyroid Health: Coming Soon!
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Written by Kimberly King, MS and Kim Ross, DCN
Last reviewed and updated July 23, 2024
The information provided is for educational purposes only and is not intended to replace the guidance of your healthcare provider(s).
References
1. Armstrong M, Asuka E, Fingeret A. Physiology, Thyroid Function. In: StatPearls. Treasure Island (FL): StatPearls Publishing; March 13, 2023.
2. Wilson JB, Friedman TC. Reverse T3 in Patients With Hypothyroidism, Helpful or a Waste of Time? J Endocr Soc. 2021;5(Supplement_1). doi:10.1210/jendso/bvab048.1945
3. Rakel D. Integrative Medicine. 5th ed. Elsevier; 2023.
4. Mincer, D., & Jialal I. Hashimoto’s Thyroiditis. [Internet]. StatsPearls Publishing; 2020.
5. Chaker L, Bianco AC, Jonklaas J, Peeters RP. Hypothyroidism. The Lancet. 2017;390(10101):1550-1562. doi:10.1016/S0140-6736(17)30703-1
6. Danailova Y, Velikova T, Nikolaev G, et al. Nutritional Management of Thyroiditis of Hashimoto. Int J Mol Sci. 2022;23(9). doi:10.3390/ijms23095144
7. National Institutes of Health Office of Dietary Supplements. Iodine-Fact Sheet for Healthcare Professionals. National Institute of Health Office of Dietary Supplements. Published April 28, 2022. Accessed July 22, 2024. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
8. Wiesner A, Gajewska D, Paśko P. Levothyroxine interactions with food and dietary supplements–a systematic review. Pharmaceuticals. 2021;14(3). doi:10.3390/ph14030206
9. Felker P, Bunch R, Leung AM. Concentrations of thiocyanate and goitrin in human plasma, their precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism. Nutr Rev. 2016;74(4):248-258. doi:10.1093/nutrit/nuv110
10. National Institutes of Health Office of Dietary Supplements. Zinc Fact Sheet for Health Professionals. National Institutes of Health Office of Dietary Supplements. Published September 28, 2022. Accessed September 26, 2023. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
11. Hu W, Zhao C, Hu H, Yin S. Food sources of selenium and its relationship with chronic diseases. Nutrients. 2021;13(5). doi:10.3390/nu13051739