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Piecing Together Thyroid Health and Autoimmune Conditions

Piecing Together Thyroid Health and Autoimmune Conditions

piecing thyoid health

Why Selenium is Important for Thyroid function

Selenium plays a vital role in protecting the thyroid gland.  In the thyroid, iodine and tyrosine (an amino acid) are joined together by a protein (thyroglobulin) to form thyroid hormone T4 (thyroxine).  During this process, substantial amounts of free radicals are generated as hydrogen peroxide (H202).   These free radicals are then neutralized by an antioxidant, glutathione peroxidase (a type of selenocysteine enzyme: selenium-containing amino acid), that protects thyroid cells from oxidative damage.  However in the absence of selenium not only is the conversion of T4 to active T3 disrupted but unprotected thyroid cells are damaged from the excess H202 that's produced when the thyroid hormone T4 is created.  The immune system is structured in such a way to protect cells from oxidative damage, in this case damage caused by excess H202, this reaction is called an autoimmune response.

An Autoimmune Response

Repairing the damaged thyroid tissue requires the immune system to send T-lymphocytes (a category of white blood cells) as antibody-dependent cell-mediated cytotoxicity (ADCC) to the affected area in response to the helper T cells which then produce T cell cytokines.(1)  These cytokines help regulate the immune processes by causing an inflammatory response as a defense against extracellular microbes.(2)  When uptake of iodine progressively stimulates synthesis of T4 and selenoproteins are not present, the autoimmune response continues to send lymphocytes into the thyroid tissue and inflammation ensues.  While the thyroid gland becomes more damaged, thyroid hormone production becomes insufficient. Sensing this insufficiency as a low thyroid hormone level the pituitary gland secretes more thyroid stimulating hormone (TSH) which works to increase thyroid hormone production.  As TSH rises, the thyroid gland works even harder to uptake iodine from anywhere it can (including reserves like muscles and organs) to produce thyroid hormones.   Thyroid hormones then release free radicals into the endocrine system and damage to the thyroid gland continues as a result of these nutrient deficiencies-especially of selenium and/or iodine, respectively.  Additionally, while TSH stimulates thyroid hormone production, a goiter forms as a result.(3)  The thyroid gland grows in size (enlarged thyroid) to make an attempt to collect more iodine from the bloodstream; this compensation for deficiency in iodine causes the goiter to form. Goiters are often common in those who have Hashimoto's disease.  However, another common cause of a goiter may occur from Graves' disease where the immune system produces a protein called thyroid stimulating immunoglobulin (TSI) which stimulates the thyroid to make too much thyroid (hyperthyroidism) and causes the pituitary gland to stop secreting TSH.  The most common cause of goiters all over the world is iodine deficiency.(4)

Nearly 200 years ago, it was shown that the cause of goiter was iodine deficiency and the treatment of goiter required the use of iodine...over 96% of our patients are iodine deficient.
— David Brownstein, M.D. "Overcoming Thyroid Disorders"

Hypothyroidism and Hyperthyroidism as a Result of Autoimmune Disease

Hypothyroidism is a condition that occurs when the thyroid is unable to produce sufficient thyroid hormone.  Typically, Hashimoto's disease forms as a result of high TSH and low T4 levels.  Hyperthyroidism may also be a byproduct of Hashimoto's where the thyroid is over functioning by producing too much thyroid hormone.  However, it is important to understand that if the thyroid gland functions as both hypothyroidism (primarily) and hyperthyroidism (intermittently), antibodies will continue to decrease thyroid function ultimately as hypothyroidism.  

Alternatively, another autoimmune disorder, Graves' disease, typically causes the thyroid gland to become overactive (hyperthyroid) and as a result too much thyroid hormone is produced.(5)  In Graves' disease, the thyroid stimulating immunoglobulin (TSI) antibodies produce excess thyroid hormone as an autoimmune response which stimulates the hypothalamus to release TSH.  TSH signals to the thyroid to produce more T4 as a result.  Typically, Graves' disease forms as a result of elevated thyroid hormones (T3 and T4), low TSH, and TSI antibodies. 

When individuals are diagnosed with hypothyroidism, supplemental thyroid is typically used as a treatment in the form of either desiccated thyroid T4/T3 combination (Armour Thyroid, Nature-Throid, etc.) or synthetic T4 (Synthroid, Levothyroid, etc.).  Hypothyroidism as a result of an autoimmune disease, Hashimoto's thyroiditis, may continue to go undetected unless additional testing for thyroid peroxidase antibodies (TPOAb) is performed.

Selenium supplementation has show a reduction in TPO (thyroid peroxidase) antibodies in several studies. (6,7,8)

Selenium and Metabolism

As previously mentioned selenium also functions to activate and deactivate T4.  The active form of T4 is T3 (triiodothyronine), the hormone responsible for the rate of metabolic function (metabolism).  Metabolism increases the rate at which cellular functions occur, including: heart rate and blood pressure (autonomic nervous system); fats used for energy (fatty acid catabolism and anabolism); glucose released into the bloodstream (ATP); energy consumption (thermogenesis); skin texture; cell growth and division; and development and reproduction. 

While thyroid hormones are responsible for many of the endocrine system responses, they are also closely tied with mood, body weight, and energy expenditure.(9)  Many individuals who are concerned about weight gain and have hypothyroidism may seek thyroid replacement specifically for weight loss; however, studies indicate that the common thyroid replacement of T4 (without diet change) caused weight loss primarily in water weight and not fat mass.(10)  Fortunately, recent studies compared the use of T3 to T4 for hypothyroidism where thyroid replacement T3 demonstrated much greater results for weight-loss in fat mass as well as a reduction of total cholesterol.(11)  Interestingly enough, this also supports the evidence that deficiency in selenium leads to hypothyroidism where the conversion of T4 to T3 (removal of an iodine atom by selenium-based enzymes) is insufficient.  Replacement of T4 would be important for those who have a deficiency in iodine, but not those who have a deficiency in selenium.  However, an imbalance of either may also cause a deficiency in one as well as the other.  This is why it's so important to have a proper balance of both selenium and iodine to effectively support thyroid function.  This is discussed with more detail below in The Iodine-Selenium Connection

Here is a quick run-through of how metabolism and thyroid hormones are connected with results to improper function of the thyroid gland.

Hyperthyroidism, overactive thyroid producing excess thyroid hormone (T4, T3)

  • Very high metabolic rate (hypermetabolic state)
  • Rapid heartbeat
  • Raised blood pressure
  • Heat sensitivity
  • Irregular menstrual cycles
  • Weight loss
  • Frequent bowel movements, diarrhea

Autoimmune response: Graves' Disease

  • Most likely to cause Hyperthyroidism
  • Enlarged thyroid, goiter
  • Deficiency (or excess) in iodine
  • TSI antibodies, mainly IgG (immunoglobulins), cause thyroid gland to produce excess thyroid hormone which results in a low TSH (12)

Hypothyroidism, underactive thyroid producing low levels of thyroid hormone (T4, T3)

  • Slow metabolic rate
  • Slow heart rate
  • Lowered blood pressure
  • Sensitivity to cold
  • Irregular menstrual cycles
  • Weight gain
  • Constipation

Autoimmune response: Hashimoto's Thyroiditis

  • Selenium deficiency
  • Iodine deficiency or excess

How to Test Your Thyroid?

Having a thyroid panel done is usually the best way to evaluate the status of your thyroid.  The lab tests* should include the following (13):

  • TSH
  • Free T3
  • Free T4
  • TPOAb (Thyroid peroxidase antibody)
  • TgAb (Thyroglobulin antibody)
    • Measures antibodies to the protein thyroglobulin.  Positive results indicate antibodies found and may be linked to any of the following: Grave's disease, over/or underactive thyroid, Hashimoto's thyroiditis, thyroid cancer, subacute thyroiditis, type 1 diabetes, or systemic lupus erythematosus.)
  • TSI (Thyroid stimulating Immunoglobulin)
    • Measures antibodies of TSI in the blood as an indicator of Grave's disease.  TSI mimics TSH (thyroid stimulating hormone) signaling for the production of T3 and T4 and as a result can cause hyperthyroidism.

*Working with a physician will help you understand the test results for the full panel that is completed.  Thyroid medication (e.g., armour thyroid or nature-throid) is usually part of the treatment protocol for improving thyroid.

The Iodine-Selenium Connection

Iodine is a necessary nutrient for both thyroid function and immune function.  Iodine plays a key role in the production of thyroid hormones which are critical for metabolic functions.   Thyroid hormones are made up of Iodine where T4 has 4 iodines attached to a peptide and in order to make T3, an iodine atom has to be removed via the role of selenium-containing deiodinase enzyme.  The primary role of T3 is to increase metabolic rate.  Cells respond to the increased metabolism by working harder and using more energy.  However, the body cannot produce iodine on its own and needs to consume it daily or iodine will be removed from reserves throughout the body.  Calcitonin, produced by the thyroid gland, plays a key role in balancing calcium levels by reducing blood calcium in the body.  If the thyroid does not have enough iodine, it can not produce calcitonin.  Insufficient intake of iodine can cause TSH levels to elevate and can lead to a goiter (enlarged thyroid gland).  In order to make T3, the body needs both selenium and iodine minerals.  Both are important for immune function: selenium for organs that heavily use antioxidants (thyroid, gut, and immune cells) and iodine for neutrophils (white blood cells) to kill bacteria and fungus growth.  A deficiency in either or both may lead to an autoimmune disease resulting in damage to the thyroid gland resulting in either hyper/hypo-thyroidism.

Since immune cells obtain iodine by stripping it from thyroid hormone using selenium-containing deiodinase enzymes, a deficiency of either selenium or iodine will impair immune function
— "Perfect Health Diet", Paul Jaminet, PH.D and Shou-Ching Jaminet, PH.D

A word of caution: Hashimoto’s or Graves’ disease may be made worse with iodine supplementation.*  It’s best to have a TPO/TSI antibody count tested to determine if you have an autoimmune condition.  It is also important to understand the role of iodine and thyroid health with selenium.  Selenium protects the thyroid from damage caused by iodine and many individuals suffering with Hashimoto’s have had success with iodine supplementation when selenium supplementation was also provided.  It is best to maintain optimal (neither deficient nor excess) selenium intake.

    Best Food Sources of Iodine

     Photo by chengyuz

    Excellent sources (130mcg to 750mcg)

    • Sea vegetables (kombu/kelp, wakame, arame, laver, dulse)
    • Cod
    • Scallops

    Great sources (45mcg to 75mcg)

    • Yogurt (Grass-fed)
    • Shrimp
    • Cranberries
    • Potatoes (organic is very important)

    Good sources (10mcg to 35mcg)

    • Sardines
    • Salmon
    • Cow's milk (grass-fed)
    • Eggs
    • Tuna
    • Navy beans
    • Raw cheese (grass-fed)
    • Strawberries

    Poor Sources (Not Recommended)

    Iodized salt contains sodium and chloride content.
    Do to the standard American diet (SAD) containing more sodium than needed from a majority of processed and refined foods where iodized salt is no longer used, getting iodine from salt would require an additional 1,500mg of sodium to the already high salt diet.  It is best to get iodine from natural sources such as seafood to decrease sodium intake for iodine supplementation. 
    It used to be that iodized salt was used to supplement iodine in most food sources, but over time the use of iodized salt diminished and now is rarely (if ever) seen in a majority of processed foods that occupy much of the SAD diet.

    Supplements for Iodine (Inorganic Form)

    • Potassium Iodide- liquid
    • Potassium Iodide-tablets

    Optimal Iodine Levels

    High or low intake of iodine may cause injury to the thyroid gland resulting in hypothyroidism.  Provided that selenium daily intake is between 200-400mcg, the thyroid gland should remain healthy on a wide range of iodine intake.  Iodine intake should gradually increase to decrease the incidence of thyroid damage and allow the thyroid to adapt gradually, as the thyroid may not be able to adapt to high iodine doses.  Regular consumption of seafood and supplementation of 225mcg of potassium iodide on days where seafood is not consumed should maintain daily iodine averages.  Unfortunately, kelp may also contain high concentrations of toxins such as naturally occurring bromine compounds, arsenic, mercury, and potentially radioactive contaminants.  Good sources of iodine from sea vegetables include wakame, dulse, nori and laver.  It is important to make sure that selenium intake is above 200mcg per day as this should support iodine functions and prevent negative effects from high intake (up to 50mg) of iodine.*
    *Always consult a physician before starting any therapeutic doses of iodine as problems can arise if not implemented properly and adjusted appropriate to condition.

    Factors that May Interfere with Iodine Levels

    • Bromine and Bromides (found in plastics, soft drinks, pesticides, and processed foods)
    • Chlorine (bleaching agents used in food and chlorine added to water supply)
    • Fluoride (toothpaste, dental visits)
    • Soy (commonly consumed in its GMO form and often containing herbicides and pesticides that are toxic to the thyroid gland as well as other organ systems)
      • Soy contains goitrogens that can interfere with iodine uptake; contains phytic acid which may also inhibit the absorption of iodine and nutrient compounds that support thyroid health; may contribute to food allergies and digestive intolerances; contains estrogenic properties that affect hormones and mood. 
        Note: organic fermented soy in the form of natto, miso, and tempeh may have health benefits that oppose many of the negative factors commonly seen with non-fermented forms of soy.  Organic fermented soy will not contain GMO and will break down goitrogens but will still contain phytoestrogens that affect hormones.
    • Phytic Acid (Phytate)
      • Lentils, grains, beans, nuts, and seeds contain phytic acid (phosphate-rich inositol) which binds to important minerals such as calcium, iron, zinc, and magnesium.  Phytic acid also inhibits enzymes needed for digestion (breakdown of starches and proteins) and can make digestive problems like "leaky gut" worse.  Consumption of foods containing high amounts of phytic acid (without breaking down phytic acid content) may result in iron and zinc deficiencies and may interfere with absorption of calcium and magnesium. 
      • Preparation: phytic acid content can be greatly reduced by taking some extra steps to ensure the plant defense mechanism is deactivated.  Soaking, sprouting, dehydrating, boiling, and roasting are some great ways to reduce the content of phytic acid.  For more information on how to deactivate phytic acid in your plant foods, click here.

    How to Test for Iodine Deficiency

    • One-sample urine test (general test, not as accurate)
    • Iodine patch test (testing for mild to severe iodine deficiency)
    • 24-hour iodine loading test (ingestion of iodine/iodide followed by urine sample; total excreted should exceed 90% iodine/iodide excreted) (14)
    • Liquid SSKI test (super-saturated liquid of potassium iodine)

    Best Food Sources of Selenium

    Animal sources provide the primary form of selenium (as selenocysteine) for synthesis of selenoproteins.  Selenium functions closely in the body with proteins as selenoproteins (a protein that includes selenocysteine).  Selenoproteins are then used throughout the body as an antioxidant, thyroid hormone regulator, and essential regulator of redox homeostasis. (15)

    • Fish (tuna, sardines, salmon, cod)
    • Shellfish (oysters, clams, scallops)
    • Shrimp (may contain toxins, like mercury)
    • Eggs
    • Meat (Turkey, Chicken, Lamb, Beef)
    • Liver and Kidney (Grass-fed, organic)

    Plant sources deliver selenium primarily as selenomethionine which enhances conversion of selenoenzymes to glutathione peroxidase (antioxidant to H202).  Nearly all plant foods contain at least some selenium, though some plants contain more than others.   Methionine has been shown to increase the activity of selenomethionine to selenoproteins with vitamin B6 as a supporter in the conversion of the glutathione peroxidase.

    Excellent Sources (10mcg - 24mcg/serving)

    • Mushrooms (shiitake, cremini)
    • Asparagus
    • Barley (contains gluten, may interfere with nutrient absorption)
    • Soy (estrogenic properties, may interfere with thyroid function)
    • Brown rice*
    • Sunflower seeds*
    • Sesame seeds*

    Good sources (1mcg - 5mcg/serving)

    • Flaxseeds
    • Cabbage
    • Spinach
    • Garlic
    • Broccoli
    • Swiss Chard
    • Kale
    • Nuts*
      *Additional preparation is required to reduce phytic acid content

    Selenium Supporters

    In several studies, methionine (sulfur containing amino acid) in combination with selenomethionine has increased protein synthesis, peroxidase activity, and organ tissue storage of selenium.(16) Food sources that are considered good sources of methionine include: nuts, seeds, animal meats, fruits, cheese, fish, and legumes.  Similar foods that provide adequate intake of selenomethionine also contain significant amounts of methionine which suggest that these components are natural counterparts of each other. 

    Vitamin B6
    Vitamin B6 aids in the metabolism of selenomethionine which is important in activating methionine to support conversion of selenomethionine to selenocysteine and enhance the anti-carcinogenic enzyme properties of glutathione peroxidase. (17)

    Zinc works with selenium to convert T4 to T3.  However, some of the same foods that contribute large amounts of selenium may cause interference of zinc absorption.  High fiber foods that contain phytates interfere with the absorption of zinc.  However, when phytic acid is reduced in these high fiber foods zinc absorption drastically improves.(18)  Processes that decrease phytic acid in high fiber foods would include leavening breads, soaking legumes, germinating, and cooking foods. 

    Zinc and Other Nutrients
    Calcium and phosphorus do not negatively affect zinc absorption unless combined with meals containing phytates. (19)
    Iron does not appear to interact with zinc absorption unless taken at very high dosages while fasting. (20)
    High doses of zinc may interfere with copper absorption and is advised that when supplementing with zinc, copper should also be supplemented.

    Optimal Selenium Levels

    In most vegetables selenium content is low except in grains, nuts and seeds with the main source of selenium in the selenomethionine form.  Selenium intake from plant sources are necessary because they provide dietary macro/micro nutrients necessary for metabolic processes.  It is also important obtain selenium in the protein form (as selenoprotein) for cellular processes that promote antioxidant and selenium transport functions. (21

    How to Test for Selenium Deficiency

    • Blood test through a lab will provide the best results for determining a deficiency in Selenium.

    Books for Guidance on Thyroid Treatment

    (provided links: affiliate BF4L store)

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