Thyroid Health - Naturopathic Approaches to Strengthening the Thyroid

The thyroid gland is an endocrine organ responsible for metabolism in the body, regulating functions such as energy use, body temperature and heart rate. The thyroid gland first produces and secretes the hormone thyroxine (T4), generally an inactive hormone, which is then converted to its active form, triiodothyronine (T3). Our pituitary gland secretes a hormone called thyroid stimulating hormone (TSH), which mediates the release of T4 from the thyroid gland through a negative feedback signal – when thyroid hormones are at good levels, this signals the pituitary gland to stop releasing TSH; when thyroid levels are low, the pituitary gland releases TSH in response. Hypothyroidism is a condition where the thyroid gland fails to produce adequate amounts of thyroid hormone. This could be due to a problem with the thyroid gland (primary), the pituitary gland (secondary), or the hypothalamus (tertiary), with primary making up 99% of hypothyroid cases.^[1] Hypothyroidism is present in all parts of the world and is the most common endocrine disorder seen by family physicians today.^[2]

It is typically characterized by symptoms including fatigue, dry, cool skin, constipation, brittle nails, hair loss and weight gain, but overall, symptoms can be very general and vague. If left untreated, hypothyroidism can lead to enlargement of the thyroid, hoarseness, water retention, thickening of skin, and can contribute to dyslipidemia, infertility, hypertension, and cognitive impairment.^[3] Primary hypothyroidism is generally diagnosed when blood concentrations of thyroid hormone, T4, is low, and TSH is high. There are a number of causes of hypothyroidism, the most common being thyroiditis, inflammation of the thyroid, caused by autoimmunity, viral infection, medications, birth defects, or pituitary gland defects.^[4] Women are more likely to develop hypothyroidism than men, with its incidence increasing with age, especially in those over 50 years of age.^[1] Hypothyroidism, however, is not an overnight process, with many people suffering from symptoms of hypothyroidism, but with blood concentrations of thyroid hormone coming back within the normal ranges.

Subclinical hypothyroidism (SCH) is a condition where some symptoms of hypothyroidism are present and TSH is read high, but T3 and T4 concentrations are within normal range. The prevalence of SCH in the general population is 4-8%^[5] and SCH can progress to overt hypothyroidism in 2-4% of the cases, annually.^[1] TSH is therefore the hormone used to diagnose and monitor treatment of subclinical hypothyroidism. Currently, most Canadian laboratories set TSH range between 0.35-5.0mU/L, but it is routine practice not to treat SCH until TSH measures about 10mU/L.^[6] It is general practice for most forward thinking clinicians to screen for SCH in patients within this range – lowering this upper limit as part of a screening process in those experiencing hypothyroid symptoms can guide clinicians to start supportive treatment in order to avoid progression to overt hypothyroidism.^[7,8] Not only do those with SCH experience symptoms of hypothyroidism, but has also been found to be at increased risk of other metabolic diseases such as cardiovascular disease and infertility/pregnancy loss.^[9,10]

Current treatment for hypothyroidism is treating with a synthetic version of T4 (thyroxin, or levothyroxin).^[2] This treatment is extremely effective in stabilizing the overt hormone imbalance found in hypothyroidism with minimal side effects, stabilizing TSH and T4 blood concentrations. However many clinicians report that patients, although feel better while on the therapy, still feel symptoms of hypothyroidism, despite the stabilization of hormone levels.

Naturopathic Approaches to Hypothyroid Symptoms

In clinical practice, it is imperative for naturopathic doctors to be able to catch symptoms of suboptimal thyroid function. From there, a treatment can be recommended that will stabilize and optimize thyroid function which does not involve hormone replacement. By optimizing thyroid function before it reaches hypothyroid state, we may be able to avoid the use of hormone replacement therapies, as well as improving day-to-day symptoms of suboptimal thyroid function. There are a number of naturopathic treatments that also work synergistically with T4 replacement, improving its function and to help relieve symptoms at the lowest dose possible.

Minerals

In order T4 to be optimally converted to T3, it must go through a series of chemical reactions. These chemical reactions utilize minerals to drive these reactions, primarily iodine and selenium.

Iodine is a mineral that is taken up by thyroid cells and serves as a backbone for thyroid hormone production. Iodine is incorporated in to thyroid proteins which go through a series of reactions to create T4 and T3. Therefore thyroid hormone synthesis cannot happen if there is no iodine to utilize. Iodine deficiency has been found to be a major cause of hypothyroidism and subclinical hypothyroidism and has been found to be climbing rapidly in developing countries.^[11,12] A recent study had found that prophylactic iodine supplementation in children with subclinical hypothyroidism improved overall metabolic health.^[13] Another study found that administration of iodine in the form of powdered kelp restored thyroid function and urinary iodine concentrations.^[11] Iodine is not made by the body so it is imperative that we take in foods that are rich in iodine in order to achieve optimal iodine status. The recommended daily intake of iodine is 150mcg daily in healthy adults. Foods that are rich in iodine include seafood (seaweeds like kelp and dulce), and fortified foods such as salt, dairy and bread, though these may not be the healthiest choices.^[13] If diet is not rich in these foods, then supplementation for those experience hypothyroid symptom is recommended. However it is important to consult with a healthcare practitioner who is educated in iodine dosing, as excessive intake has been found to exacerbate symptoms of hyperthyroidism.

Selenium is a mineral that is greatly utilized by the thyroid gland. Selenium is used by thyroid enzymes involved in the conversion of T4 to T3, mainly glutathione peroxidase, thioredoxin and all three iodothyronine de-iodinases. Selenium is also an antioxidant which protects the thyroid from damage by free radicals such as hydrogen peroxide, which are produced during the conversion of T4 to T3. Selenium deficiency can lead to poor functioning of the thyroid as the lack of selenium will slow down the function of these enzymes; this can eventually lead to chronic issues of the thyroid, such as inflammation and eventually the production of autoimmune antibodies. Selenium deficiency has also been linked to worsening iodine deficiency.^[14] A recent study found that adults with SCH responded favourably to selenium supplementation, with TSH decreasing by 31% compared to subjects not receiving selenium supplementation.^[15] Selenium supplementation also seems to work more favourably in those with hypothyroidism due to autoimmunity.^{[15, 16]} Rich sources of selenium include seafood’s such as fish, scallops and shrimp, as well as mushrooms, asparagus, mustard seeds and meat products, particularly turkey, lamb, chicken and beef. The current recommended daily intake of selenium is 55mcg/day for adults, with toxic doses being difficult to ingest daily.^[17]

Studies have found supplementation of iodine and selenium can optimize thyroid function. A study performed in 2000 found that supplementation of iodine in children with thyroid goiters and selenium deficiency, decreased the size of the goiter and optimized levels of TSH after 50 weeks of treatment. This study also found that the more depleted the children were in selenium, the less responsive they were to iodine supplementation.^[18] This shows that concomitant supplementation with selenium may improve and optimize iodine supplementation.

Exercise and Herbs

Exercise is important for maintaining good health in every individual. In those with hypothyroidism or SCH, exercise becomes even more important in order to counteract the effects of slower metabolism in those affected – this can help prevent and improve metabolic diseases associated with hypothyroidism and SCH such as obesity and cardiovascular disease.^[19] It is recommended that those with hypothyroidism or SCH participate in invigorating, heart rate-accelerating activities in order to maintain optimal metabolic rate, especially in those who are dieting.^[20]

Fucus vesiculosis (Bladderwrack) is a seaweed found on the coasts of the Atlantic and Pacific oceans. Though it has not been extensively researched on its direct effect on the thyroid, it has been traditionally used to treat goiter due to its high iodine content. The British Herbal Pharmacopoeia advocates for the use of Fucus vesiculosis for thyroid condition for its ability to stimulate T4 production and improve basal metabolic rate, due to its high, bioavailable iodine content.^[20]

Withania somnifera (Ashwagandha) is a flowering plant belonging to the Solanaceae family, mainly found in Africa and the Middle East and is a staple herb in Ayruvedic medicine. It has been traditionally used as an adaptogen and tonic, improving muscular energy, recovery from illness, and promoting the growth of children.^[20] The effect of Withania on the thyroid has been represented in animal studies, where the root extract has been found to increase serum concentrations of T4 in female mice after 20 days.^[21]

Discussion

Hypothyroidism is a condition that is prevalent in many parts of the world and can lead to generalized symptoms that many people can feel on a daily basis. Overt hypothyroidism can be detected through routine blood tests and can is treated by replenishing T4 through a synthetic derivative. However it is important to understand that subclinical hypothyroidism is also a prevalent condition and if left untreated can lead to overt hypothyroidism and can also lead to metabolic and hormonal conditions such as cardiovascular disease and infertility. Due to the health impacts of SCH, it is important to seek out a medical professional who practices well-researched screening protocols for thyroid disorders, especially if symptoms are present, despite normal blood levels of thyroid hormones. If SCH is diagnosed early enough, they could avoid progression to overt hypothyroidism through treatments which optimize thyroid function. Naturopathic treatments such as mineral supplementation, medicinal herbs, as well as exercise, can help one experience relief of hypothyroid symptoms, and restore optimal functioning of the thyroid gland.