What is the thyroid gland?
The thyroid is one of the largest endocrine glands in the body. This small butterfly-shaped organ sits in front of the windpipe (trachea) in the neck and weighs 20 to 30 g. (27) The thyroid secretes thyroid hormones, essential for regulating metabolism and body temperature, influencing growth and development, and controlling calcium levels in the blood. (27) The thyroid gland is responsible for several functions, including:- Controlling how well you burn calories
- Producing heat and energy in the body
- Regulating the speed at which food moves through your digestive tract
- Regulating your heartbeat and how much blood goes into circulation (4)(15)(36)
Thyroid hormone function
It is important to understand the function of thyroid hormones. Normal thyroid function is maintained through the hypothalamic-pituitary-thyroid (HPAT) axis, which is a feedback loop that involves the hypothalamus, anterior lobe of the pituitary gland, and adrenal glands. When thyroid hormone levels are low, the hypothalamus releases thyroid-releasing hormone (TRH) to stimulate the pituitary to release thyroid-stimulating hormone (TSH). The thyroid responds to TSH by producing and secreting more T3 (triiodothyronine) and T4 (thyroxine) hormones into blood circulation. When T4 arrives at the targeted body tissue, an iodine derivative (5-iodinase) converts T4 into its more bioactive form T3. This regulates metabolism and body temperature, generates and absorbs glucose for energy, and increases blood output from the heart. (4)(7)(18)(36)
The HPAT axis is a feedback loop used to maintain healthy thyroid hormone levels in the body. (35)
Common thyroid disorders: hypothyroidism vs. hyperthyroidism
Thyroid disorders affect up to 5% of the population, with hypothyroidism and hyperthyroidism being the most common. (4)(7)(13) If left untreated, they can increase the risk of adverse cardiac events and high blood pressure, elevated cholesterol, brittle bones, muscle weakness, peripheral neuropathy, cognitive impairment, and infertility. (10)(12)(22)(32) Speak to your integrative healthcare provider about your thyroid health if you suspect an issue with your thyroid. Assessment may include taking your medical history, a physical exam, and thyroid function testing. Treatment goals include returning thyroid levels to normal levels and preventing long-term complications. (3)(12)(22)(37)(38)What is hyperthyroidism?
Hyperthyroidism, a condition that affects approximately 1.3% of the population, occurs when the thyroid gland produces and secretes too much thyroid hormone. (13)(17) Common causes of hyperthyroidism include:- Excessive iodine consumption
- Grave’s disease: an autoimmune condition characterized by the destruction of thyroid tissue
- Goiter: enlargement of the thyroid gland causing overproduction of thyroid hormones
- Overmedicating with synthetic thyroid hormone
- Pituitary abnormalities: noncancerous (adenoma) tumor causing too much TSH
- Thyroid nodules: cysts or nodules causing overproduction of thyroid hormone
- Thyroiditis: inflammation of the thyroid gland causing too much then too little thyroid hormone (4)(10)(13)(22)(36)
Signs and symptoms of hyperthyroidism
An overactive thyroid occurs when the thyroid gland produces too much thyroid hormone. In the early stages, symptoms may be gradual or develop suddenly. Signs and symptoms of hyperthyroidism include restlessness and difficulty sleeping, weight loss, eye issues, and hot body temperature. Common symptoms in women and men include:- Difficulty putting on weight, despite increased appetite
- Dry and red eyes, the appearance of bulging eyes
- Enlarged thyroid gland (goiter)
- Excessive sweating
- Fast heartbeat (palpitations)
- Frequent bowel movements or diarrhea
- Heat sensitivity
- High (systolic) blood pressure
- Mood swings, irritability, and anxiety
- Nervous energy
- Restlessness and difficulty sleeping
- Shaky, tremors, and trembling
- Weight loss (3)(10)(22)(32)(37)(43)
Hypothyroidism and hyperthyroidism are the two most common forms of thyroid dysfunction.
What is hypothyroidism?
Hypothyroidism, affecting 4.6% of the population, results when the thyroid gland does not produce and secrete enough thyroid hormone. (13)(17) Common causes of hypothyroidism include:- Certain medications: some medications may interfere with thyroid hormone production, including amiodarone, interferon alpha, lithium, and interleukin-2 (38)
- Congenital hypothyroidism: babies born with an underdeveloped or under-functioning thyroid
- Hashimoto’s thyroiditis: an autoimmune condition characterized by chronic inflammation and destruction of the thyroid tissue
- Iodine deficiency: results from insufficient iodine intake
- Pituitary abnormalities: from noncancerous (adenoma) tumor causing too much TSH
- Radiation treatment: can destroy thyroid cells resulting in too little thyroid hormone
- Secondary hypothyroidism: the pituitary gland fails to produce enough TSH
- Surgical removal: part or all of the thyroid gland removed, resulting in too little thyroid hormone
- Thyroiditis: inflammation of the thyroid gland causing too much then too little thyroid hormone (4)(10)(12)(13)(36)(38)
Signs and symptoms of hypothyroidism
An underactive thyroid occurs when the thyroid gland does not produce enough thyroid hormone. In the early stages, symptoms may be mild with a gradual onset. Signs and symptoms of hypothyroidism are similar in both women and men and include fatigue, weight gain, hair loss, and chilliness. Common symptoms in women and men, include:- Brittle, thinning hair, and hair loss
- Constipation
- Depression
- Dry skin
- Enlarged thyroid gland (goiter)
- Erectile dysfunction
- Eyebrow thinning (outer third)
- Hoarseness and feelings of fullness in the throat
- Hormonal issues
- Infertility
- Irregular or heavy periods
- Low libido
- Memory problems
- Muscle aches and weakness
- Sensitivity to cold
- Slow heart rate
- Tiredness or fatigue
- Weight gain (3)(4)(6)(10)(12)(32)(38)(43)
Subclinical hypothyroidism
Subclinical (borderline) hypothyroidism affects up to 10% of the adult population. (5) It is more common in women and usually presents with no symptoms. Clinically, it is observed with an elevated TSH and normal free T4 levels. If left untreated, 2 to 5% of subclinical hypothyroidism cases can progress to symptomatic hypothyroidism. (3)(20)(31)Top foods and nutrients for a healthy thyroid
Support thyroid health by eliminating specific foods, focusing on diet quality and consuming whole foods, and using targeted supplementation when advised by your integrative healthcare practitioner.Incorporate high-quality thyroid-friendly foods
Support your thyroid by consuming various whole, unprocessed foods containing thyroid-friendly nutrients, including:- Fruits and vegetables (19)
- Gluten-free grains and pseudograins (e.g., oats, brown rice, quinoa) (22)(40)
- Healthy fats (e.g., plant oils, extra virgin olive oil) (19)(30)
- Lean meats, fish, and eggs (19)(39)(40)(41)
- Nuts and seeds (excluding peanuts) (19)(40)(41)
Thyroid-friendly foods include lean meats, fish and seafood, eggs, a variety of fruits and vegetables, legumes, nuts and seeds, and healthy fats.
Focus on consuming foods rich in zinc, selenium, and iodine
Specific minerals are needed to maintain thyroid gland function and essential for overall thyroid health. (1)(21)(28)(42)(45)(46) Zinc, selenium, and iodine can be obtained in the diet by consuming thyroid-friendly foods, including:- Zinc-rich foods: oysters, beef, crab, lobster, baked beans, pumpkin seeds, cashews, almonds, kidney beans, eggs, green peas, dark chocolate (41)
- Selenium-rich foods: brazil nuts, tuna, halibut, sardines, beef, turkey, chicken,brown rice, eggs, baked beans, lentils, cashews, green peas (40)
- Iodine-rich foods: seaweed, dulse, kelp, cod, yogurt, oysters, eggs, liver, cheddar cheese, shrimp, iodine enriched breads and salt (39)
Limit or eliminate goitrogenic foods
A hypothyroid diet should limit or eliminate raw foods that contain goitrogens, which interfere with the uptake of iodine and suppress thyroid function. Cooking these foods may inactivate goitrogenic compounds. Sufficient iodine levels in the body have been shown to have a protective thyroid effect. (2)(8)(9)(23)(26) Examples of goitrogenic foods that should be limited or avoided by individuals with hypothyroidism include:- Fruit: strawberries, peaches, pears (8)
- Grains: millet, gluten-contains grains (e.g., wheat, barley, rye) (2)(23)
- Legumes: soybeans, soy-based foods, peanuts (2)(8)(9)
- Oils: canola, rapeseed (8)
- Vegetables (mainly from the Brassica family): broccoli, brussels sprouts, cabbage, cauliflower, mustard greens, radishes, kale, spinach, sweet potato, and cassava (2)(8)(26)
Dietary supplements for a healthy thyroid
Optimal nutrients for thyroid health included specific minerals and amino acids to promote and maintain normal thyroid gland function. Selenium and iodine are essential for thyroid health. Speak with a healthcare professional to determine if supplementation is right for you.Zinc and selenium
Zinc and selenium deficiency may cause low thyroid and immune function. Supplemental zinc and selenium have been shown to promote thyroid function by contributing to:- Maintaining normal thyroid function
- Supporting TSH and thyroid hormone production
- Converting T4 to the active T3 form of thyroid hormone
- Exhibiting antioxidant activity to protect the thyroid from inflammation and free radical damage (1)(11)(21)(25)(28)(42)(45)
Iodine
Iodine deficiency increases the risk of goiter and hypothyroidism. Research has demonstrated that supplemental iodine supports thyroid hormone production. (16)(46)L-tyrosine
The amino acid L-tyrosine is used as a building block used to produce thyroid hormones. (33) With iodine, it is needed to make thyroglobulin (thyroid protein), a precursor to T3 and T4 thyroid hormones. (14)(29)(33) Supplementing with L-tyrosine may help to optimize thyroid hormone levels and thyroid function. (29)(44)The bottom line
The thyroid gland is a small but mighty organ, influencing the entire body. (4)(7)(13) Thyroid disorders affect up to 5% of the population, with hypothyroidism and hyperthyroidism being the most common forms of thyroid dysfunction. (7) Research has demonstrated that thyroid health may benefit from a thyroid-friendly diet and certain dietary supplements, including zinc, selenium, iodine, and L-tyrosine. (19)(21)(24)(29)(46) Healthy thyroid function helps support balanced energy levels, healthy weight management, improved stress resilience, stable body temperature, and better hair, skin, and nail health. (4)(15)(36) If you suspect you have a thyroid issue, speak to your healthcare practitioner about a thyroid assessment and to find out which supplements may be right for you.References
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