What is the best thyroid support supplement for an underactive thyroid?

There are a whole range of thyroid support supplements for you to consider if you have an underactive thyroid. Which ones will optimise your thyroid function will depend to some extent on whether you have Hypothyroidism (an underactive thyroid) or Hashimoto’s Thyroiditis (an auto immune thyroid condition) and also on your diet but here are some key recommendations based on my clinical experience in practise.

Zinc important for thyroid hormone production and conversion and 25mg dosage to help optimum zinc delivery to thyroid gland.

Selenium important mineral for thyroid function because it activates enzyme responsible for conversion of T4 to T3 the active thyroid hormone. Selenium supplementation shown to reduce inflammation with autoimmune thyroiditis. If you are on a low calorie diet this mineral together with Zinc is key in preventing decline of T3. Dosage of no more than 400mcg daily is recommended.

Tyrosine precursor thyroid hormone and low levels make it difficult for thyroid to work properly 85-170mg daily.

Guggul is an Ayurvedic thyroid stimulating agent which has the ability to take up enzymes needed for thyroid conversion and prevent sluggish thyroid metabolism.

Omega 3 and Omega 6 essential fatty acids critical to thyroid function because they increase energy levels in cells, required for integrity of structure of every membrane of every cell and improve body’s ability to detect and respond to thyroid hormone effectively

Iodine more controversial as whilst it is a cofactor for thyroid function but whilst may tolerate small amount in a multi, too much can aggravate thyroid symptoms so get practitioner to test for iodine deficiency so this may be one where eating sea vegetables and other iodine rich foods may be seaweed/sushi or shellfish may be preferable to supplementation.

Ashwagandha an adaptogenic herb  may improve thyroid function by helping to increase T4 levels of thyroid hormone. T4 is the substrate for T3 and T3 thyroid hormone sets your metabolism and energy levels.

Thyroid Glandulars would be something to consider alongside your thyroid medication (levothyroxine) if you have an autoimmune thyroid condition or have permanent thyroid damage from radioactive iodine but only after a consultation with an Functional Medicine Practitioner. They contain animal thyroid tissue (usually in form of Bovine) and support the thyroid at a glandular and tissue level.

Important note – if you are taking Prescription medication (usually Levothyroxine) it is important to consult with your GP or a Functional Medicine Practitioner before taking new supplements.

For more information on thyroid support see my previous article on “How to boost Thyroid Function” published May 2020.

Book a FREE discovery call

If you suspect that you may have an under active thyroid and would like help in diagnosing and improving your situation, don’t hesitate to book in for a FREE discovery call using the form below.

Please enable JavaScript in your browser to complete this form.Name *

First

Last

Email *

Telephone number *

How can I help? *

Newsletter

• Please sign me up to your email newsletter

Privacy Policy *

• I have read and agree to your privacy policy

Email

Best Supplements For Hypothyroidism and When To Take Them

In this article:

• The nine best supplements to support thyroid health

• When is the best time to take your supplements?

• A note from Paloma Health

‍

More and more people are turning towards vitamins, minerals, herbs, and other nutraceuticals to aid in the management of chronic medical conditions including thyroid disease. In fact, by 2024 the market for dietary supplements may reach close to $280 billion, up from $37 billion in 2015! 

In this article, we cover nine supplements that can help support thyroid health. 

‍

The nine best supplements to support thyroid health

Ashwagandha

Ashwagandha is known for its adaptogenic properties, meaning it may improve your body’s response to stress. Besides stress management, ashwagandha may be beneficial in those with hypothyroidism by:

• Enhancing sleep 
• Improving memory and attention
• Increasing thyroid hormone levels
• Lowering blood pressure
• Stimulating immune system activity

‍

The long-term effects of taking ashwagandha are unknown. Those that are pregnant or breastfeeding should not take it. Ashwagandha can interact with medications including ones used for:

• Diabetes
• High blood pressure
• Hypothyroidism
• Immunosuppression
• Sedative and sleep  

Iron

Iron is mainly known for its role in transporting oxygen to your muscles. But, it also helps convert thyroxine (T4) to triiodothyronine (T3), the active form of thyroid hormone, and maintains thyroid stimulating hormone (TSH) levels. Iron-deficiency anemia is relatively common in those with hypothyroidism with some studies reporting a prevalence of over 40%.

Taking your iron supplements with vitamin C increases iron absorption. But, iron supplements can interfere with levothyroxine absorption, as well as the effectiveness of several other medications. Avoid taking your iron supplement with or within 2-3 hours of:

• Antacids
• Antibiotics like ciprofloxacin or penicillin
• Thyroid medication, like levothyroxine
• Medications used for Parkinson’s disease and seizures

Magnesium

Magnesium is a cofactor for many enzyme-related processes in our body including energy production, blood sugar control, and muscle and nerve function. The benefits of taking magnesium in those with hypothyroidism include:

• Improvement in sleep
• Lowering blood pressure
• Optimization of bone health
• Reduction in headaches including migraines

Beware of magnesium-containing antacids and laxatives as taking too much magnesium can be harmful. Magnesium decreases the absorption of levothyroxine and bisphosphonates, a medication used to treat osteoporosis, and certain antibiotics. Take these medications 2-3 hours before or 4 to 6 hours after magnesium-containing supplements. 

Myo-inositol

Myo-inositol is essential for our signaling hormones, including TSH. Signaling hormones tell our cells when to start or stop a certain action. A change in myo-inositol levels may alter thyroid hormone production, secretion, and storage.

When myo-inositol and selenomethionine, a form of selenium, are taken together, those with Hashimoto’s thyroiditis or an underactive thyroid may experience a:

• Decrease in TSH and thyroid autoantibodies
• Increase in thyroid hormone levels
• Improvement in thyroid nodular disease

Selenium

Your thyroid gland contains high amounts of selenium, as selenium is important for converting T4 to T3 and healthy thyroid levels. Selenium may also:

• Improve immune system function
• Provide antioxidant properties 
• Reduce thyroid antibodies in Hashimoto’s‍

Daily Thyroid Care

$34/month

The reinvented multivitamin that works smarter to help fill the gaps in your thyroid health journey

Learn More

Vegan and free of gluten, GMOs, dairy and iodine

‍ 

Turmeric

Turmeric is commonly found in the spice aisle and contains curcumin. Curcumin is responsible for the medicinal effects and the bright yellow color of turmeric. 

In traditional medicine, turmeric helps reduce inflammation and oxidative stress markers in those with an autoimmune disorder like Hashimoto’s. Turmeric may also create an intestinal barrier to help with a leaky gut. This is beneficial to those with Hashimoto’s as leaky gut is thought to be one of the underlying causes. 

Vitamin B

Vitamin B, also known as thiamine, is one of the eight B vitamins that your body needs to make energy for your cells. Thiamine may decrease hypothyroidism-associated fatigue. 

Benfotiamine, a type of thiamine made in a lab, may block specific food compounds called advanced glycation end products from causing inflammation and oxidative stress in your body. Because of this, those with Hashimoto’s may benefit from benfotiamine as it targets two of the underlying causes. 

Vitamin B-12

Your body needs vitamin B-12 for forming red blood cells, proper cognitive function, and making new cells. Some refer to vitamin B12 as the energy vitamin as it helps improve:

• Energy levels
• Mood
• Cognitive function

‍

Nearly 40% of those with hypothyroidism have a B12 deficiency which may be caused by an autoimmune disorder called pernicious anemia. This is when your body can’t absorb vitamin B12 from the food you eat or from supplements. Because of this, your body doesn’t have enough red blood cells to carry oxygen to your muscles, leaving you feeling tired and fatigued. By managing your pernicious anemia with B12 injections, your energy levels and fatigue may improve. 

‍

Certain medications can interfere with vitamin B12 absorption including:

• Histamine 2 antagonist such as famotidine
• Metformin (Glucophage)
• Proton pump inhibitors like Prilosec or Nexium

Zinc

Zinc is a mineral that many people associate with helping to fight off colds. Besides helping our immune function, zinc also plays a role in producing thyroid hormones and healing leaky gut. 

Several prescription medications like antibiotics or diuretics can interact with zinc supplements. Thus, it is important to separate your zinc supplement from those medications. In general, take medications 2 hours before your zinc supplement or 4 to 6 hours after. 

‍

When is the best time to take your supplements?

It depends on what works best for you. Some find it easier to take supplements in the morning while others prefer the evening. The key is to be consistent in how and when you take them. 

Consider the following questions when trying to determine a schedule:

• Do any of your medications or foods interact with the supplements? If so, how much time do you need between them?
• How many times a day do you need to take each supplement? 
• Can you take all supplements and medications in one sitting (as some pills can be large)?
• Should they be taken with food or on an empty stomach?

Your pharmacist or thyroid doctor can help you determine a schedule to take your supplements. 

‍

A note from Paloma Health

Vitamins and minerals play a key role in our body’s function. But, taking multiple supplements in addition to your medications may increase your pill burden. Consider Paloma’s Daily Thyroid Care supplement. It is an iodine-free combination of nine essential nutrients your thyroid gland needs for optimal function.

Working with a Paloma Health dietician can help create a personalized supplement and nutritional plan to help lower antibodies and support optimal thyroid function.

Six Natural Ways to Control Hashimoto’s Disease｜ iHerb Blog

The information in this blog has not been verified by your country’s public health authority and is not intended as a diagnosis, treatment, or medical advice.
Read more

If you’re struggling with fatigue or unexpected weight gain, you’ve probably wondered if a thyroid problem could be the cause. In fact, these are far from all the symptoms that occur with hypothyroidism, indicating an underactive thyroid gland.

But the thyroid may not be the main cause of your symptoms. It is estimated that 90% of patients diagnosed with hypothyroidism actually have Hashimoto’s thyroiditis, also called chronic lymphocytic thyroiditis. In this autoimmune disease, the body mistakenly attacks its own tissues.

In Hashimoto’s thyroiditis, the immune system infiltrates and damages the thyroid gland, a small, butterfly-shaped gland in the front of the neck. Specifically, immune cells produce proteins called antibodies that trap and neutralize substances needed to make thyroid hormone. The resulting low thyroid hormone levels lead to the development of a wide range of possible symptoms.

Signs and symptoms of autoimmune thyroiditis (Hashimoto’s thyroiditis)

Symptoms may be mild and barely noticeable at first. But over time it becomes more and more obvious. In general, the disease involves a slow and progressive destruction of the thyroid gland. However, there may be intermittent periods during which symptoms change as the thyroid gland appears to regain function. These changes can even cause temporary overactivity of the thyroid gland.

• Fatigue and lethargy
• Unreasonable weight gain
• Puffy face
• Insomnia
• Forgetfulness
• Anxiety and depression
• Gi pertonia
• Periodic sweating, weight loss and irritability
• Sore throat
• Enlarged tongue
• Difficulty swallowing
• Swelling in the front of the neck
• Acne
• Rash
• Headache
• Bloating
• Constipation
• Dry, pale skin
• Brittle nails
• Hair loss
• Hypersensitivity to cold
• Joint pain and stiffness
• Muscle cramps
• Stiff and weak muscles
• High cholesterol
• Female infertility
• Excessive and prolonged menstrual bleeding

What causes the immune system to attack the thyroid gland?

The exact cause is unknown, but genetic factors seem to play a role in the development of autoimmune thyroiditis. The occurrence of this disease can also contribute to a combination of factors such as age, gender, autoimmune or endocrine disorders. Genes, of course, cannot be changed, but something can still be done to eliminate possible triggers of an autoimmune response. This is the key to proper treatment of autoimmune thyroiditis.

Six Ways to Manage Autoimmune Thyroiditis Naturally

Conventional thyroid medications can improve thyroid hormone levels and help relieve symptoms, but do not address the real problem of immune system dysfunction. If you can determine which factors are responsible for the autoimmune response, then you can naturally fight the disease by removing those triggers.

Here are six factors to consider if you want to reduce your autoimmune response with natural solutions.

1. Nutrient deficiencies

Many different nutrients are needed for normal thyroid and immune system function. When these substances are lacking in the body, the predisposition to the development of autoimmune diseases, such as autoimmune thyroiditis, may increase.

• Selenium is needed to convert T4 (inactive form of thyroid hormone) to T3 (active form). Without enough selenium, thyroid hormone remains inactive, which can lead to symptoms of autoimmune thyroiditis. In addition, studies show that when taking selenium in patients with autoimmune thyroidism, the level of antibodies to the thyroid gland decreases. The usual starting dose is 200 micrograms. But there is a narrow window between effective and toxic dosage. Therefore, it is wise to seek the help of a doctor to find the right dosage.
• Zinc: Low zinc compromises T3 production because zinc also interferes with the enzymatic conversion of T4 to T3. When zinc is deficient, the hypothalamus has difficulty measuring thyroid hormone levels. This impairs the body’s ability to properly signal the production of thyroid hormones when levels become low. It is recommended that you take no more than 30 mg of zinc per day, unless a higher dose is prescribed by your doctor.
• Vitamin D deficiency is associated with the presence of thyroid antibodies. All patients with autoimmune thyroiditis should have their 25-hydroxy vitamin D levels checked annually. Research suggests that levels of 60-80 ng/mL should be maintained for optimal thyroid and immune system function. When it comes to supplementation to increase vitamin D levels, it is better to choose vitamin D3 over D2. The starting dosage is usually in the range of 2,000 to 5,000 IU, with adjustment under the supervision of a physician after rechecking vitamin D levels three months later.
• Iron plays a key role in the production of thyroid hormones. It is also needed to convert T4 to T3. To determine if you are truly iron deficient and need an iron supplement, you will need to be tested for: ferritin levels, serum iron levels, as well as transferrin saturation and total iron binding capacity. Your healthcare provider can help you interpret the results and advise you on the correct iron dosage.

When choosing an iron supplement, please note that iron bis-glycinate is the form that is generally better absorbed and less firm than other iron tablets. If you are taking thyroid medication, do not take an iron supplement within two hours of taking your medication because the iron may interfere with the absorption of the medication.

You can also increase your iron content by eating foods such as red meat, poultry, beans, and dark green leafy vegetables. But keep in mind that iron from plant sources is absorbed worse than from animal sources. If you choose plant sources of iron, vitamin C can help improve iron absorption.

2. Reducing the intake of foods that cause inflammation

Reducing inflammation in the body is the goal of treating autoimmune thyroiditis. Therefore, it makes sense to exclude from your diet those foods that can cause inflammation. Different people develop food allergies to different foods. The following foods contribute most to inflammation:

• Gluten
• Sugar
• Saturated fat
• Artificial sweeteners or preservatives
• Certain components of dairy products (eg, lactose or A1 beta-casein protein)
• Soy, corn, sunflower, cottonseed, safflower, and mixed vegetable oils

Your health care provider may refer you for a blood test for food allergies. You can use this information to refuse products to which you are sensitive. You can find out what food you are allergic to on your own with the help of an allergen-free / provocative diet.

With this diet, one food category should be eliminated for three weeks. Then you need to add the product to the diet again for three days and evaluate your reaction. Monitor for any food allergy symptoms such as bloating, fatigue, headache, joint pain, loose stools, constipation, insomnia, or skin changes.

The following product categories can be checked:

• Gluten
• Corn
• Other gluten-free cereals
• Dairy products
• Soybeans
• Eggs
• Nuts
• Legumes
• Shellfish
• Solanaceae (common nightshade vegetables include peppers, potatoes, tomatoes, and eggplant ana)

There is a faster version of the allergen-free diet: eliminate all of the above from the diet product categories for three weeks. Then reintroduce each food category in turn every three days. If no symptoms occur when the food is reintroduced, then you can leave the product in your diet. If symptoms do occur, avoid this product again.

3. Improved bowel function

About 70-80% of the cells of the immune system are found in the gut. Therefore, by improving the functioning of the intestines, you strengthen the immune system.

Most patients with autoimmune thyroiditis have low gastric acidity. With low acidity, the intestines absorb nutrients worse. Bacteria and other microorganisms also survive more easily when they pass through the stomach in a less acidic environment. This allows them to gain a foothold in other parts of the body and cause infection.

Betaine HCl (hydrochloride) is a supplement that can help increase stomach acidity to optimal levels. It should be taken with the digestive enzyme pepsin after eating a high protein meal. This approach will help the body break down proteins more fully so that they also don’t act as an immune trigger.

In the intestinal microflora of many patients with autoimmune thyroiditis, dysbacteriosis is observed – an imbalance of beneficial and harmful bacteria. This usually happens because a deficiency of thyroid hormone slows down intestinal motility. By taking a quality probiotic, you can restore the good bacteria to a level where they keep the bad bacteria in check.

4. Consider the influence of infections

There are two possible explanations for how an infection can cause the immune system to attack the thyroid gland.

1. Bacteria or other microbes that are very similar to thyroid cells are subject to molecular mimicry. When the immune system produces antibodies to kill infectious microbes, the antibodies also attack similar thyroid cells.
2. The theory of how microbes enter thyroid cells can be described as the bystander effect. In the process of destroying microbes, the immune system also attacks the cells that contain them.

Infections most commonly associated with autoimmune thyroiditis include candida, mycoplasma, and Epstein-Barr virus. It is worth checking for the presence of infections in the body of any localization and how to treat them.

5. Adrenal Reduction

When you are under stress, your adrenal glands release cortisol, which signals a decrease in thyroid hormone production. Therefore, all treatment regimens for autoimmune thyroiditis should include stress management measures such as yoga, meditation, or breathing exercises.

Adaptogens are natural substances that can also help you manage stress appropriately. Adaptogen has the ability to stimulate a weakened immune system and mitigate an overactive reaction. Thus, an adaptogen helps the body adapt to stress in order to normalize the work of all systems and organs in any suitable way. Examples of adaptogens include reishi, eleutherococcus, lemongrass, and ashwagandha.

6. Avoid Toxins

There are many toxic chemicals in the environment that can harm your body in a variety of ways—causing inflammation, disrupting your hormones, and increasing your risk of developing an autoimmune response. Getting rid of all toxins is difficult. But there are a few things you can do to reduce their effect on your thyroid:

• avoid chemicals that destroy hormones. The Environmental Working Group (EWG) has compiled a list of chemicals that can negatively affect the human endocrine system. Avoid products that contain: lead, dioxin, atrazine, phthalates, perchlorate, fire retardants (polybrominated diphenyl ethers), arsenic, mercury, glycol ethers, perfluorinated chemicals (PFCs), organophosphate pesticides, bisphenol A (BPA or Bisphenol substitutes) A, such as BPF and BPS).
• Use clean personal care products. Many face and body beauty products contain harmful chemicals that can disrupt your endocrine (hormonal) system. Read the composition of the product and make a choice in favor of the most natural products. See the EWG’s list of chemicals to avoid.
• Purify the air you breathe, especially if you live in an industrial area. Consider installing a HEPA (high-efficiency particulate air) filter at home and at work.
• Try not to use plastic for food purposes, avoid contact of plastic with food or drinks. Plastics often contain BPA or BPA substitutes. Be careful with canned food too. Tin cans often contain BPA (although some companies use BPA-free cans and inform consumers about this).
• Purify the water. Install a fluoride drinking water filter and shower heads.
• Sweating! Sweating is one of the best mechanisms for removing toxins from the body. Exercising or even taking a sauna can help you sweat more. It never hurts to seek medical advice before changing your physical activity or taking a sauna, especially if you have heart problems.

Of course, some people may not be able to go off thyroid medication completely, but there are many natural ways to manage autoimmune thyroiditis that can help you feel better or even reduce your medication. If possible, find a medical practitioner who is experienced in treating thyroid disorders using both traditional remedies and conventional medicine. Always check with your doctor before changing medication dosages or introducing new supplements to your diet.

Use of selenium in medical practice | Shestakova T.P.

The article is devoted to the possibilities of using selenium in medical practice. Selenium is a trace element that is part of the enzymes that play an important role in the functioning of the thyroid gland, reproductive, immune systems and in carcinogenesis. Lack and excess of selenium are unfavorable for human health. The main organ that uses selenium is the thyroid gland. Selenium effectively reduces the level of antibodies to thyroperoxidase (TPO) in patients with autoimmune thyroiditis, improves the quality of life of patients with endocrine ophthalmopathy. Selenium is used in the clinical practice of endocrinologists for autoimmune thyroiditis and endocrine ophthalmopathy.

Introduction

Selenium is a trace element that was first described in 1817 by the Swedish chemist John Berzelius. It belongs to the 16th subgroup of the table of chemical elements of D.I. Mendeleev, where it stands between arsenic and bromine, and in its chemical properties it is similar to sulfur. Due to its ability to donate electrons, selenium is widely used in industry. In 1957, researchers Schwartz and Foltz found that selenium supplementation prevented the development of muscular dystrophy and liver cirrhosis in rats [1]. In subsequent years, it was revealed that selenium is an important element of the glutathione peroxidase enzyme [2], after which the study of the effect of selenium deficiency on human health and the possibility of using it in medical practice began. Its role in the functioning of the immune, endocrine and reproductive systems, metabolism, cellular homeostasis, and carcinogenesis was revealed.

Sources of selenium

The main source of selenium for a person is food, therefore, the content of selenium in the body is determined by the dietary preferences of a person. In turn, the content of selenium in food products depends on the place where the plants grow. The average content of selenium in the soil is 0.4 mg/kg [3]. But this number is not constant. It depends on the composition of the soil, including the proportion of organic matter in it, and the amount of precipitation falling in a given area [4]. In mountainous areas (Finland, Sweden, Scotland), soils are deficient in selenium, while clay soils and soils in regions with low rainfall usually contain an increased amount of this trace element. In most European countries, Egypt, Brazil, India, China, Saudi Arabia, Nepal, Burundi, New Guinea, separate regions with selenium deficiency have been identified. An excess of selenium is also found in certain regions of India, China, USA, Canada, Brazil, Venezuela, Japan. For comparison: in Europe, the average intake of selenium is 40 mcg / day, and in the USA – 93 µg/day for women and 134 µg/day for men [5].
Selenium is found not only in soil, but also in water. The average concentration of selenium in tap water is 10 µg/l, which is defined by the World Health Organization (WHO) as the minimum acceptable level of selenium in drinking water. In underwater waters, the concentration of selenium is somewhat higher, but it reaches the highest level in sea water, where it ranges from 4000 to 12000 μg of selenium per 1 l [6].
The content of selenium in plants varies considerably. It depends not only on the place of growth, but also on the ability of plants to capture selenium from the soil and accumulate it. In general, the selenium content is higher in vegetables than in fruits. The selenium content in cereals varies from 0.01 to 0.55 µg/g, in dairy products – from 0.001 to 0.17 µg/g [7]. According to a Belgian study, the main source of selenium for humans is meat products (31%), followed by fish (19%).%), bread and cereals (11%) [8].
In nature, selenium exists in the form of organic (selenomethionine and selenocysteine) and inorganic compounds (selenite and selenate). Considering that organic forms are better absorbed in the gastrointestinal tract, some experts consider them as the main ones for the prevention and treatment of diseases caused by selenium deficiency. Selenomethionine is found in plants, mainly in cereals, while selenocysteine ​​is found mainly in animal products. In food supplements, inorganic forms of selenium are more commonly used. Selenium is absorbed mainly in the small intestine (50-80%) and excreted through the kidneys (60%). Another 35% is excreted through the large intestine, 5% through sweat and saliva [9]. For reasons not yet understood, selenium levels are lower in smokers and decrease with age. In addition, selenium content is lower in individuals who consume large amounts of coffee and alcohol. Eating large amounts of rice and eggs is also associated with a reduced concentration of selenium in the body [10]. WHO recommends an intake of 50–55 micrograms of selenium per day [11].

Effects of selenium deficiency and excess on human health

Both the lack of selenium and its excess are dangerous for humans. Deficiency manifestations appear when selenium intake is less than 40 μg/day, and excess – when more than 400 μg/day is consumed [12]. Severe selenium deficiency leads to the development of Keshan disease, manifested by heart failure due to cardiomyopathy, atrophy, degeneration and necrosis of articular cartilage, and fever. But even a less pronounced lack of this microelement adversely affects the state of human health. Selenium acts as a catalytic site for several enzymes, such as glutathione peroxidase, thioreduxin reductase, and iodothyronine deiodinase, which protect the cell from oxidative stress, the action of free radicals, strengthen the immune system, are involved in the metabolism of thyroid hormones, etc. [7].
In some studies, selenium deficiency was associated with an increased risk of cardiovascular disease, which decreased when the deficiency was replenished. Selenium has an anticarcinogenic effect on the prostate, liver, pancreas, and large intestine. In addition, selenium is involved in embryo implantation, placental development, fertility enhancement by increasing sperm motility, testosterone and sperm synthesis [6].
With the consumption of more than 400 micrograms of selenium per day, the so-called selenite develops. This rare situation has been described in population studies with chronic selenium intoxication in regions with high natural content [13]. Symptoms of selenitis are nausea, vomiting, abdominal pain, diarrhea, hair loss, brittle nails, peripheral neuropathy, and a characteristic garlic odor in sweat and exhaled air. Cases of the development of selenite are described in case of an overdose of food additives with an increased content of it [14].

The role of selenium in the functioning of the thyroid gland

Selenium plays a special role in the functioning of the thyroid gland. This organ contains the largest amount of selenium per 1 g of tissue in the form of selenoproteins. The participation of selenium in the synthesis of thyroid hormones was first suspected after studies conducted in Zaire, where not only severe iodine deficiency was revealed, but also severe selenium deficiency. At the same time, the population had severe myxedematous cretinism and a pronounced intellectual deficit. After that, many studies have been conducted on the role of selenium in the functioning of the thyroid gland. As a result, it was shown that selenium affects the synthesis of thyroid hormones indirectly via selenoproteins [15] (Table 1). Thyroid status is mainly affected by selenium-containing deiodinases, which convert the inactive form of thyroid hormones (T ₄ ) into active (T ₃ ) by removing one iodine atom from the outer ring. In addition, they are able to convert T ₄ into an inactive form of the hormone – reverse T ₃ , splitting off one iodine atom from the inner nucleus.

But this is not limited to the role of selenium in the functioning of the thyroid gland. So, selenoprotein – glutathione peroxidase protects the thyroid gland from oxidative stress. The fact is that in the process of synthesis of thyroid hormones in thyrocytes, hydrogen peroxide (H ₂ O ₂ ), which is a powerful oxidant. Glutathione peroxidase has the ability to inactivate hydrogen peroxide and free radicals and thereby limit their damaging effects on thyroid tissue. It has been proven that when exposed to glutathione peroxidase, the concentration of prostaglandins and leukotrienes decreases, which indicates a decrease in inflammation [16].
With a deficiency of selenium, a lack of deiodinases of various types is formed, the formation of T9 decreases0224 3 , leading to stimulation of the hypothalamic-pituitary axis through a negative feedback system and an increase in the synthesis of thyroid-stimulating hormone (TSH). TSH stimulates the production of thyroid hormones and increases the activity of deiodinases, restoring the level of thyroid hormones. But at the same time, it stimulates the formation of hydrogen peroxide, for the inactivation of which, again, selenoprotein, glutathione peroxidase, is required, the activity of which is reduced under conditions of selenium deficiency. Hydrogen peroxide accumulates in the thyroid gland, which leads to damage to thyrocytes and the development of fibrosis [17, 18]. An increased formation of hydrogen peroxide in the thyrocyte is observed in all cases of excessive stimulation of the thyroid gland by TSH, for example, in patients with autoimmune thyroiditis and subclinical hypothyroidism. As a result, damage to thyrocytes, progression of hypothyroidism and development of fibrosis are observed. In such a situation, selenoproteins, having antioxidant activity, can prevent or at least slow down the destruction of thyrocytes and reduce their functional activity [15].
Thioreduxin reductase, like glutathione peroxidase, has antioxidant activity, but the role of this enzyme in the functioning of the thyroid gland is less studied.
Selenoprotein P is the main source of selenium in plasma, it performs the transport function and distribution function of the microelement in the body [19]. It is synthesized in the liver and is responsible for retaining selenium in the body and distributing it between organs. The main organs into which selenium enters from the blood are the liver, thyroid gland, and brain. However, the thyroid gland and the brain have the ability to retain and accumulate selenium even in conditions of selenoprotein P deficiency [20].

Place of selenium in the treatment and prevention of thyroid diseases

Autoimmune thyroiditis

Studies have shown that selenium deficiency plays an important role in damage to thyrocytes and a decrease in their functional activity in autoimmune thyroiditis. In a population study conducted by Q. Wu et al., it was shown that subclinical hypothyroidism (RR 0.68; 95% CI 0.58–0.93), overt hypothyroidism (RR 0 .75;95% CI 0.63–0.90), autoimmune thyroiditis (RR 0.47; 95% CI 0.35–0.65). In total, the prevalence of these diseases was almost two times less in the region with sufficient selenium supply compared to the selenium-deficient region (18% compared to 30.5%, p<0.001) [21].
But are selenium preparations able to prevent or at least slow down the development of autoimmune thyroiditis and, subsequently, hypothyroidism? There is currently no single answer to this question.
In studies of patients with autoimmune thyroiditis, the effect of selenium on the level of antithyroid antibodies (to thyroperoxidase (TPO) and thyroglobulin (TG)), thyroid function, echogenicity of thyroid tissue, and quality of life of patients was determined (Table 2). None of the studies evaluated the incidence of hypothyroidism, which is probably due to the short duration of the studies (no more than 12 months). Organic forms of selenium were mainly used, apparently due to their greater bioavailability.

Most authors [22–26] have found a statistically significant decrease in the level of anti-TPO antibodies after the use of selenium at doses of 83–200 µg/day. In a study by O. Turker et al. it was shown that the dose of 100 mcg/day is insufficient to reduce the level of antithyroid antibodies, while the dose of 200 mcg was determined to be optimal. On the other hand, D. Nacamulli showed a sustained decrease in TPO antibodies with 83 µg of selenium per day, and the effect persisted for 1 year. Only one study demonstrated a decrease in the level of anti-TG antibodies, while in most studies the level of these antibodies did not change significantly [26].
O. Turker D. et al. found an “escape” effect, since the decrease in the level of antibodies to TPO continued for 6 months. therapy with selenium, but by the 9th month. the level of antibodies increased again, although it did not reach the initial level [27]. However, in other studies, the effect of treatment was stable and lasted up to 12 months. the use of the drug.
But the effect on the level of antibodies was not confirmed in all studies against the background of taking the same doses of selenium (83–200 µg/day) [28, 29].
There was no effect of selenium on the level of TSH and thyroid hormones. Only in the study of D. Esposito was an increase in St. T ₃ and decrease in St. T ₄ in the group of patients taking selenium, while in the control group there was a decrease in the level of St. Т ₃ after 3 and 6 months. compared to the original. This result may reflect an increase in the activity of deiodinases and an increase in the conversion of T ₄ to T ₃ . The effect on the level of T ₃ appeared after 3 months. drug intake [28].
In the study of L. Yu in the group of patients with hypothyroidism, a weak negative correlation of selenium concentration in the blood with TSH was revealed. In addition, it was demonstrated that the concentration of interleukin-2 decreases against the background of selenium, which indicates a decrease in inflammation [26].
Some studies have assessed the severity of changes in thyroid tissue typical of autoimmune thyroiditis during ultrasound. In two of the three studies, an improvement in echostructure was found, which indirectly indicates a decrease in autoimmune inflammation. Such positive changes were revealed in studies that simultaneously demonstrated a decrease in the level of antibodies to thyroid tissue [22, 23]. D. Esposito noted the absence of changes in the ultrasound picture, while there was no effect on the level of antibodies [28].
Gartner and Nacamulli evaluated the quality of life of patients with autoimmune thyroiditis (AIT) while taking selenium. Both studies showed an improvement in the quality of life, and there was also a decrease in the level of antibodies to TPO [22, 23].
Some researchers have studied the effectiveness of combining selenium with other drugs that affect thyroid function. So, in patients with AIT and euthyroidism, who took a combination of selenium and myoinositol, which also affects thyroid function, there was a significant decrease in the level of both TSH and antithyroid antibodies, while in the comparison group, in which patients took only selenium at a dose of 83 mcg / days, no such changes were detected [29].
Thus, encouraging data have now been obtained on a decrease in the level of antithyroid antibodies in AIT with the help of selenium. However, additional studies are required to formulate recommendations on the regimen of the drug and the duration of treatment.
The effect of selenium on thyroid function was studied in pregnant women with elevated titers of anti-TPO antibodies. It is known that with an increased level of antibodies to TPO before pregnancy in women, the risk of postpartum thyroiditis and the development of hypothyroidism during pregnancy is significantly increased. The results of the use of 200 μg of selenomethionine during pregnancy were a decrease in the titer of antibodies to TPO, an improvement in the structure of the thyroid gland according to ultrasound, a decrease in the incidence of postpartum thyroiditis and permanent hypothyroidism in the postpartum period [30].
Thus, at present, the role of selenium in reducing the level of antithyroid antibodies, especially antibodies to TPO, can be considered proven, but the clinical significance of this phenomenon has not been proven. In addition, only one study determined the concentration of selenium in the blood before and during the administration of selenium preparations, which does not allow determining the initial deficiency of the microelement and replenishing it during the administration of the preparation. Currently, a study is underway on the effectiveness of selenium in patients with AIT with reduced thyroid function. The end point of the study is not only the level of antibodies to thyroid tissue, but also the dose of replacement therapy with levothyroxine sodium, and the quality of life of patients. It is planned to complete the study in 2018 [31].

Selenium and diffuse toxic goiter (DTG)

DTG belongs to the group of autoimmune thyroid diseases. In connection with the positive effect of selenium on the level of antithyroid antibodies, a study of its effect on the course of this disease is being carried out. V. Vrca studied the course of thyrotoxicosis with the addition of selenium to traditional therapy for DTG. A fixed combination of 60 micrograms of selenium was used with other antioxidants: vitamin E, vitamin C and beta-carotene. The study showed that in the group receiving a combined selenium-containing antioxidant drug simultaneously with methimazole, euthyroidism was achieved faster than in the group taking only methimazole [32]. But in a randomized study by M. Leo et al. no benefit was found for the combination of 166 μg selenium and methimazole over methimazole monotherapy [33]. In a similar study by J. Calissendorff, using 200 μg of selenomethionine in the treatment regimen for patients with thyrotoxicosis, a more pronounced decrease in the level of thyroid hormones and an increase in the level of TSH were demonstrated [34]. When comparing these studies, only one difference was revealed that could affect the result – in the study by J. Calissendorff, patients were with laboratory-confirmed selenium deficiency. It is possible that selenium has a positive effect on the treatment of thyrotoxicosis only when it is deficient, and when there is a sufficient level, it is pointless to add it to the treatment. But this hypothesis requires confirmation. In addition, perhaps it is the combination of selenium with other antioxidants (vitamins E and C) that has a positive effect.
In another study, selenium was added to methimazole in the treatment of patients with recurrent DTG. An accelerated achievement of euthyroidism and a pronounced decrease in the level of antibodies to TSH receptors were also shown. At the final visit, a large proportion of patients in the group treated with selenium did not have antibodies to TSH receptors, which improves the prognosis in the near future [35].
Another area of ​​research is the use of selenium in the treatment of endocrine ophthalmopathy (Graves’ disease). It is one of the clinical manifestations of DTG. This disease significantly affects the quality of life of patients, and the treatment regimens used are not always sufficiently effective and safe. S. Marcocci conducted a randomized double-blind study to study the effect of selenium and pentoxifylline on the course of endocrine ophthalmopathy. 152 patients with endocrine ophthalmopathy were divided into groups receiving selenium, pentoxifylline or placebo. The study used the inorganic compound sodium selenite at a dose of 100 mcg 2 times a day. Treatment continued for 6 months. followed by follow-up for 6 months. It was concluded that the use of selenium improved the quality of life of patients, slowed down the progression of endocrine ophthalmopathy after 6 months. treatment. The effect persisted for 6 months. observations. Pentoxifylline has not been proven effective [36]. Although the data are clearly insufficient, the international organization EUGOGO, based on this study, included selenium in its recommendations for the treatment of mild endocrine ophthalmopathy [37]. This is important because for severe forms, a treatment regimen with the use of glucocorticoids has been developed, and for mild forms, which sometimes significantly worsen the patient’s quality of life, no treatment was previously offered, but only observation.
Currently, the GRASS study is ongoing, planned for completion in 2018, which should answer the questions whether the addition of selenium to the therapy of Graves’ disease will accelerate the achievement of euthyroidism, reduce the risk of disease recurrence, and improve the quality of life of patients [38].
Of interest is a pilot study on the treatment of patients with subclinical thyrotoxicosis with a combination of selenium and L-carnitine. Subclinical thyrotoxicosis is much more common than manifest, and, according to various sources, ranges from 0.6 to 16%, depending on the diagnostic criteria, the age of the patients, and the provision of the region with iodine. The causes of subclinical thyrotoxicosis may be different: the onset of Graves’ disease, nodular or multinodular toxic goiter, thyrotoxic phase of thyroiditis, etc. But regardless of the causes, persistent subclinical thyrotoxicosis affects the quality of life of patients, and in elderly patients significantly increases the risk of cardiovascular diseases – mainly atrial fibrillation and thromboembolic complications. To date, no effective and safe treatment regimens have been developed for these patients. At a TSH level of 0.1-0.4 mU/L, observational tactics are recommended, while at a lower TSH level, treatment with small doses of thyreostatics and/or beta-blockers is used. This study was planned as a pilot study, and the number of patients was small (n=18), which allows only preliminary conclusions to be drawn. As a result of the use of 83 micrograms of selenium and 500 mg of L-carnitine for 1 month. managed to significantly increase the level of TSH to almost normal values, reduce the level of antibodies to TPO and TG, reduce the clinical manifestations of thyrotoxicosis, such as trembling, palpitations, weakness. The treatment lasted for 1 month, and after 1 month. observation after discontinuation of therapy, a return of hormonal parameters and clinical manifestations to the initial level was recorded, which demonstrated an insufficient duration of treatment. Side effects were not recorded. Of course, a larger study is required, but this pilot study gives hope for the development of an effective and safe regimen for the treatment of patients with subclinical thyrotoxicosis [39].

Selenium, diffuse and nodular goiter and thyroid cancer

Some researchers have studied the effect of selenium on the formation of goiter – both diffuse and nodular. Most of the studies are few, but it is suggested that there is an inverse relationship between blood and urine selenium levels and thyroid volume and hypoechogenicity. So, L. Rasmussen et al. found that a low concentration of selenium in the blood in combination with iodine deficiency is associated with an increased risk of developing both diffuse goiter and nodules in the thyroid gland [40].
The largest study in this area was conducted by Q. Wu et al. More than 6,000 people took part in the study. The aim of the study was to compare the prevalence of thyroid diseases in regions of China with different levels of selenium availability. It has been found that high selenium levels are associated with a lower incidence of goiter (RR 0.75, 95% CI 0.59–0.97) [21].
Thus, preliminary data have now been obtained on a greater prevalence of diffuse and nodular goiter in regions with low selenium intake. But studies are needed to confirm that selenium supplementation can prevent the development of AIT and multinodular goiter.
Several studies have examined the association of cancer and low levels of selenium in the blood and urine. It has been found that the incidence of cancer increases with selenium deficiency. A meta-analysis was conducted of 8 studies involving more than 1200 patients, which studied the relationship of the level of certain micronutrients (selenium, copper and magnesium) with thyroid cancer (TC). Patients with thyroid cancer have been shown to have reduced levels of selenium and magnesium and increased levels of copper compared to healthy controls [41]. J. Jonklaas, in his study of 65 patients who underwent thyroidectomy for thyroid cancer and nodular goiter, confirmed that selenium deficiency is associated with a high degree of cancer. The exact mechanisms of the effect of selenium deficiency on cancer development are still unknown, but it is assumed that the lack of selenoenzymes leads to an increase in free radicals that contribute to carcinogenesis and disease progression [42].

Selenium, general morbidity and mortality

Some studies have shown that there is a U-shaped relationship between the concentration of selenium in the blood and general morbidity, i.e., both a deficiency and an excess of selenium affect the incidence [43]. In other words, the supplementation of selenium is beneficial in the presence of selenium deficiency, but the use of additional selenium preparations in the absence of deficiency can lead to various side effects, such as hyperglycemia and accelerated progression of atherosclerosis [44, 45].
Mortality from all causes also increases with a deficiency or excess of selenium. A study involving more than 13,000 patients and lasting 12 years showed a weak positive association between selenium levels above 150 ng/mL and overall mortality, as well as mortality from cancer [46].

Practical application of selenium

Despite the fact that data on the effectiveness of selenium is rather contradictory, it is already used in real clinical practice. In Italy, endocrinologists were surveyed about their experience with selenium. 778 doctors took part in the survey. 85.2% of respondents indicated that they use selenium in the treatment of patients, and about 30% prescribe it often, the main nosology for prescribing selenium was AIT. Two-thirds of the respondents prescribed selenium for subclinical hypothyroidism in patients with AIT. One fifth of the respondents used this microelement in the treatment regimen for mild endocrine ophthalmopathy. Most physicians used doses of 100 to 200 μg of selenium per day [47].
An example of a selenium-containing agent is the dietary supplement Oksilik containing 50 µg of selenium. Oxylik also contains vitamins C and E, lycopene and β-carotene. It is the combination of selenium with other vitamins with antioxidant activity that has demonstrated its effectiveness in the treatment of autoimmune thyroid diseases [32]. This is probably due to the synergy of their action.
Oxilik has a high synergistic combination of antioxidants in doses corresponding to the physiological need for them.