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Selenium in medicine: Selenium Uses, Side Effects & Warnings

Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews


Selenium is an essential trace mineral found in soil, water, and some foods. It is an important factor in many body processes.

Selenium increases antioxidant effects in the body. Crab, fish, poultry, and wheat are generally good food sources. The amount of selenium in soil varies, and foods grown in different soils have different selenium levels. The Eastern Coastal Plain and Pacific Northwest have the lowest selenium levels in the US.

People commonly use selenium for selenium deficiency and to reduce the risk for high blood pressure during pregnancy. It is also used for prostate cancer, complications from statin drugs, abnormal cholesterol levels, cataracts, and many other conditions, but there is no good scientific evidence to support most of these uses. There is also no good evidence to support using selenium for COVID-19.

Uses & Effectiveness ?

Likely Effective for

  • Selenium deficiency. Taking selenium by mouth is effective for preventing selenium deficiency.

Possibly Effective for

  • A disease that causes underactive thyroid (autoimmune thyroiditis). Taking selenium by mouth daily along with thyroid hormone might benefit adults, but not children, with this condition.
  • A disorder that affects the bones and joints, usually in people with selenium deficiency (Kashin-Beck disease). Adding salt enriched with selenium to food can prevent Kashin-Beck disease in children. But selenium does not seem to improve joint pain or movement in children with Kashin-Beck disease.
  • A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Taking selenium 60-100 mcg by mouth daily for up to 6 months during pregnancy might reduce the risk of developing pre-eclampsia.

Possibly Ineffective for

  • Asthma. Taking selenium by mouth doesn’t seem to help asthma symptoms.
  • Eczema (atopic dermatitis). Taking yeast that is enriched with selenium by mouth daily for 12 weeks, alone or with vitamin E, does not improve eczema.
  • Bladder cancer. Taking selenium by mouth doesn’t seem to prevent bladder cancer.
  • Heart disease. Taking selenium by mouth doesn’t seem to reduce the risk of heart disease.
  • Colon cancer, rectal cancer. Taking selenium by mouth doesn’t seem to reduce the risk of colon or rectal cancer.
  • Diabetes. People who eat diets high in selenium and those who take selenium supplements for many years have an increased risk of type 2 diabetes. For people who already have diabetes, taking selenium by mouth does not improve blood sugar levels.
  • Abnormal levels of cholesterol or blood fats (dyslipidemia). Taking selenium by mouth does not improve cholesterol levels in people with dyslipidemia.
  • Infants born weighing less than 2500 grams (5 pounds, 8 ounces). Giving selenium by mouth or by IV does not appear to reduce the chance of death in low birth weight infants. IV products can only be given by a healthcare provider.
  • Lung cancer. Taking selenium by mouth, alone or with other nutrients, does not reduce the risk of lung cancer. But it might benefit people with low selenium levels.
  • Nonmelanoma skin cancer. Taking selenium by mouth doesn’t reduce the risk of getting a certain type of skin cancer called basal cell carcinoma. In fact, taking extra selenium might actually increase the risk of getting another type of skin cancer called squamous cell carcinoma.
  • Prostate cancer. Taking selenium by mouth does not reduce the risk of getting prostate cancer.
  • Scaly, itchy skin (psoriasis). Taking yeast enriched with selenium by mouth daily does not reduce symptoms of psoriasis.
  • Blood infection (sepsis). Giving selenium along with other nutrients by IV does not reduce the risk of death in people with sepsis. IV products can only be given by a healthcare provider.

There is interest in using selenium for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: Selenium is likely safe when taken in doses less than 400 mcg daily, short-term. But selenium is possibly unsafe when taken in high doses or for a long time. Taking doses above 400 mcg daily can increase the risk of developing selenium toxicity. Taking lower doses for a long time can increase the risk of developing diabetes.

Selenium can cause stomach discomfort, headache, and rash. High doses can cause hair loss, fatigue, nausea, vomiting, and weight loss. Extremely high doses can lead to organ failure and death.

Special Precautions and Warnings

When taken by mouth: Selenium is likely safe when taken in doses less than 400 mcg daily, short-term. But selenium is possibly unsafe when taken in high doses or for a long time. Taking doses above 400 mcg daily can increase the risk of developing selenium toxicity. Taking lower doses for a long time can increase the risk of developing diabetes.

Selenium can cause stomach discomfort, headache, and rash. High doses can cause hair loss, fatigue, nausea, vomiting, and weight loss. Extremely high doses can lead to organ failure and death. Pregnancy and breast-feeding: Selenium is possibly safe when used short-term in amounts that are not above 400 mcg daily. Selenium is possibly unsafe when taken by mouth in doses above 400 mcg daily. This dose might cause toxicity.

Children: Selenium is possibly safe when taken by mouth appropriately. Selenium seems to be safe when used short-term in doses below 45 mcg daily for infants up to age 6 months, 60 mcg daily for infants 7-12 months, 90 mcg daily for children 1-3 years, 150 mcg daily for children 4-8 years, 280 mcg daily for children 9-13 years, and 400 mcg daily for children age 14 years and older.

Autoimmune diseases: Selenium might stimulate the immune system. People with autoimmune diseases such as multiple sclerosis, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and other should avoid taking selenium supplements.

Hemodialysis: Blood levels of selenium can be low in people on hemodialysis. Selenium supplements might be needed for some people.

Under-active thyroid (hypothyroidism): Taking selenium can worsen hypothyroidism, especially in people with iodine deficiency. In this case, you should take iodine along with selenium. Check with your healthcare provider before taking selenium supplements.

Fertility problems in males: Selenium might decrease the ability of sperm to move, which could reduce fertility.

Skin cancer: In people who have had nonmelanoma skin cancer, long-term use of selenium supplements might slightly increase the risk of cancer returning. Avoid long-term use of selenium supplements if you have ever had skin cancer.

Surgery: Selenium might increase the risk of bleeding during and after surgery. Stop taking selenium at least 2 weeks before a scheduled surgery.

Interactions ?

    Moderate Interaction

    Be cautious with this combination

  • Selenium might slow blood clotting. Taking selenium along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

  • Taking niacin along with the drug simvastatin can increase good cholesterol levels. Taking niacin plus simvastatin along with selenium and other antioxidants can decrease the effects of niacin and simvastatin on good cholesterol levels. It is unknown if selenium alone decreases the effects of niacin plus simvastatin on good cholesterol levels.

  • Selenium might reduce how quickly the body breaks down sedative medications. Taking selenium with these medications might increase the effects and side effects of these medications.

  • Selenium might slow blood clotting. Selenium might also increase the effects of warfarin in the body. Taking selenium along with warfarin might increase the chances of bruising and bleeding.

  • Selenium can increase the activity of the immune system. Some medications, such as those used after a transplant, decrease the activity of the immune system. Taking selenium along with these medications might decrease the effects of these medications.

    Minor Interaction

    Be watchful with this combination

  • Taking birth control pills might increase blood levels of selenium. But it’s not clear if this is a real concern.

  • Gold salts bind to selenium and decrease selenium in parts of the body. This might decrease the normal activity of selenium, possibly resulting in symptoms of selenium deficiency.


Selenium is an essential trace mineral found in foods, including crab, fish, poultry, and wheat. The amount of selenium in soil varies, so foods grown in different soils have different selenium levels. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). The RDA is 55 mcg daily for all people 19 years and older. While pregnant, the RDA is 60 mcg daily. While breastfeeding, the RDA is 70 mcg daily. In children, the RDA depends on age.

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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
© Therapeutic Research Faculty 2020.

7 Science-Based Health Benefits of Selenium

Selenium is a mineral you can consume by eating many foods. It can help support the healthy functioning of your body, including your metabolism, immune system, and thyroid function.

Though you may have never heard of selenium, this amazing nutrient is vital to your health.

Selenium is an essential mineral, meaning it must be obtained through your diet.

It’s only needed in small amounts but plays a major role in important processes in your body, including your metabolism and thyroid function.

This article outlines 7 health benefits of selenium, all backed by science.

Antioxidants are compounds in foods that prevent cell damage caused by free radicals.

Free radicals are normal byproducts of processes like metabolism that are formed in your body daily.

They often get a bad rap, but free radicals are essential for your health. They perform important functions, including protecting your body from disease.

However, things like smoking, alcohol use, and stress can cause an excess of free radicals. This leads to oxidative stress, which damages healthy cells (1).

Oxidative stress has been linked to chronic conditions like heart disease, Alzheimer’s, and cancer, as well as premature aging and the risk of stroke (2, 3, 4, 5, 6).

Antioxidants like selenium help reduce oxidative stress by keeping free radical numbers in check (7).

They work by neutralizing excess free radicals and protecting cells from damage caused by oxidative stress.

Summary Selenium is a powerful antioxidant that fights oxidative stress and
helps defend your body from chronic conditions, such as heart disease and

In addition to decreasing oxidative stress, selenium may help lower the risk of certain cancers.

This has been attributed to selenium’s ability to reduce DNA damage and oxidative stress, boost your immune system, and destroy cancer cells (8).

A review of 69 studies that included over 350,000 people found that having a high blood level of selenium was associated with a lower risk of certain types of cancer, including breast, lung, colon, and prostate cancers (9).

It’s important to note that this effect was only associated with selenium obtained through foods, not supplements.

However, some research suggests that supplementing with selenium may reduce side effects in people undergoing radiation therapy.

For example, one study found that oral selenium supplements improved overall quality of life and reduced radiation-induced diarrhea in women with cervical and uterine cancer (10).

Summary Higher blood levels of selenium may protect against certain cancers,
while supplementing with selenium may help improve quality of life in people
undergoing radiation therapy.

A diet rich in selenium may help keep your heart healthy, as low selenium levels have been linked to an increased risk of heart disease.

In an analysis of 25 observational studies, a 50% increase in blood selenium levels was associated with a 24% reduction in the risk of heart disease (11).

Selenium may also lower markers of inflammation in your body⁠ — one of the main risk factors for heart disease.

For example, a review of 16 controlled studies including over 433,000 people with heart disease showed that taking selenium supplements decreased levels of the inflammatory marker C-reactive protein (CRP).

Additionally, it increased levels of glutathione peroxidase, a powerful antioxidant (12).

This indicates that selenium may help lower heart disease risk by reducing inflammation and oxidative stress in your body. Oxidative stress and inflammation have been linked to atherosclerosis, or the buildup of plaque in arteries.

Atherosclerosis can lead to dangerous health problems like strokes, heart attacks, and heart disease (13).

Incorporating selenium-rich foods into your diet is a great way to keep levels of oxidative stress and inflammation to a minimum.

Summary Selenium may help keep your heart healthy by keeping oxidative stress
in check and reducing your risk of heart disease.

Alzheimer’s disease is a devastating condition that causes memory loss and negatively affects thinking and behavior. It’s the sixth-leading cause of death in the United States.

The number of people with Alzheimer’s disease is growing. Thus, finding ways to prevent this degenerative disease is imperative.

Oxidative stress is believed to be involved in both the onset and progression of neurological diseases like Parkinson’s, multiple sclerosis, and Alzheimer’s (14).

Several studies have shown that patients with Alzheimer’s disease have lower blood levels of selenium (15, 16).

Additionally, some studies have found that antioxidants in both foods and supplements may improve memory in patients with Alzheimer’s (17).

One small study found that supplementing with one selenium-rich Brazil nut per day improved verbal fluency and other mental functions in patients with mild cognitive impairment (18).

What’s more, the Mediterranean diet, which is rich in high-selenium foods like seafood and nuts, has been associated with a lower risk of developing Alzheimer’s disease (19, 20).

Summary A diet rich in selenium may help prevent mental decline and improve
memory loss in people with Alzheimer’s disease.

Selenium is important for the proper functioning of your thyroid gland. In fact, thyroid tissue contains a higher amount of selenium than any other organ in the human body (21).

This powerful mineral helps protect the thyroid against oxidative damage and plays an essential role in the production of thyroid hormones.

A healthy thyroid gland is important, as it regulates your metabolism and controls growth and development (22).

Selenium deficiency has been associated with thyroid conditions like Hashimoto’s thyroiditis, a type of hypothyroidism in which the immune system attacks the thyroid gland.

An observational study including over 6,000 people found that low serum levels of selenium were associated with an increased risk of autoimmune thyroiditis and hypothyroidism (23).

Additionally, some studies have shown that selenium supplements may benefit people with Hashimoto’s disease.

One review concluded that taking selenium supplements daily for three months resulted in lower thyroid antibodies. It also led to improvements in mood and general well-being in those with Hashimoto’s disease (24).

However, more research is needed before selenium supplements can be recommended for those with Hashimoto’s disease.

Summary Selenium protects the thyroid gland from oxidative stress and is
necessary for thyroid hormone production. Selenium may help people with
Hashimoto’s disease and other types of thyroid disease, but more research is

Your immune system keeps your body healthy by identifying and fighting off potential threats. These include bacteria, viruses, and parasites.

Selenium plays an important role in the health of your immune system. This antioxidant helps lower oxidative stress in your body, which reduces inflammation and enhances immunity.

Studies have demonstrated that increased blood levels of selenium are associated with enhanced immune response.

On the other hand, deficiency has been shown to harm immune cell function and may lead to a slower immune response (25).

Studies have also associated deficiency with an increased risk of death and disease progression in people with HIV, while supplements have been shown to lead to fewer hospitalizations and an improvement in symptoms for these patients (26).

Additionally, selenium supplements may help strengthen the immune system in people with influenza, tuberculosis, and hepatitis C (27).

Summary Selenium is crucial for the health and proper functioning of your
immune system. Higher levels of selenium may help boost the immune systems of
people with HIV, influenza, tuberculosis, and hepatitis C.

Asthma is a chronic disease that affects the airways that carry air in and out of the lungs.

These airways become inflamed and begin to narrow, causing symptoms like wheezing, shortness of breath, chest tightness, and coughing (28).

Asthma has been associated with increased levels of oxidative stress and inflammation in the body (29).

Due to selenium’s ability to reduce inflammation, some studies suggest that this mineral may help reduce asthma-related symptoms.

Research suggests that people who have asthma have lower blood levels of selenium.

In fact, one study showed that asthmatic patients with higher levels of blood selenium had better lung function than those with lower levels (30).

Selenium supplements may also help reduce asthma-related symptoms.

For example, one study found that giving people with asthma 200 mcg of selenium per day reduced their use of the corticosteroid medications used to control their symptoms (31).

However, research in this area is conflicting, and larger studies are needed to fully understand selenium’s role in the development and treatment of asthma (32).

Summary Selenium may benefit people with asthma due to its ability to lower
inflammation in the body. However, more research is needed.

Fortunately, many healthy foods are high in selenium.

The following foods are great sources (33), (34):

  • Oysters: 238% of the DV in 3 ounces (85 grams)
  • Brazil nuts: 174% of the DV in one
    nut (5 grams)
  • Halibut: 171% of the DV in 6 ounces
    (159 grams)
  • Yellowfin tuna: 167% of the DV in 3 ounces
    (85 grams)
  • Eggs: 56% of the DV in 2
    large eggs (100 grams)
  • Sardines: 46% of the DV in 4
    sardines (48 grams)
  • Sunflower seeds: 27% of the DV in 1 ounce
    (28 grams)
  • Chicken breast: 12% of the DV in 4
    slices (84 grams)
  • Shiitake mushrooms: 10% of the DV in 1 cup
    (97 grams)

The amount of selenium in plant-based foods varies depending on the selenium content of the soil in which they were grown.

Thus, selenium concentrations in crops depend largely on where they are farmed.

For example, one study showed that the selenium concentration in Brazil nuts varied widely by region. While a single Brazil nut from one region provided up to 288% of the recommended intake, others provided only 11% (35).

Therefore, it’s important to consume a varied diet that includes more than one good source of this important mineral.

rich in selenium include seafood, nuts, and mushrooms. It’s important to
consume a variety of foods that contain this mineral, as selenium content can
vary depending on growing conditions.

Although selenium is necessary for good health, getting too much can be dangerous. In fact, consuming high doses of selenium can be toxic and even fatal.

While selenium toxicity is rare, it’s important to stay close to the recommended amount of 55 mcg per day and never exceed the tolerable upper limit of 400 mcg per day (36).

Brazil nuts contain a very high amount of selenium. Consuming too many could lead to selenium toxicity.

However, toxicity is more likely to happen from taking supplements rather than eating selenium-containing foods.

Signs of selenium toxicity include:

  • hair loss
  • dizziness
  • nausea
  • vomiting
  • facial flushing
  • tremors
  • muscle soreness

In severe cases, acute selenium toxicity can lead to serious intestinal and neurological symptoms, heart attack, kidney failure, and death (37).

SummaryWhile selenium toxicity is
rare, overconsumption of this mineral through diet or supplements can have
dangerous side effects.

Selenium is a powerful mineral that is essential for the proper functioning of your body.

It plays a critical role in metabolism and thyroid function and helps protect your body from damage caused by oxidative stress.

What’s more, selenium may help boost your immune system, slow age-related mental decline, and even reduce your risk of heart disease.

This micronutrient can be found in a wide variety of foods, from oysters to mushrooms to Brazil nuts.

Adding more selenium-rich foods to your diet is an excellent way to maintain good health.

Antioxidant selenium: useful properties | Anti-Age Expert Blog

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Functions of selenium in the body

Selenium forms important proteins that strengthen the immune system and prevent cell damage. It enhances the function of vitamin E and vitamin C as protective vitamins. Along with iodine, selenium produces thyroid hormones that increase sperm production and support nervous system function. Without selenium, the liver and pancreas would not be able to carry out their functions of digestion and regulate blood glucose.

In addition, selenium helps the body bind lead from heavy metals, so that they cannot harm the body and are more easily excreted from the body.

Benefits of selenium for the body

Selenium is part of more than 30 proteins and 200 hormones and enzymes. It has a wide range of health benefits, including the ability to protect against certain heart conditions and boost the strength of the immune system.

Here are just a few of the beneficial properties of selenium:

  • Has antioxidant properties. The antioxidant potential of selenium has been found to be vital in protecting overall health, as free radicals in the body can affect us in several ways. They can weaken or kill cells in any organ system, leading to heart disease, kidney function, or digestion, for example. Excessive oxidation in the body can cause metabolic syndrome, hormonal imbalances, and premature aging. The antioxidant properties of selenium may prove beneficial in protecting against oxidative stress and preventing such health problems.

  • Protects against cancer. Selenium is rich in antioxidant and anti-inflammatory properties. It is an important part of various cellular processes, including the body’s response to malignant activity. A study published in the journal Human Biology and Health found that a normal intake of this mineral can lead to a reduction in cancer cell formation, especially for prostate, colon, and lung cancers. A 2013 review study in the journal Nutrients found that in addition to its potential as a cancer preventative, selenium may also be an anti-metastatic element, thereby helping in the later stages of cancer progression.

  • Increases immunity. Science has proven that selenium is important for stimulating antibodies, which are elements of the immune system – they find and destroy viral, bacterial, fungal and protozoan foreign bodies that cause diseases and infections.

  • Reduces inflammation. This trace element not only strengthens the immune system, but also protects the body from fatigue and the feeling of approaching old age. Hormone and Metabolic Research has shown that selenium reduces oxidative stress, which often occurs around joints and bones, manifesting itself in various inflammatory conditions such as rheumatoid arthritis, gout, psoriasis, lupus, pain and weakness associated with eczema. By reducing inflammation in these vital parts of the body, you can stay active and healthy for years to come.

  • Improves thyroid health. According to a 2017 study, the thyroid contains more selenium per gram of tissue than any other organ in the body. It normalizes the metabolism of hormones, and therefore maintaining optimal levels of selenium can help ensure the normal functioning of the thyroid gland and prevent its diseases.

  • Relieves asthma symptoms. Selenium deficiency is considered to be one of the causes of asthma, therefore special supplements can be used as a means to alleviate this respiratory disease.

  • Increases fertility. Selenium promotes sperm motility and increased blood flow in the body. A 2017 study shows that it may play a role in improving sperm health and male fertility.

  • Improves mental health and mood. Cognitive decline is associated with the activity of free radicals in the nerve cortex, destroying pathways and preventing the proper functioning of nerve impulses. According to research, selenium can help prevent the onset of Alzheimer’s and improve mental health and overall mood by neutralizing free radicals before they affect you.

  • Supports heart health. Selenium acts as a blood thinner, which reduces the chance of blood clots and also reduces the amount of LDL cholesterol that forms plaque in the arteries and blood vessels. This plaque can lead to atherosclerosis, heart attacks, and strokes, which is why selenium is a powerful booster of overall heart health.

  • Good for hair. It is believed that a good selenium content can reduce hair loss and excessive scalp dryness that leads to dandruff. In a study cited in the Journal of the American Academy of Dermatology, selenium sulfide shampoo was effective in treating moderate to severe dandruff.

“Selenium has an anti-inflammatory, anti-atherosclerotic effect, promotes hair growth, and prevents the aging process in general. It reduces the negative effects of adverse environmental factors and protects the heart tissue from oxygen starvation, prevents degenerative changes in the brain, and also inhibits the development of autoimmune processes, and prevents the development of cancer.”

Dorina Alekseevna Donich

MD, obstetrician-gynecologist, bioregenerative and anti-aging medicine doctor
Experience: 25 years

Selenium Daily Value

How Much Selenium Should You Take? In this case, it is especially important to know the correct dosage, since an excess of this trace element can be harmful to health, since selenium is toxic.

Thus, the daily intake of selenium depends on age:

  • Toddlers need 20 mcg/day.

  • Children (4 to 8 years old) – 30 mcg / day.

  • Children (9 to 14 years old) – 40 mcg / day.

  • Adults (over 15 years old) – 55 mcg / day.

  • Pregnant women – 60 mcg / day.

  • Lactating women – 70 mcg / day.

The recommended dose includes the total amount of selenium you should be getting from food and any supplements. Most people can get their selenium levels from food.

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Selenium excess

The safe upper limit for selenium for adults is 400 micrograms per day. Anything above is considered an overdose.

Symptoms of poisoning include:

  • Bad breath;

  • gastrointestinal disorders;

  • Heat;

  • Nausea;

  • kidney problems;

  • Fatigue;

  • Irritability;

  • Difficulty concentrating;

  • Cirrhosis of the liver;

  • Pulmonary edema and even death.

Be careful not to take selenium supplements if you are already on a diet rich in this element. They are also best avoided by people with a high risk of skin cancer.

In addition, selenium can interact with medications such as certain antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statins, and birth control pills.

Selenium deficiency

Among healthy people, selenium deficiency is rare. But some health conditions, such as HIV, Crohn’s disease, and others, are associated with low levels of this micronutrient. People who are fed intravenously are also usually deficient in selenium. Doctors sometimes recommend that people with these conditions take selenium supplements.

Diseases due to selenium deficiency

A slight lack of selenium can, for example, cause white spots on the nails and noticeably thin, colorless hair or even hair loss.

A more pronounced selenium deficiency affects, for example, the thyroid gland and the immune system, as well as other areas and functions of the body.

Typical symptoms of selenium deficiency:

  • Impaired thyroid function;

  • fertility problems in men;

  • Susceptibility to infections;

  • Weight loss;

  • Constipation;

  • Headache;

  • memory disorders;

  • sleep disorders;

  • Joint pain;

  • Muscle diseases (myopathies).

In addition, persistent selenium deficiency can cause a specific clinical picture – Keshan disease, which affects the heart muscle, as well as Kashin-Beck disease, which is characterized by changes in the joints and reduced bone growth. Both diseases are found almost exclusively in some regions of China where the soil is extremely poor in selenium.

Selenium has also been studied to treat dozens of conditions. They range from asthma to arthritis, from dandruff to infertility. However, the results are not always convincing.

Replenishment of selenium in the body

The following foods remain the best sources of selenium for humans:

  • Vegetable. These are, in particular, Brazil nuts, which hold the record for the content of this mineral.

    Other plant sources of selenium are spinach, mushrooms, sunflower seeds, and chia seeds, as well as foods made from grains grown in selenium-rich soils (cereals, brown rice, white bread, and pasta).

  • Fish and seafood. Halibut, tuna, crabs, sea bass, herring and lobsters are very rich in selenium.

  • Animal products: These include animal kidneys, grass-fed beef, chicken breast, turkey and eggs.

Special supplements with selenium should be taken only as directed by a doctor.


  • Selenium is toxic in large quantities, but it is necessary for the normal functioning of the body.

  • Selenium has a wide range of health benefits from immune boosting to anti-carcinogenic effects.

  • The daily intake of selenium depends on age.

  • The safe upper limit for selenium for adults is 400 micrograms per day.

  • Larger amounts may cause symptoms of intoxication.

  • Healthy people are rarely deficient in selenium.

  • Its best sources are plant foods and some animal products.

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  1. Kieliszek, M.; Błażejak, S. Current knowledge on the importance of selenium in food for living organisms: A review. Molecules 2016, 21, 609.

  2. Duntas, L. H.; Benvenga, S. Selenium: An element for life. Endocrine 2015, 48, 756–775.

  3. Pedrero, Z.; Madrid, Y. Novel approaches for selenium speciation in foodstuffs and biological specimens: A review. Anal. Chim. Acta 2009, 634, 135–152.

  4. Beck, M.A.; Levander, O.A.; Handy, J. Selenium deficiency and viral infection. J. Nutr. 2003, 133, 1463-1467.

  5. Dennert G, Zwahlen M, Brinkman M, Vinceti M, Zeegers MP, Horneber M. Selenium for preventing cancer. Sao Paulo Medical Journal. 2012;130(1).

  6. Vinceti M, Filippini T, Del Giovane C, Dennert G, Zwahlen M, Brinkman M, Zeegers MP, Horneber M, D’Amico R, Crespi CM. Selenium for preventing cancer. Cochrane database of systematic reviews. 2018(1).

  7. Winther KH, Bonnema SJ, Cold F, Debrabant B, Nybo M, Cold S, Hegedüs L. Does selenium supplementation affect thyroid function? Results from a randomized, controlled, double-blinded trial in a Danish population. Eur J Endocrinol. 2015 Jun 1;172(6):657-67.

Selenium – essential trace element

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November 21

Selenium (m.w. 78.96) is a trace element vital for humans. It is important for thyroid function, normal functioning of the immune, reproductive, cardiovascular, and nervous systems. More than 30 biologically active selenium-containing proteins have been described; it is part of the human glutathione peroxidase and iodothyronine deiodinase enzymes. It is believed that selenium is functionally related to vitamin E. As a natural antioxidant, selenium compounds are used in medicine for the treatment and prevention of many diseases, in dermatology and cosmetology, therapeutic selenium-containing shampoos, soaps, gels, and creams are used.

In terms of biochemical properties, it is similar to sulfur – selenium replaces sulfur in cysteine, the resulting selencysteine ​​is considered a special amino acid with its own characteristic properties. Selenium comes from food, mainly in the form of plant selenomethionine, which obtain this element from the soil. The content of selenium in blood plasma and other biological fluids of the body varies widely depending on the conditions (the concentration of selenium in food and water). In blood plasma, about 50-60% of selenium is associated with selenium protein P, about 30% is part of glutathione peroxidase, the rest of selenium is included in albumin in the form of selenmethionine. Selenium is metabolized to dimethyl selenium, which is excreted through the lungs. The main route of excretion of selenium from the body is with urine. Plasma selenium levels decrease during the acute phase response of the body to inflammation and infection.

Selenium deficiency can be associated with a lack of it in the diet, as well as eating and digestion disorders. Severe selenium deficiency is associated with Keshan disease (an endemic cardiomyopathy found in the Keshan region of China, characterized by selenium deficiency in the soil), along with other independent factors, Kashin-Bek disease (multiple joint damage associated with an imbalance of minerals, an endemic disease described in China and adjacent regions of Russia), pathological changes that occur with artificial nutrition with a low selenium content. Borderline selenium deficiency can presumably be involved in changes in thyroid, immune, reproductive functions, mental disorders, pathogenesis of cardiovascular diseases, changes in the virulence of viruses, and a decrease in the body’s defense against certain types of cancer. In excess concentration, selenium can exhibit toxic properties. Symptoms of toxic effects of excess selenium include garlic breath, urine, metallic taste, headaches, nausea, hair loss, and damaged nails. Sensory loss, convulsions, pneumonia, pulmonary edema, and circulatory collapse are possible. Cases of toxic effects of selenium are described not only during exposure to selenium associated with industrial production, but also during its self-administration.

In general, serum or plasma studies accurately reflect the status of selenium in the body and the adequacy of its recent intake (provided that changes are known against the background of an acute phase response). To assess the level of selenium toxicity, it is advisable to examine 24-hour urine, the concentration of selenium in which, depending on the geographical source of food consumed, can range from 20 to 1000 µg/L. Hair selenium studies are useful for assessing long-term selenium intake (medicated shampoos and other hair care products may contain selenium and cause extrinsic contamination of the sample).


  1. Botsiev T.O., Kubalova L.M. Biological role of selenium and its compounds // International Student Scientific Bulletin. – 2015. – No. 3-4.
  2. Kokhan S.T., Fefelova E.V., Maksimenya M.V., Tereshkov P.P., Krivosheeva E.M., Pateyuk A.V., Shantanova L.N. Restoration of the antioxidant and immune protection of the body with selenium-containing agents in experimental hyposelenosis // Fundamental research. – 2012. – No. 11-4. – S. 837-841.


The information in this section should not be used for self-diagnosis or self-treatment. In case of pain or other exacerbation of the disease, only the attending physician should prescribe diagnostic tests. For diagnosis and proper treatment, you should contact your doctor.
For a correct assessment of the results of your analyzes over time, it is preferable to do studies in the same laboratory, since different laboratories may use different research methods and units of measurement to perform the same analyzes.


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