Selenium in Medicine: Essential Benefits, Uses, and Potential Risks
What are the key benefits of selenium in medicine. How does selenium function as an antioxidant. What are the recommended dosages and potential side effects of selenium supplementation. Where can selenium be found naturally in foods. How does selenium impact various health conditions.
The Vital Role of Selenium in Human Health
Selenium, a trace mineral found in soil and water, plays a crucial role in human metabolism despite being required in minimal amounts. This essential nutrient has garnered significant attention in the medical community due to its potent antioxidant properties, which help protect cells from damage caused by free radicals.
While selenium deficiencies are relatively uncommon in healthy individuals in the United States, certain health conditions such as HIV, Crohn’s disease, and situations requiring intravenous feeding can lead to low selenium levels. In these cases, healthcare providers may recommend selenium supplementation to maintain optimal health.
Selenium’s Antioxidant Action
How does selenium function as an antioxidant? Selenium is incorporated into proteins to create selenoproteins, which are powerful antioxidant enzymes. These selenoproteins help neutralize harmful free radicals in the body, potentially reducing oxidative stress and inflammation. This antioxidant action is believed to contribute to selenium’s potential health benefits, including support for immune function and thyroid health.
Selenium and Cancer: Mixed Evidence and Ongoing Research
The relationship between selenium and cancer prevention has been a subject of extensive research, with mixed results. While some studies initially suggested that selenium supplements might reduce the risk of prostate cancer, subsequent research has largely failed to confirm this benefit.
Is selenium effective in preventing other types of cancer? Current evidence indicates that selenium supplementation does not appear to affect the risk of colorectal or lung cancer. However, it’s important to note that some studies have raised concerns about a potential increase in the risk of non-melanoma skin cancer associated with selenium supplementation.
Selenium and Prostate Cancer
What does the latest research say about selenium and prostate cancer? While early studies showed promise, more recent and comprehensive research has not demonstrated a significant benefit of selenium supplementation in reducing prostate cancer risk. As a result, selenium is not currently recommended as a standalone preventive measure for prostate cancer.
Recommended Dietary Allowances and Safe Upper Limits
The recommended dietary allowance (RDA) for selenium varies depending on age, gender, and life stage. Most people can meet their selenium requirements through a balanced diet without the need for supplementation.
- Children 1-3 years: 20 micrograms/day
- Children 4-8 years: 30 micrograms/day
- Children 9-13 years: 40 micrograms/day
- Adults and children 14 and up: 55 micrograms/day
- Pregnant women: 60 micrograms/day
- Breastfeeding women: 70 micrograms/day
What is the safe upper limit for selenium intake? The tolerable upper intake level for selenium in adults is set at 400 micrograms per day. Consuming amounts above this level is considered an overdose and may lead to adverse effects.
Natural Sources of Selenium in Diet
Selenium content in foods can vary widely depending on the selenium concentration in the soil where plants are grown or animals are raised. However, several foods are consistently good sources of this essential mineral:
- Nuts, particularly Brazil nuts and walnuts
- Seafood, including tuna, cod, red snapper, and herring
- Beef and poultry
- Whole grains
Why are whole foods considered the best sources of selenium? Whole foods not only provide selenium but also offer a complex array of nutrients that work synergistically in the body. Additionally, selenium may be partially destroyed during food processing, making unprocessed foods a more reliable source.
Potential Side Effects and Interactions of Selenium Supplementation
When taken at normal doses, selenium supplements typically do not cause side effects in most individuals. However, exceeding the recommended dosage can lead to selenium toxicity, which may manifest as:
- Bad breath
- Fever
- Nausea
- Liver and kidney problems
- Heart issues
In extreme cases, selenium overdose can be life-threatening. It’s crucial to adhere to recommended dosages and consult a healthcare provider before starting any new supplement regimen.
Selenium Interactions with Medications
Can selenium interact with other medications? Yes, selenium may interact with various medicines and supplements, including:
- Certain antacids
- Chemotherapy drugs
- Corticosteroids
- Niacin
- Cholesterol-lowering statin drugs
- Birth control pills
Individuals taking these medications should consult their healthcare provider before using selenium supplements to avoid potential adverse interactions.
Selenium in Pregnancy and Thyroid Health
Selenium plays a significant role in maternal and fetal health during pregnancy. Some studies suggest that adequate selenium intake may help reduce the risk of pregnancy complications, particularly pre-eclampsia.
How does selenium impact thyroid function? Selenium is essential for the proper functioning of the thyroid gland. It is a component of enzymes involved in thyroid hormone metabolism. Some research indicates that selenium supplementation, when used in conjunction with thyroid hormone therapy, may benefit adults with autoimmune thyroiditis, a condition that causes an underactive thyroid.
Selenium and Pre-eclampsia Prevention
Can selenium supplementation reduce the risk of pre-eclampsia? Some studies have shown that taking 60-100 micrograms of selenium daily for up to 6 months during pregnancy might help reduce the risk of developing pre-eclampsia, a serious pregnancy complication characterized by high blood pressure and protein in the urine. However, more research is needed to establish definitive guidelines.
Selenium’s Potential in Other Health Conditions
Researchers have investigated selenium’s potential benefits in a wide range of health conditions, including:
- Asthma
- Arthritis
- Dandruff
- Infertility
- Kashin-Beck disease (a disorder affecting bones and joints)
- Cataracts
- Abnormal cholesterol levels
While some studies have shown promise, results for many of these conditions remain inconclusive, and more research is needed to establish selenium’s efficacy in these areas.
Selenium and Kashin-Beck Disease
How does selenium supplementation affect Kashin-Beck disease? In regions where Kashin-Beck disease is prevalent due to selenium-deficient soil, adding selenium-enriched salt to food has shown promise in preventing the condition in children. However, selenium supplementation does not appear to improve joint pain or movement in children already affected by the disease.
Selenium and COVID-19: Current Understanding
In the wake of the COVID-19 pandemic, researchers have explored the potential role of various nutrients, including selenium, in supporting immune function and potentially impacting disease outcomes.
Is there evidence supporting selenium use for COVID-19? As of now, there is no strong scientific evidence supporting the use of selenium specifically for the prevention or treatment of COVID-19. While selenium is important for overall immune function, its direct impact on COVID-19 outcomes remains unclear and requires further research.
Selenium’s Role in Immune Function
How does selenium contribute to immune health? Selenium is crucial for the proper functioning of the immune system. It supports the production and activity of immune cells, including T-cells and natural killer cells. While this general immune support is beneficial, it doesn’t necessarily translate to specific protection against particular viruses or diseases.
Considerations for Selenium Supplementation
Before considering selenium supplementation, it’s important to evaluate your individual needs and potential risks. While selenium is essential for health, the margin between adequate intake and potential toxicity is relatively narrow.
Who might benefit from selenium supplements? Individuals with conditions that impair selenium absorption, those living in selenium-deficient areas, or those with specific health conditions might benefit from supplementation. However, it’s crucial to consult a healthcare provider before starting any new supplement regimen.
Risks for Specific Populations
Are there groups that should be cautious about selenium supplementation? Yes, certain populations should be particularly careful with selenium intake:
- Individuals at high risk for skin cancer, as some studies suggest selenium might increase the risk of non-melanoma skin cancer
- People taking medications that may interact with selenium
- Those living in areas with naturally high selenium levels in soil and water
For these groups, careful monitoring of selenium intake and consultation with a healthcare provider is essential.
Future Directions in Selenium Research
As our understanding of selenium’s role in human health continues to evolve, researchers are exploring new areas of potential benefit and refining our knowledge of optimal intake levels.
What are some promising areas of selenium research? Current and future studies are likely to focus on:
- The role of selenium in cognitive function and neurodegenerative diseases
- Selenium’s impact on cardiovascular health
- The potential of selenium-enriched foods in addressing deficiencies in vulnerable populations
- The interaction between selenium and other nutrients in overall health maintenance
As research progresses, our understanding of selenium’s optimal use in medicine and public health strategies may be refined, potentially leading to more targeted recommendations for supplementation and dietary intake.
Personalized Nutrition and Selenium
How might advances in personalized nutrition impact selenium recommendations? As the field of nutrigenomics grows, researchers are investigating how individual genetic variations might affect selenium metabolism and requirements. This could lead to more personalized recommendations for selenium intake based on an individual’s genetic profile, overall health status, and environmental factors.
In conclusion, while selenium plays a crucial role in human health, its use as a supplement requires careful consideration. Most individuals can meet their selenium needs through a balanced diet rich in whole foods. For those considering supplementation, it’s essential to consult with a healthcare provider to determine individual needs and potential risks. As research continues, our understanding of selenium’s role in health and disease prevention will undoubtedly expand, potentially opening new avenues for its use in medicine and public health strategies.
Benefits, Uses, Side Effects, Dosage, and More
Written by R. Morgan Griffin
Medically Reviewed by Jennifer Robinson, MD on May 01, 2023
- Why do people take selenium?
- How much selenium should you take?
- Can you get selenium naturally from foods?
- What are the risks of taking selenium?
Selenium is a mineral found in the soil. Selenium naturally appears in water and some foods. While people only need a very small amount, selenium plays a key role in their metabolism.
Selenium has attracted attention because of its antioxidant properties. Antioxidants protect cells from damage. Evidence that selenium supplements may reduce the odds of prostate cancer has been mixed, but most studies suggest there is no real benefit. Selenium does not seem to affect the risk of colorectal or lung cancer. But beware: some studies suggest that selenium may increase the risk of non-melanoma skin cancer.
Among healthy people in the U. S., selenium deficiencies are uncommon. But some health conditions — such as HIV, Crohn’s disease, and others — are associated with low selenium levels. People who are fed intravenously are also at risk for low selenium. Doctors sometimes suggest that people with these conditions use selenium supplements.
Selenium has also been studied for the treatment of dozens of conditions. They range from asthma to arthritis to dandruff to infertility. However, the results have been inconclusive.
The recommended dietary allowance (RDA) includes the total amount of selenium you should get from foods and from any supplements you take. Most people can get their RDA of selenium from food.
In some studies to determine if selenium could aid in prostate cancer prevention, men took 100 micrograms daily.
The safe upper limit for selenium is 400 micrograms a day in adults. Anything above that is considered an overdose.
Group | Recommended Dietary Allowance |
Children 1-3 | 20 micrograms/day |
Children 4-8 | 30 micrograms/day |
Children 9-13 | 40 micrograms/day |
Adults and children 14 and up | 55 micrograms/day |
Pregnant women | 60 micrograms/day |
Breastfeeding women | 70 micrograms/day |
Selenium content of food is largely dependent on location and soil conditions, which vary widely.
Good natural food sources of selenium include:
- Nuts, like Brazil nuts and walnuts
- Many fresh and saltwater fish, like tuna, cod, red snapper, and herring
- Beef and poultry
- Grains
Whole foods are the best sources of selenium. The mineral may be destroyed during processing.
- Side effects. Taken at normal doses, selenium does not usually have side effects. An overdose of selenium may cause bad breath, fever, and nausea, as well as liver, kidney and heart problems and other symptoms. At high enough levels, selenium could cause death.
- Interactions. Selenium may also interact with other medicines and supplements, such as some antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statin drugs, and birth control pills.
- Skin cancer. Selenium supplements may be associated with a risk of skin cancer (squamous cell carcinoma), so people at high risk of skin cancer should not take these supplements.
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Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews
Overview
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 ?
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.
Moderate Interaction
Be cautious 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.
Minor Interaction
Be watchful with this combination
Dosing
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.
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.
Summary
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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References
Kieliszek, M.; Błażejak, S. Current knowledge on the importance of selenium in food for living organisms: A review. Molecules 2016, 21, 609.
Duntas, L. H.; Benvenga, S. Selenium: An element for life. Endocrine 2015, 48, 756–775.
Pedrero, Z.; Madrid, Y. Novel approaches for selenium speciation in foodstuffs and biological specimens: A review. Anal. Chim. Acta 2009, 634, 135–152.
Beck, M.A.; Levander, O.A.; Handy, J. Selenium deficiency and viral infection. J. Nutr. 2003, 133, 1463-1467.
Dennert G, Zwahlen M, Brinkman M, Vinceti M, Zeegers MP, Horneber M. Selenium for preventing cancer. Sao Paulo Medical Journal. 2012;130(1).
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).
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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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).
Sources:
- Botsiev T.O., Kubalova L.M. Biological role of selenium and its compounds // International Student Scientific Bulletin. – 2015. – No. 3-4.
- 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.
IMPORTANT!
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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