- 5-methylselenocysteine MSC, adrusen zinco, atomic number 34, DL-selenomethionine, benzisoselenazol, ebselen, gamma-glutamyl-selenomethyl-SeCys, high-selenium yeast, L-selenomethionine, methylseleninic acid, methyl selenol, monomethylated Se, Na2SeO3, parselenium, Se, Se-EMP, Sele-Pak, selepen, Se-malt, SeMCYS, Seme, SeMet, Se-methylselenocysteine, SeO3(2-), SeO4(2-), SeS, Se-yeast, selen, selenium dioxide, selenium sulfide, seleno yeast, selenocysteine, selenomethionine, selenate, selenious acid, selenite, selenite-exchangeable metabolic pool, selenium dioxide, selenium disulfide, selenium sulfide, selenium-enriched wheat, selenium-enriched yeast, selenium-rich pea flour, selenium-zinc, selenized yeast, seleno yeast, selenocysteine, selenoenzymes, seleno-L-methionine, selenomethionine, selenomethyl-SeCys, selenoprotein P, selenoproteins, selenous acid, selepen, Selmevit, Semet, se-spirulina, se-yeast, SLM, sodium selenate, sodium selenite, Spirulin-Sochi-Selen, wheat selenium.
- Selenium is an essential trace mineral found in soil, water, and some foods. It is a component of the amino acids cysteine and methionine. Selenium is required for functioning of the body’s antioxidant enzymes and for cell growth and survival.
- The presence of selenium in locally grown food and selenium levels in human populations reflects the selenium levels in local soil. The selenium content in food is influenced by geographical location, seasonal changes, protein content, and food processing. Periodic monitoring of selenium levels in soil and food is necessary. Selenium supplements may benefit people living in regions with very low environmental levels of selenium.
- Selenium has a strong protective action against the poisonous effects of many heavy metals, some toxic compounds, and fungal toxins.
- The role of selenium in cancer prevention has been the subject of recent study and debate. Initial evidence from the Nutritional Prevention of Cancer (NPC) trial suggested that selenium supplementation reduced the risk of prostate cancer among men with normal baseline PSA (prostate specific antigen) levels and low selenium blood levels. However, in this study, selenium did not reduce the risk of lung, colorectal, or basal cell carcinoma of the skin and actually increased the risk of squamous cell skin carcinoma.
– Keshan disease affects heart muscle in people with extremely low selenium status. Preventative administration of sodium selenite, a form of selenium, was shown to reverse heart failure due to selenium deficiency. Although initial results are promising, more high quality studies are needed.
– Initial evidence suggested that selenium supplementation may reduce the risk of developing prostate cancer in men with normal baseline PSA (prostate specific antigen) levels and low selenium blood levels. Additional study showed an apparent lack of benefit, however. Further research is required before firm conclusions can be made.
– Studies have consistently reported that antioxidants lack benefit in treating motor neuron diseases such as amyotrophic lateral sclerosis (ALS). High quality research is needed before firm conclusions can be made.
– Preliminary research suggests that selenium supplementation, alone or in combination with other vitamins and minerals, may help reduce asthma symptoms. Further research is needed before a conclusion can be made.
– Initial study suggests that low body levels of selenium may be a risk factor for developing cancer, particularly gastrointestinal, gynecological, lung, colorectal, and esophageal cancer. Studies have shown significantly reduced risk of some (but not all) cancers in people taking selenium supplements. Additional research is needed to determine the precise role of selenium in reducing cancer risk.
– Preliminary study suggests that low body levels of selenium may be a risk factor for developing cancer, particularly prostate, gastrointestinal, gynecological, and colorectal cancer. Population studies reported that people with cancer are more likely to have low selenium levels than healthy individuals, but in most cases it is not clear if the low selenium levels are a cause or an effect of the cancer. It remains unclear if selenium is beneficial for treating any type of cancer.
– Study results of selenium supplementation (usually in combination with other nutrients) during chemotherapy are mixed. Antioxidants may interfere with radiation therapy or some chemotherapy agents, which themselves may depend on oxidative damage to tumor cells for their anti-cancer activity. Further research is needed before a conclusion can be made.
– Selenium in combination with fish oil, fructooligosaccharides, gum arabic, vitamin E, and vitamin C has shown some benefit in reducing inflammation associated with ulcerative colitis. Studies testing selenium alone are needed before a conclusion can be made.
– Limited study has tested the effect of selenium on improving health or decreasing mortality in critically ill patients. Results are inconsistent. More research is required before firm conclusions can be made.
– The benefits of selenium supplementation in dialysis patients remain unclear. Some methods of dialysis may lower plasma selenium levels. More well-designed trials are needed before a conclusion can be made.
– Although people with relatively high dietary intake of selenium have reduced risk of certain eye disorders, the effect of selenium supplements on the risk of developing these disorders is unknown. More research in this area is needed.
– Some reports associate low selenium levels in HIV/AIDS patients with complications such as cardiomyopathy. It remains unclear if selenium supplementation is beneficial in patients with HIV, particularly during antiretroviral therapy.
– Preliminary research reports that selenium may reduce recurrence of some bacterial infections of the skin or blood, or bacterial pneumonia. Selenium may help prevent infection by stimulating immune function. Further research is needed before a conclusion can be made.
– Selenium supplementation has been studied for male infertility and sperm motility with mixed results. Evidence is lacking regarding the potential effects on female infertility. Additional study is needed.
– Preliminary research shows a decrease in symptoms of elevated intracranial pressure (headaches, nausea, vomiting, vertigo, unsteady gait, speech disorders, and seizures) with selenium supplementation together with other therapies. More research on the effect of selenium alone is needed before a conclusion can be made.
– Because antioxidant supplements are thought to slow aging and prevent disease, it has been proposed that selenium supplementation may help people live longer. However, results from clinical trials are mixed, and it is still unclear whether selenium supplementation can increase lifespan in healthy individuals.
– Low selenium status has been demonstrated in several malabsorptive syndromes and in some digestive and gastrointestinal allergic conditions. There is some evidence that children with food allergies have a higher risk of selenium deficiency. Further research is needed in this area.
– Selenium supplementation has been shown to be effective in increasing and maintaining selenium levels in various populations, including breastfeeding mothers and patients with advanced kidney disease. Additional studies are needed before a conclusion can be made.
– Selenium together with probiotics and prebiotics may help patients with acute pancreatitis. There is inconclusive evidence regarding the use of selenium alone in pancreatitis. More research is needed.
– In limited study, selenium aided postoperative recovery and reduced swelling after surgery. Patients with severe inflammation resulting from surgeries or extensive burns may benefit from selenium therapy. More studies are needed to determine whether selenium is a suitable addition to post-operative therapy and care.
– Preliminary study in women with pregnancy-induced high blood pressure reported reduced swelling with selenium supplementation, without a significant impact on birth outcomes. Additional well-designed research is needed.
– Some evidence indicates that selenium may promote recovery from bronchitis and pneumonia caused by respiratory syncytial virus (RSV). Though supplemental selenium may correct selenium deficiency in patients with bronchitis, more studies are needed to examine its effectiveness in treating respiratory infections.
– It is unclear whether serum selenium levels are related to seizures in patients with epilepsy or brain tumors. More research is needed to examine whether selenium supplementation may affect the frequency or severity of seizures.
– Sun protection was initially observed in preliminary research using selenium supplementation and other antioxidants, although there is some evidence of ineffectiveness in preventing light-induced skin redness. More studies are needed.
– Thyroid function is thought to depend on selenium, and thyroid problems are common in patients with selenium deficiency. Selenium has been suggested to improve goiter, as well as inflammatory activity in chronic autoimmune thyroiditis or Grave’s disease. Further research is needed.
– Commercially available 1% selenium sulfide shampoo has been reported as equivalent to antifungal therapy for treatment of several types of fungal infections. Further high quality evidence is needed.
– Some studies have suggested that selenium supplementation may help prevent type 2 diabetes by improving glucose metabolism. However, other data showed increased rates of type 2 diabetes in people taking selenium supplements. These results indicate a potential risk of selenium supplementation that needs further examination.
– Selenium and vitamin supplementation has been studied in patients with Duchenne muscular dystrophy (DMD), myotonic dystrophy, and exercise-induced muscle injury. However, selenium does not appear to improve muscle strength or motor performance in patients with myotonic dystrophy. Despite promising early evidence, selenium supplementation does not appear to affect muscle strength or disease progression in muscular dystrophy.
– Selenium-ACE, a formulation containing selenium with three vitamins, has been promoted for the treatment of arthritis. Research has failed to demonstrate significant benefits and there may be more side effects compared to placebo.
– Results of a large study suggested that selenium supplementation given to individuals at high risk of nonmelanoma skin cancer is ineffective at preventing basal cell carcinoma and actually increases the risk of squamous cell carcinoma and nonmelanoma skin cancer. Therefore, selenium supplementation should be avoided in individuals at risk or with a history of nonmelanoma skin cancer.
– Taking selenium by mouth has been studied for its effects on psoriasis and lesions induced by arsenic. Selenium has also been used to treat eczema, to increase the rate of burn wound healing, and may be effective for the treatment of dermatitis herpetiformis. Currently available results fail to support a role for selenium in treating these various skin disorders.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
*Key to grades:
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
Adults (over 18 years old)
- The U.S. recommended dietary allowance (RDA) for adults is 80-200 micrograms taken by mouth. Specifically: 55 micrograms for female adults; 70 micrograms for male adults; 40-70 micrograms for adolescent males, 45-55 micrograms for adolescent females; 65 micrograms for pregnant females; and 75 micrograms for breastfeeding females.
- Selenium availability in the body varies according to the selenium source and nutritional status of the person, and is significantly higher for organic forms of selenium.
- For asthma, 100 micrograms of sodium selenite has been taken by mouth daily for 14 weeks.
- For cancer prevention, 200 micrograms of selenium has been taken by mouth daily.
- For cardiovascular disease (prevention), 100 micrograms of selenium-rich yeast has been taken by mouth daily for six months.
- For critical illness, 500 micrograms of selenium has been taken by mouth during the first five days after injury.
- For dandruff, 1% and 2.5% selenium sulfide shampoo have been used twice weekly for the first two weeks, then once weekly for weeks two, three, and four.
- For heavy metal / lead toxicity, 100 micrograms of selenomethionine has been taken by mouth.
- For immune stimulation, 100 micrograms of selenium (as sodium selenite) has been taken by mouth daily for 15 weeks.
- For infertility (male), 200 micrograms of selenium has been taken by mouth daily for 26 weeks.
- For liver disease, 100 micrograms of selenium as enriched yeast has been taken by mouth daily for four months.
- For nutritional support, 28 micrograms of selenite or selenate has been taken by mouth for 14 days in patients on hemodialysis. In breastfeeding women, 100 micrograms of yeast selenite has been taken by mouth daily.
- For pancreatitis, 500 micrograms of sodium selenite has been taken by mouth daily.
- For physical endurance, 240 micrograms of organic selenium has been taken by mouth three times weekly for 10 weeks.
- For pregnancy-related complications, 100 micrograms of selenium dietetic liquid has been taken by mouth daily for 6-8 weeks during late pregnancy.
- For quality of life, 100 micrograms of selenium has been taken by mouth daily for five weeks. In HIV-positive drug users, 200 micrograms of selenium has been taken by mouth.
- For rheumatoid arthritis, 200 micrograms of sodium-selenite has been taken by mouth daily for three months.
- For sepsis, 474 micrograms, 316 micrograms, and 158 micrograms of selenium has been taken by mouth daily. For sepsis in critically ill patients, 1,000 micrograms of sodium-selenite has been delivered intravenously, within 30 minutes of admission, followed by 1,000 micrograms of sodium-selenite during 24 hours continuously for 14 days, for a total of 15 milligrams of selenium within 14 days.
- For selenium deficiency in adults, 100 micrograms of elemental selenium has been delivered parenterally daily for 24-31 days. For prevention of selenium deficiency in adults, 20-40 micrograms of elemental selenium daily has been suggested.
- For skin infections, the following treatment has been used daily for seven days: 1% and 2.5% selenium lotion have been applied to the affected area, left on the skin for 10 minutes, and then rinsed.
- For thyroid conditions, 200 micrograms of sodium selenite has been taken by mouth daily for three months to one year.
Children (under 18 years old)
- The U.S. Recommended Dietary Allowance (RDA) for infants and children is 10 micrograms taken by mouth daily for 0-6 months of age; 15 micrograms daily for 6-12 months of age; 20 micrograms for 1-6 years of age; 30 micrograms for 7-10 years of age; 45 micrograms for 11-14 years of age; and 50 micrograms for 5-18 years of age. Adequate intake for infants up to six months old may be 2.1 micrograms per kilogram of body weight taken by mouth daily and for infants 7-12 months it may be 2.2 micrograms per kilogram of body weight taken by mouth daily.
- The recommended maximum daily dose taken by mouth is 45 micrograms for 0-6 months of age; 60 micrograms for 7-12 months of age; 90 micrograms for 1-3 years of age; 150 micrograms for 4-8 years of age; and 280 micrograms for 9-13 years of age.
- For selenium deficiency in premature infants, 5 micrograms of selenized yeast has been given by a nasogastric tube daily. Doses taken by mouth are: infants 0-6 months of age, 10 micrograms daily; infants 6-12 months of age, 15 micrograms daily; children 1-6 years of age, 20 micrograms daily; children 7-10 years of age, 30 micrograms daily; males 11-14 years of age, 40 micrograms daily; males 15-18 years of age, 40 micrograms daily. For selenium deficiency or prevention, 42 micrograms of elemental selenium as H2SeO3 has been delivered intravenously daily.
- For cystic fibrosis in children, 2.8 micrograms of sodium selenite per kilogram of body weight has been taken by mouth daily for five months.
- For low birth weight in preterm infants, 4.8 milligrams of yeast containing 5 micrograms of selenium delivered by naso-gastric drip has been given daily during the first 14 postnatal days.
- For respiratory tract infections in children hospitalized with pneumonia or bronchiolitis caused by respiratory synctial virus (RSV), 1 milligram of sodium selenite has been given by mouth on the second day of hospitalization.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
- Selenium is a trace element and hypersensitivity is unlikely. Avoid with known allergy or hypersensitivity to products containing selenium.
Side Effects and Warnings
- Chronic exposure and high intake of selenium have produced adverse effects, including death. Chronic exposure to organic and inorganic selenium may cause neurotoxicity, particularly motor neuron degeneration leading to an increased risk of amyotrophic lateral sclerosis (ALS). Nausea, vomiting, and liver dysfunction have been reported as a result of high selenium exposure. Excessive amounts of selenium may cause hair and nail loss, dermatitis, impaired endocrine function and neurotoxicity, selenosis (affects the liver, skin, nails, and hair), and dermatitis. Excessive selenium intake has also been associated with garlic odor on breath and a metallic taste.
- Selenium may reduce serum levels of somatotropin (growth hormone) and insulin-like growth factor-1 (IGF-1), followed by growth retardation. Hypothyroidism, secondary to iodine deficiency, has been reported as a result of selenium intravenous administration. Selenium supplementation may reduce sperm motility.
- Use cautiously at doses from 27-2,310 milligrams daily.
- Use cautiously in patients on hemodialysis, as erythropoietin (EPO) and selenium taken together may increase selenium levels in these patients.
- Use cautiously in patients with iodine deficiency, as hypothyroidism has been reported as a result of selenium supplementation.
- Use cautiously in patients with high cholesterol, as high serum selenium concentrations have been associated with increased total and LDL cholesterol.
- Use cautiously in patients with immune disorders or those using immunosuppressants, as selenium has been shown to stimulate the immune system.
- Use cautiously in patients using corticosteroids, as these agents may lower selenium levels.
- Use cautiously in patient using antacids, as these agents may reduce the absorption of selenium.
- Use cautiously in patients using erythropoietin (EPO), as selenium may increase the effects of EPO.
- Use cautiously in patients using HMG-CoA reductase inhibitors (“statins”), as selenium may reduce the effectiveness of these agents.
- Use cautiously in patients using oral contraceptives, as these agents may reduce selenium levels.
- Use cautiously in patients using astragalus, as this herb may cause selenium to accumulate in the body.
- Use cautiously in patients taking iron supplements, as selenium levels may be affected by iron supplementation.
- Avoid in patients at high risk of nonmelanoma skin cancer, as selenium supplementation has been shown to increase the risk of squamous cell carcinoma and nonmelanoma skin cancer.
- Avoid in patients at risk for developing diabetes, as selenium supplementation may increase risk for type 2 diabetes.
- Avoid in patients with known allergy/hypersensitivity to products containing selenium; however, selenium is a trace element, and hypersensitivity is unlikely.
Pregnancy and Breastfeeding
- The U.S. recommended dietary allowance (RDA) of selenium for adults is 65 micrograms for pregnant females and 75 micrograms for breast-feeding females.
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.
Interactions with Drugs
- Selenium may interact with anticoagulants and antiplatelets. However, available research results are conflicting.
- Selenium may affect blood sugar levels. Caution is advised when using drugs that may also affect blood sugar. Patients taking drugs for diabetes by mouth or injection should be monitored closely by a qualified healthcare professional. Dosing adjustments may be necessary.
- Selenium may also interact with anticancer agents, anti-inflammatory agents, barbiturates, cholesterol-lowering drugs, cisplatin, clozapine, corticosteroids, erythropoietin (EPO), estrogens, gastric acid-reducing agents, antiulcer agents, growth hormones, agents that affect the immune system, iron salts, thyroid hormones, or valproic acid.
Interactions with Herbs and Dietary Supplements
- Selenium may interact with anticoagulants and antiplatelets. However, available research results are conflicting.
- Selenium may affect blood sugar levels. Caution is advised when using herbs and supplements that may also affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
- Selenium may also interact with anti-cancer herbs and supplements, anti-inflammatory herbs and supplements, cholesterol-lowering herbs and supplements, antioxidants, astragalus, calcium, chromium, coenzyme Q10, diets high in refined foods, fish, fortified eggs (enriched with vitamin E, lutein, Se, and DHA), garlic, gastric acid reducing herbs and supplements, antiulcer herbs and supplements, herbs and supplements that affect the immune system, ketogenic diet, iodine, iron, omega-3 fatty acids, phytoestrogens, vitamin C, zinc, and a vegetarian diet.
- This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration ().
Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to . Selected references are listed below.
- Arnaud J, Arnault N, Roussel AM, et al. Relationships between selenium, lipids, iron status and hormonal therapy in women of the SU.VI.M.AX cohort. J Trace Elem Med Biol 2007;21 Suppl 1:66-9. View Abstract
- Bardia A, Tleyjeh IM, Cerhan JR, et al. Efficacy of antioxidant supplementation in reducing primary cancer incidence and mortality: systematic review and meta-analysis. Mayo Clin Proc 2008;83(1):23-34. View Abstract
- Bjelakovic G, Nikolova D, Gluud L., et al. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev 2008;(2):CD007176. View Abstract
- Duffield-Lillico AJ, Slate EH, Reid ME, et al. Selenium supplementation and secondary prevention of nonmelanoma skin cancer in a randomized trial. J Natl Cancer Inst 2003;95(19):1477-1481. View Abstract
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- You WC, Brown LM, Zhang L, et al. Randomized double-blind factorial trial of three treatments to reduce the prevalence of precancerous gastric lesions. J Natl Cancer Inst 2006;98(14):974-83. View Abstract