INDEX

Selenium

Background

  • Selenium is an essential trace mineral found in soil, water, and some foods. 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.

Scientific Evidence

Uses Grade*
Antioxidant

Selenium is a component of the enzyme glutathione peroxidase, which has antioxidant properties in humans. Further research is needed.

B
Keshan disease

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.

B
Prostate cancer prevention

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.

B
Amyotrophic lateral sclerosis (ALS)

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.

C
Asthma

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.

C
Blood disorders

Selenium supplementation lacked benefit in patients with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency. Selenium supplementation may also affect platelet function and blood clotting.

C
Cancer prevention

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.

C
Cancer treatment

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.

C
Cardiovascular disease (prevention)

Studies of the effects of selenium intake and supplementation on cardiovascular disease yield inconsistent findings. Better-designed trials are needed before a conclusion can be made.

C
Chemotherapy side effects

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.

C
Colitis (inflammation of the large intestine)

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.

C
Critical illness

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.

C
Cystic fibrosis

Preliminary research on the effect of selenium supplementation in cystic fibrosis patients yields indeterminate results. Further research is needed in this area.

C
Dandruff

Selenium sulfide may help improve dandruff. Selenium is included in some commercially available shampoos. More research is needed.

C
Dialysis

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.

C
Eye disorders

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.

C
Fatigue (associated with primary biliary cirrhosis)

Antioxidant supplementation, including selenium, has been studied for treating fatigue associated with biliary cirrhosis. Evidence of benefit is inconclusive. More research is needed.

C
Heavy metal/lead toxicity

Zinc and selenium have been shown to exert protective effects against mercury toxicity. More research is needed before a conclusion can be drawn.

C
High blood pressure

Some studies have reported a possible relationship between low serum selenium levels and increased blood pressure. Additional study is needed in this area.

C
HIV/AIDS

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.

C
Immune stimulation

Selenium may help prevent infection by stimulating immune function. Further research is needed before a conclusion can be made.

C
Infection prevention

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.

C
Infertility

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.

C
Intracranial pressure symptoms

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.

C
Liver disease

Selenium supplementation has been studied in various liver disorders, including hepatitis, cirrhosis, and liver cancer, with mixed results. More study is needed.

C
Longevity/anti-aging

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.

C
Low birth weight

Selenium supplementation has been studied in low birth weight infants. Additional study is needed before a clear conclusion can be drawn.

C
Malabsorption

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.

C
Nutritional support

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.

C
Pancreatitis

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.

C
Physical endurance

Available evidence suggests that selenium supplementation lacks effect on physical performance or endurance training. Additional studies are needed.

C
Post-operative recovery

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.

C
Pregnancy-related complications

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.

C
Quality of life

Studies of selenium supplementation for mood elevation and quality of life yield mixed results. Further research is needed before a firm conclusion may be reached.

C
Radiation side effects

Selenium supplementation has been used as an adjunct therapy to treat radiation side effects. Additional research is necessary before a clear conclusion can be made.

C
Respiratory tract infections

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.

C
Rheumatoid arthritis

Selenium supplementation has been studied in rheumatoid arthritis patients with mixed results. Additional research is necessary before a clear conclusion can be made.

C
Seizures

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.

C
Sepsis (severe bacterial infection of the blood)

Study results of selenium supplementation in septic patients are mixed. Research using selenium alone is needed.

C
Sunburn prevention

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.

C
Thyroid conditions

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.

C
Yeast infections

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.

C
Diabetes (prevention)

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.

D
Kashin-beck osteoarthropathy

Kashin-Beck disease is an osteoarthropathy common in selenium- and iodine-deficient areas. Preliminary evidence suggests that selenium supplementation lacks effectiveness.

D
Muscle and joint disorders

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.

D
Osteoarthritis

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.

D
Skin cancer (nonmelanoma) prevention

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.

D
Skin disorders

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.

D

*Key to grades:

A: Strong scientific evidence for this use;

B: Good scientific evidence for this use;

C: Unclear scientific evidence for this use;

D: Fair scientific evidence against this use (it may not work);

F: Strong scientific evidence against this use (it likely does not work).

Tradition

  • Abnormal pap smears, acne, alcoholism, altitude sickness, Alzheimer’s disease, arsenic poisoning, atherosclerosis (hardening of the arteries), benign prostatic hypertrophy (BPH), bone density, burns, cardiac arrhythmia (irregular heartbeat), celiac disease, cognitive disorders, cosmetic uses, Crohn’s disease, depression, diabetic retinopathy, diarrhea, detoxification from alcohol or toxins, Down’s Syndrome, ear infections, eczema, endocrine disorders, epilepsy, fetal development, Graves’ disease, growth disorders (growing pains), hay fever, heart attack treatment/prevention/rehabilitation, hyperglycemia (high blood sugar), hyperlipidemia (high blood lipids), infant eye/brain development, inflammation, inflammatory bowel disease, lung disease, lupus erythematosus, lymphedema, menopausal symptoms, metabolic enhancement, miscarriage prevention, mood disorders, multiple organ failure, multiple sclerosis (MS), muscle weakness, neonatal disorders, non-Hodgkin’s lymphoma, pain, parasites and worms, partial androgen deficiency, phenylketonuria, pneumonia, poison prophylaxis, radioprotection, Raynaud’s phenomenon, sinusitis, skin aging, sleep apnea, stroke, sudden infant death syndrome (SIDS), systemic sclerosis, tuberculosis, vaccine adjunct, vasculitis, weight loss, wound healing.

Dosing

Adults (over 18 years old)

  • The U.S. recommended dietary allowance (RDA) taken by mouth for adults is: 55 micrograms for males and females; 60 micrograms for pregnant females; and 70 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) taken by mouth for infants and children is 15 micrograms daily for 0-6 months of age; 20 micrograms daily for 6-12 months of age; 20 micrograms for 1-3 years of age; 30 micrograms for 4-8 years of age; 40 micrograms for 9-13 years of age; and 55 micrograms for 14-18 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.

References

  1. 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
  2. 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
  3. 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
  4. 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
  5. Etminan M, FitzGerald JM, Gleave M, et al. Intake of selenium in the prevention of prostate cancer: a systematic review and meta-analysis. Cancer Causes Control 2005;(9):1125-31. View Abstract
  6. Hurwitz BE, Klaus JR, Llabre MM, et al. Suppression of human immunodeficiency virus type 1 viral load with selenium supplementation: a randomized controlled trial. Arch Intern Med. 2007 Jan 22;167(2):148-54. View Abstract
  7. Lippman SM, Klein EA, Goodman, P. J., et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). 2009;301(1):39-51. View Abstract
  8. Rayman M, Thompson A, Warren-Perry M, et al. Impact of selenium on mood and quality of life: a randomized, controlled trial. Biol Psychiatry 2006;59(2):147-54. View Abstract
  9. Reid ME, Duffield-Lillico AJ, Slate E, et al. The nutritional prevention of cancer: 400 mcg per day selenium treatment. Nutr Cancer 2008;60(2):155-163. View Abstract
  10. Reid ME, Duffield-Lillico AJ, Sunga A, et al. Selenium supplementation and colorectal adenomas: an analysis of the nutritional prevention of cancer trial. Int J Cancer 2006 Apr 1;118(7):1777-81. View Abstract
  11. Shaheen SO, Newson RB, Rayman MP, et al. Randomised, double blind, placebo-controlled trial of selenium supplementation in adult asthma. Thorax 2007;62(6):483-90. View Abstract
  12. Stawicki SP, Lyons M, Aloupis M, et al. Current evidence from phase III clinical trials of selenium supplementation in critically Ill patients: why should we bother? Mini Rev Med Chem 2007;7(7):693-9. View Abstract
  13. Stranges S, Marshall JR, Natarajan R, et al. Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial. Ann Intern Med 2007;21;147(4):217-23. View Abstract
  14. Stranges S, Marshall JR, Trevisan M, et al. Effects of selenium supplementation on cardiovascular disease incidence and mortality: secondary analyses in a randomized clinical trial. Am J Epidemiol 2006;163(8):694-9. View Abstract
  15. 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