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Selenium (Se)

Synonyms/Common Names/Related Substances:

  • 5-Methylselenocysteine, adrusen zinco, atomic number 34, DL-selenomethionine, ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), gamma-glutamyl-selenomethyl-SeCys, high-selenium yeast, L-selenomethionine, methylseleninic acid, methyl selenol, monomethylated Se, MSC, Na2SeO3, parselenium, Se, Se-EMP, selen, selenate, selenious acid, selenite, selenite-exchangeable metabolic pool, selenium, 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 (Semet), selenomethyl-SeCys, selenoprotein P, selenoproteins, selenous acid, Sele-Pak, selepen, Selmevit, Se-malt, SeMCYS, Seme, SeMet, Se-methylselenocysteine, SeO3(2-), SeO4(2-), SeS, se-spirulina, Se-yeast, se-yeast, SLM, sodium selenate, sodium selenite (Na2SeO3), Spirulin-Sochi-Selen, wheat selenium.
  • Selected combination products: Selmevit.

Clinical Bottom Line/Effectiveness

Brief Background:

  • Selenium (Se) is an essential trace mineral (1;2) found in soil, water, and some foods. In humans, selenium functions as a cofactor for the antioxidant enzymes, including glutathione peroxidase, whose main role is to protect organisms from oxidative damage, and some thioredoxin reductases, which are essential for cell growth and survival. Selenium supplements contain selenium in different chemical forms. In the majority of supplements, selenium is present as selenomethionine or selenocysteine. Selenomethionine, which cannot be synthesized by humans and is initially synthesized in plants, is incorporated randomly in place of methionine in a variety of proteins obtained from plant and animal sources. However, in multivitamin preparations, infant formulas, protein mixes, weight loss products and animal feed, sodium selenite and sodium selenate are predominantly used (3).
  • Initial evidence from the Nutritional Prevention of Cancer (NPC) trial suggests that selenium supplementation reduces the risk of prostate cancer among men with normal baseline PSA (prostate specific antigen) levels and low selenium blood levels (4). 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 (4;5;6;7). The ongoing Selenium and Vitamin E Cancer Prevention Trial (SELECT) aims to address definitively the role of selenium in prostate cancer prevention (8). Initial analyses of this study have been released, and it appears as though 200mcg of selenium and 400 IU of vitamin E daily does not prevent prostate cancer, and investigators from the study leadership have suggested that participants in the trial stop taking their study supplements.
  • Epidemiological data suggest an association between low selenium levels in humans and the risk of cardiomyopathy, cardiovascular disease, and cancer (9). Selenium levels have been noted to be lower in HIV-positive patients with cardiomyopathy (10;11), and selenium has been studied as a potential treatment for HIV (12;13;14).
  • Selenium has been shown to exert a strong protective action against the poisoning effects of many heavy metals (15), some organic toxicants (16), and mycotoxins (17;18).

Dosing/Toxicology

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Precautions/Contraindications

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Interactions

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.

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Mechanism of Action

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History

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Evidence Table

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Evidence Discussion

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Products Studied

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Author Information

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References

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 www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.