Supplement Forms/Alternate Names

Se, selenite, selenomethionine, selenized yeast, selenium dioxide


Selenium is a compound found in grains, meat, and nuts. The body uses selenium to make antioxidants that help fight damage to cells. Selenium has been used to improve thyroid and heart health. It has also been used to promote general wellness and help the body fight off illness. Selenium can be taken as a pill or tincture. It can also be injected into the bloodstream by a healthcare provider.


200 micrograms once daily

What Research Shows

Likely Effective

  • Metabolic syndrome—likely to improve insulin sensitivity; but unlikely to improve blood fat and blood glucose levels I1

May Be Effective

  • Critical illness —may lower mortality F1-F4

Unlikely to Be Effective

Not Enough Data to Assess

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to take selenium in small doses . Doses higher than 400 micrograms daily may not be safe. Women who are pregnant or breastfeeding should especially avoid excessive doses of selenium.


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse such as:

  • People with diabetes should talk to their doctors before taking selenium. It may worsen symptoms.


A. Asthma

A1. Allam MF, Lucane RA. Selenium supplementation for asthma. Cochrane Database Syst Rev. 2004;(2):CD003538.

B. Cancer Prevention

B1. Lee EH, Myung SK, et al. Effects of selenium supplements on cancer prevention: meta-analysis of randomized controlled trials. Nutr Cancer. 2011 Nov;63(8):1185-1195.

B2. Vinceti M, Filippini T, et al. Selenium for preventing cancer. Cochrane Database Syst Rev. 2018;1:CD005195.

C. Cardiovascular Disease

C1. Rees K, Hartley L, et al. Selenium supplementation for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2013;(1):CD009671.

D. Cognitive Function

D1. Rutjes AW, Denton DA, et al. Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life. Cochrane Database Syst Rev. 2018 Dec 17;12:CD011906.

E. Coronary Heart Disease

E1. Ju W, Li X, et al. Th effect of selenium supplementation on coronary heart disease: A systematic review and meta-analysis of randomized controlled trials. J Trace Elem Med Biol. 2017;44:8-16.

F. Critical Illness

F1. Huang TS, Shyu YC, et al. Effect of parenteral selenium supplementation in critically ill patients: a systematic review and meta-analysis. PLoS One. 2013;8(1):e54431.

F2. Landucci F, Mancinelli P, et al. Selenium supplementation in critically ill patients: a systematic review and meta-analysis. J Crit Care. 2014 Feb;29(1):150-156.

F3. Allingstrup M, Afshari A. Selenium supplementation for critically ill adults. Cochrane Database Syst Rev. 2015;(7):CD003703.

F4. Zhao Y, Yang M, et al. The clinical outcomes of selenium supplementation on critically ill patients: A meta-analysis of randomized controlled trials. Medicine (Baltimore). 2019 May;98(20):e15473.

G. HIV Infection

G1. Siegfried N, Irlam JH, et al. Micronutrient supplementation in pregnant women with HIV infection. Cochrane Database Syst Rev. 2012 Mar 14;(3):CD009755.

G2. Irlam JH, Siegfried N, et al. Micronutrient supplementation for children with HIV infection. Cochrane Database Syst Rev. 2013 Oct 11;(10):CD010666.

G3. Visser ME, Durao S, et al. Micronutrient supplementation in adults with HIV infection. Cochrane Database Syst Rev. 2017 May 18;5:CD003650.

H. Lipid Profile

H1. Hasani M, Djalalinia S, et al. Effect of Selenium Supplementation on Lipid Profile: A Systematic Review and Meta-Analysis. Horm Metab Res. 2018 Oct;50(10):715-727.

I. Metabolic Syndrome

I1. Tabrizi R, Akbari M, et al. The Effects of Selenium Supplementation on Glucose Metabolism and Lipid Profiles Among Patients with Metabolic Diseases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Horn Metab Res. 2017;49(11):826-830.

J. Sepsis

J1. Alhazzani W, Jacobi J, et al. The effect of selenium therapy on mortality in patients with sepsis syndrome: a systematic review and meta-analysis of randomized controlled trials. Crit Care Med. 2013;41(6):1555-1564.

J2. Kong Z, Wang F, et al. Selenium supplementation for sepsis: a meta-analysis of randomized controlled trials. Am J Emerg Med. 2013;31(8):1170-1175.

J3. Li S, Tang T, et al. A meta-analysis of randomized controlled trials: Efficacy of selenium treatment for sepsis. Medicine (Baltimore). 2019 Mar;98(9):e14733.

Last reviewed July 2019 by EBSCO NAT Review Board Eric Hurwitz, DC
Last Updated: 3/30/2020

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