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Selenium is an essential nutrient for many species, including humans. Deficiencies of this element are very apparent in animals, with symptoms ranging from muscular dystrophy in lambs, to the destruction of liver tissue in pigs.

Selenium is an important constituent of the enzyme glutathione peroxidase, which is responsible for destroying lipid-damaging peroxides. In this role, selenium complements the antioxidizing function of vitamin E.

The enzyme glutathione peroxidase is contained within white blood cells and blood platelets, and has importance in the immune system and blood clotting mechanisms of the body.

Selenium may also be important in the regulation of serum cholesterol levels, although this effect has not been conclusively proven experimentally.

Selenium serves to prevent the incidence of mercury poisoning by affecting the body's metabolism of the potential toxin.

Method of Action

Selenium is an important constituent of the enzyme glutathione peroxidase. This enzyme acts to destroy peroxides, thereby protecting cells and membranes against oxidative damage. Vitamin E and selenium tend to enhance the effect of one another in that vitamin E works to prevent the formation of peroxides, and glutathione peroxidase destroy what is already formed.

Glutathione peroxidase is also a constituent of blood platelets and white blood cells, making it an important part of the body's immune response system and blood clotting mechanism.

Absorption of selenium is dependent upon the solubility of the ingested compound and upon dietary ratio of selenium to sulfur. The availability of selenium for absorption is dependent upon many different factors, among which are the nature of the food source (i.e., seafood is high in selenium, but the selenium is poorly absorbed) and the method of food processing.

Once absorbed, selenium interacts with the sulfur-containing amino acids (e.g., cysteine and methionine) to form the enzyme glutathione peroxidase, and for incorporation into various proteins, such as hemoglobin and myoglobin.

Excesses of selenium are secreted in the urine, and the selenium-containing molecule dimethyl selenide is excreted during respiration. This molecule gives breath a garlicky odor characteristic of selenium toxicity.

Properties & Uses

Selenium supplementation has been useful in the treatment of a certain congestive heart disease found primarily in Chinese children. Selenium has also been used to eliminate skeletal muscle pain in some people. Selenium, in conjunction with vitamin E, may be useful in the prevention of heart disease.

Selenium supplements have been used in the treatment of anemia and growth problems which would not respond to other kinds of treatment.

Selenium moderates the symptoms of mercury toxicity and may be useful in instances of subacute mercury poisoning.

Adequate selenium intake has been statistically linked to a lower incidence of cancer mortality, but the conclusive evidence regarding selenium's relation to cancer development is not available.

Consequence of Deficiency

Selenium deficiency has not been conclusively linked to any specific set of symptoms in humans, although monkeys and other animals have serious physiological manifestations of deficiency. Symptoms in animals include muscle pain, red blood cell fragility, pancreas degeneration, growth retardation, and cataract formation. The link between animal and human symptoms of deficiency have not been concretely established.

As a side note, children with kwashiorkor have unusually low selenium stores and, therefore, selenium deficiency may occur concomitantly with abnormal protein metabolism.

Selenium deficiencies have been statistically linked to a higher incidence of cancer mortality, but the conclusivity of this relationship has not been settled.

Deficiencies of selenium may contribute to the excessive buildup of fats and other lipids in the liver, producing fatty liver syndrome.

Toxicity Factors

Selenium toxicity is most frequently seen in livestock grazing in regions of the Midwest where plants contain unusually high amounts of the element.

Human toxicity has not been conclusively determined but is considered to occur only as a result of high industrial exposure. Reported symptoms of toxicity include hair loss, depigmentation of skin, abnormal nails, and weariness. A garlicky odor on the breath, without garlic ingestion, may be an indication of selenium toxicity.

Recommended Dietary Allowance

ageRDA (mcg)RNI (mcg)
0-3 months 10 10
4-6 months 10 13
6-12 months 15 10
1-3 years 20 15
4-6 years 20 20
7-10 years 30 30
11-14 years 45 45
15-18 years 50 70
19+ years 70 75
11-14 years 45 45
15-18 years 50 60
19+ years 55 60
pregnancy 65 -
lactation 75 75

For over thirty years, Recommended Daily Amounts has existed in the United Kingdom. It has been used to measure the adequacy of an individual's diet. However, in 1991 the Committee on Medical Aspects of Food Policy (COMA) gave forth a whole new set of figures upon the request of the Department of Health's Chief Medical Officer. Reference Nutrient Intake (RNI) is one of these sets collectively known as "Dietary Reference Values." RNI is an amount of a nutrient that is enough for almost every individuals, even someone who has high needs for the nutrient. This level of intake is, therefore, considerably higher than what most people would need. If individuals are consuming the RNI of a nutrient they are most unlikely to be deficient in that nutrient.

Food Sources

BeefBeef kidney
Beef liverBrewer's yeast
Brown riceCereals
Chicken liverEgg
Lamb liverMilk
Pumpkin seedTurkey liver
Veal liverWhole wheat bread


References A - L

Allavena-C et al: Relationship of trace element, immunological markers, and HIV1 infection progression. Biol-Trace-Elem-Res. 1995 Jan-Mar; 47(1-3): 133-8.

Ames, B. N.: Carcinogens and Anticarcinogens . Mutagens in our Environment (1982); 3-19.

Ames, B. N.: Dietary carcinogens and anticarcinogens, oxygen radicals and degenerative diseases. Science, Vol. 221 (Sept. 1983); 1256-64.

Amodio-Cocchieri-R et al: Evaluation of the selenium content of the traditional Italian diet. Int-J-Food-Sci-Nutr. 1995 May; 46(2): 149-54.

Anonymous: Incorporation of selenium into glutathionc peroxidase. Nutrition Reviews, Vol. 45, No. I 1 (1987).

Anonymous: Does tissue glutathione level indicate organ senescence? Nutrition Reviews, Vol. 47, No. 10 (1989); 330-2.

Anonymous: Rheumatoid Arthritis and Selenium. Nutrition Review, Vol. 46, No. 8 (1988); 284-86.

Bekstein, M. and Whanger, P. Metabolism of Selenomethionine, and Effects of Interacting Compounds by Mammalian Cells in Culture. Journal of Inorganic Biochemistry, Vol. 29 (1987); 137-52.

Bonomini-M & Albertazzi-A: Selenium in uremia. Artif-Organs. 1995, 19(5): 443-8.

Borglund, M et al: Distribution of Selenium and Glutathione Peroxidase in Plasma Compared in Healthy Subjects and Rheumatoid Arthritis Patients. Scand J Clin Invest, Vol. 48 (1988); 27-32.

Bruggemann-J & Kumpulainen-J: The status of trace elements in staple foods. II. Some effects of cereal and potato processing. Z-Lebensm-Unters-Forsch. 1995 Jul; 201(1): 7-11.

Caillie-Bertrand, M. et al: Influence of Age on the Selenium Status in Belgium and the Netherlands. Pediatric Research, Vol. 20, No. 6 (1986); 574-6.

Calomme-M et al: Effects of selenium supplementation on thyroid hormone metabolism in phenylketonuria subjects on a phenylalanine restricted diet. Biol-Trace-Elem-Res. 1995 Jan-Mar; 47(1-3): 349-53.

Chang-JC et al: Selenium content of Brazil nuts from two geographic locations in Brazil.. Chemosphere. 1995 Feb; 30(4): 801-2.

Clark, L.C. Fed Proc., 1985; 44: 2584-2589.

Clark-LC & Alberts-DS: Selenium and cancer: risk or protection? [editorial; comment]. J-Natl-Cancer-Inst. 1995 Apr 5; 87(7): 473-5.

Constans-J et al: Serum selenium predicts outcome in HIV infection [letter]. J-Acquir-Immune-Defic-Syndr-Hum-Retrovirol. 1995 Nov 1; 10(3): 392.

Czanarin, Doris, M. 1984. Minerals - Food, Nutrition and Diet Therapy. M.V. Krause and L.K. Mahan. W.B. Saunders Co, Phila.

Darlow-BA: Selenium status of New Zealand infants fed either a selenium supplemented or a standard formula. J Paed-Child-Health. 1995 Aug; 31(4): 339-44.
Darlow-BA et al: The relationship of selenium status to respiratory outcome in the very low birth weight infant. Pediatrics. 1995 Aug; 96(2 Pt 1): 314-9.

D'Ilio, C., et al. Selenium level and glutathione-dep&ndent enzyme activities in normal and neolplastic human lung tissues. Carcinogenesis, Vol. 8, No. 2 (1987); 281-4.

Di-Ilio-C et al: Glutathione peroxidase and glutathione reductase activities in cancerous and non-cancerous human kidney tissues. Cancer-Lett. 1995 May 4; 91(1): 19-23.

Eastman-P: "Phytamins" are not ready for public consumption [news]
J-Natl-Cancer-Inst. 1995 Oct 4; 87(19): 1430-2.

Eisenmann-CJ & Miller-RK The effect of selenium compounds (selenite, selenate, ebselen) on the production of thromboxane and prostacyclin by the human term placenta in vitro. Toxicol-Appl-Pharmacol. 1995 Nov; 135(1): 18-24.

Emard-JF et al: Neurodegenerative diseases and risk factors: a literature review. Soc-Sci-Med. 1995 Mar; 40(6): 847-58.

Esworthy-RS et al: Expression of selenium-dependent glutathione peroxidase in human breast tumor cell lines. Cancer-Res. 1995 Feb 15; 55(4): 957-62.

Fletcher, M.P., et al. In: Nutrition and Immunology. Alan R. Liss: New York, 1988, pp. 215-239.

Florence-TM: The role of free radicals in disease. Aus-N-Z-J-Ophth. 1995 23(1): 3-7.
Foster-HD & Zhang-L. Longevity and selenium deficiency: evidence from the People's Republic of China. Sci-Total-Environ. 1995 Aug 18; 170(1-2): 133-9.

Francis, T. D.: The case for selenium deficiency promoting oxidative stress via dysfunction of the glutathione conjugating system. ICAK Journal, Winter 1996:27 - 49.

Fung-YK et al: Determination of blood mercury concentrations in Alzheimer's patients.. J-Toxicol-Clin-Toxicol. 1995; 33(3): 243-7.

Givens-TG et al: Comparison of 1% and 2.5% selenium sulfide in the treatment of tinea capitis. Arch-Pediatr-Adolesc-Med. 1995 Jul; 149(7): 808-11.

Glover, J.R. In: Proceedings of the Symposium on Selenium-Tellurium Environments. Industrial Health Foundation: Pittsburgh, 1976, pp.279-292.

Goodhart, Robert S. & Maurice E. Shills. Modern Nutrition In Health And Disease. 6th edition. Philadelphia: Lea and Febiger, 1973.

Guvenc-H et al: Low levels of selenium in mothers and their newborns in pregnancies with a neural tube defect. Pediatrics. 1995 Jun; 95(6): 879-82.

Hardell-L et al: Levels of selenium in plasma and glutathione peroxidase in erythrocytes in patients with prostate cancer or benign hyperplasia. Eur-J-Cancer-Prev. 1995 Feb; 4(1): 91-5.

Haytowitz-DB: Information from USDA's Nutrient Data Bank. J-Nutr. 1995 Jul; 125(7): 1952-5.

Hegsted, M.D. 1976. Present Knowledge In Nutrition. 4th ed. The Nutrition Foundation Pub., Washington D.C. 605.

Ip-C & Lisk-DJ: Efficacy of cancer prevention by high-selenium garlic is primarily dependent on the action of selenium.. Carcinogenesis. 1995 Nov; 16(11): 2649-52.

Jackson, M.L. In: Selnium: Present Status and Perspectives in Biology and Medicine. Humana Press: Clifton NJ, 1988, pp. 13-21.

Jameson, S.; Arfors, K.; and Hoglund, N. Pain Relief and Selenium Balance in Patients with Connective Tissue Disease and Osteoarthrosis; A Double Blind Selenium Tocopherol Supplementation Study. Nutrition Research, Supplement 1 (1985); 391-7.

Janniger-CK & Schwartz-RA: Seborrheic dermatitis.. Am-Fam-Physician. 1995 Jul; 52(1): 149-55, 159-60.

Jochum-F et al: Trace mineral status of full-term infants fed human milk, milk-based formula or partially hydrolysed whey protein formula. Analyst. 1995 Mar; 120(3): 905-9.

Johanson, N et al: Selenium status in patients with liver cirrhosis and alcoholism. British Journal of Nutrition, Vol. 55 (1986);

Kauppila, A., et al. Selenium Deficiency in Search of a Disease. Hepatology, Vol. 8, No. 2 (1988); 421-23.

Kirschmann, J.D. Nutrition Almanac: Nutrition Search. McGrew-Hill: NY. 1990.

Koivistoinen, P. Selenium deficiency in Finnish foods and nutrition: Research Strategy And Measures. Acta Pharmacology Toxicol Supp. 7 k!985), iC)4-i6.

Kok, F., et al. Selenium status and chronic disease mortality: dutch epidemiological findings. Int'l Journal of Epidemiology (1987); 329-32.

Krause, M.V. & L.K. Mahan. 1979. Food, Nutrition and Diet Therapy. 6th ed. W.B. Saunders Company, Philadelphia. 963 pp.

Kuklinski-B et al: Decreasing mortality in acute pancreatitis with sodium selenite. Clinical results of 4 years antioxidant therapy] Med-Klin. 1995 Jan 15; 90 Suppl 1: 36-41.

Lane, H., et al. The effect of selenium supplementation on selenium status of patients receiving chronic total parenteral nutrition. Journal of Parenteral and Entemal Nutrition, Vol. I 1, No. 2 (1987); 177-82.

Lee-AM et al: Inter-individual variation of selenium in maternal plasma, cord plasma and placenta. Sci-Total-Environ. 1995 Jan 10; 159(2-3): 119-27.

Levander, O.A. Ann Rev Nutr., 1987; 7: 227-250.

Levander, O.A. In: Trace Substances in Environmental Health-23. Univesity Missouri: Springfield, 1990, pp. 11-19.

Lippman, Richard D. The prolongation of life: a comparison of antioxidants and geroprotectors versus superoxide in human mitochondria. Journal of Gerontology, Vol. 36, No. 5 (1981); 550-557.

Lipsky-CL & Spear-ML Recent advances in parenteral nutrition.. Clin-Perinatol. 1995 Mar; 22(1): 141-55.

Lockitch, G. Selenium: Clinical Significance and Analytical Concepta. Vol. 27, Issue 6 (1989); 483-541.

Longnecker, G.F. In: Nutrition and Cancer Prevention: Investigating the Role of Micronutrients. Marcel Dekker: New York, 1989, pp. 389-420.

Lou-H et al: [Relation between selenium and cancer of uterine cervix]. Chung-Hua-Chung-Liu-Tsa-Chih. 1995 Mar; 17(2): 112-4.

References M - Z

Machlin-LJ: Critical assessment of the epidemiological data concerning the impact of antioxidant nutrients on cancer and cardiovascular disease. Crit-Rev-Food-Sci-Nutr. 1995; 35(1-2): 41-50.

MacPherson, A.; Taloi, k-.- and Auld, W. Selenium concentration and glutathione peroxidase activity in human blood from patients with coronary heart disease. Proc. Nutri, Soc., Vol. 46 (1987); 55A.

Mancini-M et al: Antioxidants in the Mediterranean diet.. Can-J-Cardiol. 1995 Oct; 11 Suppl G: 105G-109G.

Mandic-Z et al: Selenium content of breast milk.. Z-Lebensm-Unters-Forsch. 1995 Sep; 201(3): 209-12.

Merck Index, no. 4210.

Mulder-TP et al: Glutathione peroxidases in human head and neck cancer.. Acta-Otolaryngol-Stockh. 1995 Mar; 115(2): 331-3.

Murray, M.T. & Pizzorno, J.E. Encyclopedia of Natural Medicine. Rocklin, CA: Prima Publishing,1991.

Nakadaira-H et al: Distribution of selenium and molybdenum and cancer mortality in Niigata, Japan. Arch-Environ-Health. 1995 Sep-Oct; 50(5): 374-80.

Olson, O.E. J Am Coll Toxicol., 1986; 5: 45-70.

Orten, J.M. & Otto W. Neuhaus. 1982. Human Biochemistry. Mosby Co. St. Louis. 984.

Oskarsson-A & Sandstrom-B. A Nordic project:risk evaluation of essential trace elements: essential versus toxic levels of intake. Analyst. 1995 Mar; 120(3): 911-2.

Overad, K. et al. Cancer Lett., 1985; 27: 163-170.

Pace-GW & Leaf-CD: The role of oxidative stress in HIV disease. Free-Radic-Biol-Med. 1995 Oct; 19(4): 523-8.

Periquet-BA et al: Micronutrient levels in HIV-1-infected children.. AIDS. 1995 Aug; 9(8): 887-93.

Pfeiffer, Carl D., M.D. Mental And Elemental Nutrients. New Canaan, Conn.: Keats Publishing, 1975.

Portal-B et al: Effect of double-blind cross-over selenium supplementation on lipid peroxidation markers in cystic fibrosis patients. Clin-Chim-Acta. 1995 Jan 31; 234(1-2): 137-46.

Portal-BC et al: Altered antioxidant status and increased lipid peroxidation in children with cystic fibrosis. Am-J-Clin-Nutr. 1995 Apr; 61(4): 843-7.

Pucheu-S et al: Time-course of changes in plasma levels of trace elements after thrombolysis during the acute phase of myocardial infarction in humans. Biol-Trace-Elem-Res. 1995 Jan-Mar; 47(1-3): 171-82.

Pyyko, K.; et al. Effect of selenium supplementation to fertilizers on the selenium status of the population in different parts of Finland. European Journal of Clinical Nutrition, Vol. 42 (1988), 571-79.

Recommended Dietary Allowances. 1989. National Academy of Science, National Academy Press, Washington, D.C.

Ribalta-J et al: [Can a selenium deficiency affect the pathogenesis of cholestasis in pregnancy?] Gastroenterol-Hepatol. 1995 Mar; 18(3): 114-20.

Robinson, M. Selenium in Human nutrition in New Zealand. Nutrition Reviews, Vol. 47, No. 4 (1989)-, 99-107.

Rodriguez-Rodriguez-EM: Urinary selenium status of healthy people. Eur-J-Clin-Chem-Clin-Biochem. 1995 Mar; 33(3): 127-33.

Saito, K., et al. Interaction of zinc, copper and selenium with superoxide dismutase, catalase, and glutathione peroxidase in stomach cancer. Nutrition Research, Supp. 1 (1985); 714-24.

Salonen, J.T., et al. Am J Epidem., 1984; 120: 342-349.

Sanz-Alaejos-M & Diaz-Romero-C: Selenium in human lactation.. Nutr-Rev. 1995 Jun; 53(6): 159-66.

Schneider, Edward L. and Reed, John D. LifeExtension. The New England Journal of Medicine. Vol. 312, No. 18 (1985); 1159-68.

Shamberger, R.J., Frost, D.V. Can Med Assoc J., 1969; 100: 682.

Shamberger, R.J. Biochemistry of Selenium. Plenum: New York, 1983.

Shamberger, R. Selenium Metabolism and Function. Clinical Physiology and Biochemistry, Vol. 4, No. 1 (1986); 42-48.

Siegers, C.P. & Younes, M.: Clinical significance of the glutathione conjugative system. Pharmacological Research Communications, Vol. 15, No. 1 (1983); 2.

Singh, R.B., et al. Trace Element Med., 1991: 8; 29-33.

Smith-AM et al: Selenate fortification improves selenium status of term infants fed soy formula.. Am-J-Clin-Nutr. 1995 Jan; 61(1): 44-7.

Stone, J., et al. Reduced selenium status of patients with asthma. Clinical Science, Vol. 77 (1989); 495-500.

Sunde, R.A. Ann Rev Nutr., 1990; 10: 451-474.

Sword, J., Pope, A., Hoekstra, W. J Nutr., 1991: 121; 258-264.

Sword, J., Pope, A., Hoekstra, W. J Nutr., 1991: 121; 251-257.

Tarp, U et al: Glutathione peroxidase activity in patients with rheumatoid arthritis and in normal subjects: effects of long-term selenium supplementation. Arthritis and Rheumatism, Vol. 30, No. 10; 1162-6.

Tarp-U: Selenium in rheumatoid arthritis. A review. Analyst. 1995 Mar; 120(3): 877-81.

Tessier-F et al: Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation. Biol-Trace-Elem-Res. 1995 Jan-Mar; 47(1-3): 279-85.

Tessier-F et al: Selenium and training effects on the glutathione system and aerobic performance. Med-Sci-Sports-Exerc. 1995 Mar; 27(3): 390-6.

Tiran-B et al: Age dependency of selenium and cadmium content in human liver, kidney, and thyroid. Arch-Environ-Health. 1995 May-Jun; 50(3): 242-6.

Tolonen, M., Halme, M., Sarna, S. Biol Trace Elem Res., 1985; 7: 161- 168.

Van-Gossum-A & Neve-J: Low selenium status in alcoholic cirrhosis is correlated with aminopyrine breath test. Preliminary effects of selenium supplementation. Biol-Trace-Elem-Res. 1995 Jan-Mar; 47(1-3): 201-7.

Vehara, S.; Honjo, K.; Hirano, F.; Sakai, N.; Hirayama, A.; and Jin, K. Clinical signif-icance of selenium level in chronic pancreatitis. Journal of Clinical Biochemical Nutrition, Vol. 5 (1988), 201-7.

Walji, H., Vitamin Guide: Essential nutrients for healthy living., Element: Dorset, U.K. 1992.

Walji, H., Vitamin Minerals & Dietary Supplements., Hodder Headline Plc.: London, U.K. 1994.

Wang-WC et al: Serum selenium levels in diabetic children. A followup study during selenium-enriched agricultural fertilization in Finland. Biol-Trace-Elem-Res. 1995 Jan-Mar; 47(1-3): 355-64.

Wang-WC et al: Effect of nationwide selenium supplementation in Finland on selenium status in children with juvenile rheumatoid arthritis. A ten-year follow-up study. Analyst. 1995 Mar; 120(3): 955-8.

Westin, et al. Circulating levels of selenium and zinc in relation to nutritional status in patients with head and neck cancer. Archives of Otolaryngology Head and Neck Surgery, Vol. 115 (1989); 1079-82.

Whanger, P., et al. Blood selenium and glutathione peroxidase activity of populations in New Zealand, Oregon, and South Dakota. The Faseb Journal, Vol. 2 (1988); 2996-3002.

Williams, Sue Rodwell. Nutrition And Diet Therapy. 5th edition. St Louis: Times Mirror Mosby, 1985.

Wood-RJ et al: Mineral requirements of elderly people.. Am-J-Clin-Nutr. 1995 Sep; 62(3): 493-505.

Xia, Y.; Hill, K.; and Burk, F. Biochemical studies of a selenium-deficient population in china: measurement of selenium, glutathione peroxidase and other oxidant defence indices in blood. American Institute of Nutrition (1989); 1318-26.

Yang, G.Q., et al. In: Selenium in Biology and Medicine. AVI/Van Nostrand Reinhold: New York, 1987, pp. 589-607.

Yang, G., et al. Am J Clin Nutr., 1983; 37: 872-881.

Yu, S. et al. Biol Trace Elem Res., 1985; 7: 21-29.

Zlotkin-SH et al: Trace elements in nutrition for premature infants.. Clin-Perinatol. 1995 Mar; 22(1): 223-40.