Fundamentals of Human Nutrition/Selenium

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11.4 Selenium[edit]

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11.4.1 Sources[edit]

Selenium can be found in animal based foods, plant based foods and in a dietary supplement. For animal based foods, a good source of selenium is found in organ meats, such as the liver, and seafood (Sunde). Selenium can also be found in plant based food such as nuts and grains. The highest source of selenium is found in Brazil Nuts. Brazil Nuts contains about 544 mcg of selenium per serving (Thomson et al., 2008). This amounts to over 700% of the daily value established by the FDA. A poor source of selenium containing foods are found in vegetables, fruit and diary (Tinggi et., 1992).

The concentration of selenium found in plant based food is effected by several environmental factors. The pH and selenium concentration of the soil influence the selenium concentration in food (Rayman, 2008). Thus the amount of selenium found in food is a variable of geographical location. In areas that are low in selenium concentrations, farmers will add selenium into their fertilizer or livestock feed to increase selenium concentration.

There are different chemical forms of selenium found in food. The chemical forms are characterized as organic or inorganic compounds. The organic and most abundant forms found in food are selenocysteine and selenomethionine (“7 Selenium”). Selennocysteine is found in animal selenoproteins. Selenomethionine is found inside the muscle tissue of animals. However it is initially synthesized inside plants. Humans are incapable of producing selenomethionine, it must be consumed from food. About 90 percent or more of Selenomethionine is absorbed into the body (Swanson et al., 1991). This form of selenium is predominantly found in animal and plant based products. The two major inorganic forms are selenites and selenates. Selenates (SeO42-) has a high absorption rate. Almost all of it is absorbed into the body, however a significant amount is loss and excreted with urine. On the other hand, Selenites ( SeO32-) does not have as high of an absorption rate as selenates, but it does have a higher retention rate (Thomson and Robinson, 1986). In contrast to selenomethionine, only about 50 % of selenites is absorbed by the body. (Thomson and Robinson, 1986).Selenites and selenates are traditionally found in animal feeds and dietary supplements.

All three major forms of selenium, selenomethionine, selenates and selenites are found in dietary supplements.

A list the top 10 Selemium containing foods is listed below:

Brazil nuts Yellow fin Tuna Halibut Sardines Ham Canned shrimp Enriched macaroni Beef steak Turkey Beef liver

Note: This list is compiled from the USDA National Nutrient Database for Standard Reference, Release 25

Reference page:

"7 Selenium." National Research Council. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: The National Academies Press, 2000.

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.

Sunde RA. Selenium. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern Nutrition in Health and Disease. 11th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012:225-37

Swanson CA, Reamer DC, Veillon C, King JC, Levander OA. 1983. Quantitative and qualitative aspects of selenium utilization in pregnant and nonpregnant women: An application of stable isotope methodology . Am J Clin Nutr 38:169–180

Thomson CD, Chisholm A, McLachlan SK, Campbell JM. Brazil nuts: an effective way to improve selenium status. Am J Clin Nutr. 2008 Feb;87(2):379-84. [PubMed abstract]

Tinggi U, Reilly C, Patterson CM. Determination of selenium in foodstuffs using spectrofluorometry and hydride generation atomic absorption spectrometry. J Food Comp Anal. 1992;5:269–80

Rayman MP. Food-chain selenium and human health: emphasis on intake. Br J Nutr 2008;100:254-68

U.S. Department of Agriculture, Agricultural Research Service. USDA National Nutrient Database for Standard Reference, Release 25. Nutrient Data Laboratory Home Pageexternal link disclaimer, 2012

11.4.2 Functions[edit]

11.4.3 Requirements[edit]

11.4.4 Imbalance[edit]