Mohr, Katherine. Selenium. Knh 413 Medical Nutrition Therapy II. Miami University, Oxford, Ohio, Spring 2013



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Mohr, Katherine. Selenium. KNH 413 – Medical Nutrition Therapy II. Miami University, Oxford, Ohio, Spring 2013.
Selenium
Selenium is a trace mineral, meaning it is needed in amounts less than 100 mg per day.

RDA/AI

Adults ages 19 and over: 55 µg

Pregnant women, all ages: 60 µg

Lactating women, all ages: 70 µg

Teens ages 14-18: 55 µg

Children ages 9-13: 40 µg

Children ages 4-8: 30 µg

Children ages 1-3: 20 µg

Infants ages 7-12 months: 20 µg

Infants ages 0-6 months: 15 µg

Tolerable upper intake level

Adults ages 19 and over: 400 µg

Teens ages 14-18: 400 µg

Children ages 9-13: 280 µg

Children ages 4-8: 150 µg

Children ages 1-3: 90 µg

Infants ages 7-12 months: 60 µg

Infants ages 0-6 months: 45 µg


Function

Component of glutathione peroxidase antioxidant enzyme system—it spares vitamin D and prevents oxidative damage to cell membranes

Immune function

Production of thyroxine (thyroid hormone)


Metabolism

Absorption of selenium occurs in the duodenum and jejunum of the small intestine and occurs more readily in conditions of deficiency. Excess selenium is excreted via urine.

In the body, selenium is stored as selenomethionine, and selenocysteine is the active form.

Selenium is transported bound to albumin and then later to α2-globulin.

During stress, infection, or tissue injury, glutathione peroxidase selenium enzyme may protect against the damaging effects of peroxides and oxidized free radicals.

A selenoprotein enzyme called type I iodothyronine 5’-deiodinase converts thyroxine (T4) to triiodothyronine (T3).

Vitamin E and selenium may function together in their antioxidant roles, reinforcing one another’s protective effects against harmful oxidation. Glutathione peroxidase functions in the mitochondria and the cytosol of cells, while vitamin E functions in the cell membrane.



Disease States that Alter Metabolism

Impaired absorption: Crohn’s disease, Celiac disease, and other GI tract conditions; resection or surgical removal of the stomach

Food Sources

Liver, kidney, pork, seafood (tuna, cod, shrimp, halibut), poultry (turkey, chicken), Brazil nuts, wheat, rice (depending on the soil content)

Tests for assessing nutrient metabolism

Measure selenium or glutathione peroxidase amounts in serum, platelets, or erythrocytes or in whole blood. Erythrocyte selenium is a more long-term marker of selenium intake. Urine samples and toenail clippings may also aid in selenium level assessment.

Drug-Nutrient Interactions

Anticoagulant medications: aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others

Taking selenium with these medications may increase chances of bruising and bleeding because selenium also slows blood clotting.


Statin drugs: atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), and pravastatin (Pravachol)

Taking selenium, beta-carotene, vitamin C, and vitamin E together might decrease the effectiveness of some cholesterol-lowering medications.


Sedative (Barbiturates) medications: Taking selenium with these drugs may increase the effects and side effects of these drugs because it alters the metabolism of these drugs.

Nutrient Measurement

Measure selenium or glutathione peroxidase amounts in serum, platelets, or erythrocytes or in whole blood. Erythrocyte selenium is a more long-term marker of selenium intake.

Deficiency Signs and Symptoms

Impaired immune functions, increased risk of viral infections, infertility, depression, hostility, impaired cognitive function, and muscle pain and wasting
Diseases that can result:

Keshan disease (enlarged heart and poor heart function, occurs in selenium deficient children)

Kashin-Beck disease (osteoanthropathy: deforming arthritis)

Myxedematous endemic cretinism (mental retardation)



Toxicity Signs and Symptoms

Selenosis: gastrointestinal upsets, hair loss, white blotchy nails, garlic breath odor, fatigue, irritability, and mild nerve damage

Works Cited

Mahan, L. K. & Escott-Stump, S. (2004) Food, nutrition, & diet therapy. Elsevier: Philadelphia.

Office of Dietary Supplements: National Institutes of Health. (October, 2012). Selenium. Retrieved April 7, 2013, from http://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/



WebMD. (February, 2009). Selenium interactions. Retrieved April 7, 2013, from http://www.webmd.com/vitamins-supplements/ingredientmono-1003-SELENIUM.aspx?activeIngredientId=1003&activeIngredientName=SELENIUM&source=2&tabno=6


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