Selenium adults

The reference interval for selenium in whole blood, plasma or serum, hair, and nails should be established locally, since these indices are affected by dietary selenium intake. Plasma selenium adult values lie in the interval 63 to 160pg/L (0.8 to 2.0pmol/L). Values of less than 40 pg Se per L (0.5pmoI/L) indicate probable selenium depletion. 

Necheles et al. (N4) first reported a genetically determined homozygous GSH-Px deficiency associated with neonatal jaundice and mild hemolysis. Spontaneous recovery from hemolysis was noted 3 months after birth. Thereafter, several cases with GSH-Px deficiency were reported. Newborn infants exhibit significantly lower red blood cell GSH-Px activity and serum selenium concentrations than adult control subjects, and a significantly positive correlation between selenium concentration and GSH-Px activity has been observed. Furthermore, the addition of selenium stimulates, both in vivo and in vitro, the GSH-Px activity. The neonatal red blood cell GSH-Px deficiency may be partially due to insufficient availability of selenium during pregnancy (P9). Therefore, the diagnosis of GSH-Px deficiency in newborn infants must be made carefully. 

Selenomethionine group had altered immune function, altered serum enzyme activities, and elevated concentrations of selenium in liver (4 times control values) and breast muscle (14 times). Sodium selenite-treated birds had normal immune function and selenium tissue burdens however, serum enzyme activity was disrupted in the 3.5 mg/L group Adults normal. Impaired reproduction (reduced survival of ducklings, increased developmental abnormalities) for selenomethionine occurs between 4 and 8 mg/kg ration selenocysteine did not impair reproduction at 16 mg Se/kg ration... 

Adults fed diets for 11 weeks containing 5 or 9 mg Se/kg DW ration as seleno-L-methionine or naturally incorporated selenium (mammals from Kesterson National Wildlife Refuge, California)... 

Felton, S.P., W. Ji, and S.B. Mathews. 1990. Selenium concentrations in coho salmon outmigrant smolts and returning adults a comparison of wild versus hatchery-reared fish. Dis. Aquat. Organ. 9 157-161. 

Aquatic birds nesting at Kesterson Reservoir in 1983 were found to have high rates of embryo deformities and mortality. Beginning in 1984, adult birds were also found dead in unusually high numbers. Through a series of field and laboratory studies, these effects were attributed to the exceptionally high concentrations of selenium in the biogeochemical food web of the birds. 

Selenium is readily available in a variety of foods including shrimp, meat, dairy products, and grains, with a recommended daily intake of 55 to 70 jug. It occurs in several forms with Se+6 being biologically most important. Selenium is readily absorbed by the intestine and is widely distributed throughout the tissues of the body, with the highest levels in the liver and kidney. It is active in a variety of cellular functions and interacts with vitamin E. Selenium appears to reduce the toxic effects of metals such as cadmium and mercury and to have anticarcinogenic activity. Selenium produces notable adverse effects both in deficiency and excess thus recommended daily intake for adults is approximately 70 Jg/day but should not exceed 200 pg/day. 

Greger, J. L., Smith, S. A., and Snedeker, S. M. (1981). Effect of dietary calcium and phosphorus levels on the utilization of calcium, phosphorus, magnesium, manganese, and selenium by adult males. Nutr. Res. 1, 315-325. 

In large areas of the world, the soils contain very little selenium in forms that can be taken up by plants. Crops produced in these areas are, therefore, very low in selenium. A selenium (deficiency in livestock is a serious problem. A deficiency causes a form of muscular dystrophy in younger animals and poor reproductive qualities in the adult animals. For prevention, sodium selenate or sodium selenite, sometimes augmented with vitamin E. is added in proper proportions to feedstuffs Some areas, including the Plains and Rocky Mountain states in the United States have soils that are rich in available selenium. Tn regions like these, selenium toxicity is a problem. The situation is particularly senous in Arizona, California, Montana, Nevada, New Mexico, and South Dakota. 

It is well known that the toxicity of many elements depends on the physicochemical forms they assume. So, for instance, determining the total content of a certain element in a sample is definitely not sufficient to measure its toxicity. Selenium is a case in point in small amounts this element is essential to human health. But the transition from the necessary amount (about 70pg of selenium per day for an adult) to a toxic dose (about 800 pg of selenium per day) is relatively easy. In rats, moreover, the fatal dose of Se(IV) compounds is 3.2 mg kg 1 of body mass, whereas for dimethyl selenide it is 1600 mg kg 1 of body mass. Nonorganic selenium compounds [Se(IV) and Se(VI)] are believed to be the most toxic ones, whereas in the environment selenium occurs most commonly bound to amino acids (selenomethionine and selenocysteine). The least toxic forms seem to be the volatile methyl compounds of selenium, which are metabolites of a detoxication process. 

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