Deficiency selenium

SELENIUMANDSELENIUMCOMPOUNDS] (Vol21) -from selenium deficiency [MINERAL NUTRIENTS] (Vol 16)... 

Selenium is an essential element and is beneficial at low concentrations, serving as an antioxidant. Lack of selenium affects thyroid function, and selenium deficiencies have been linked to Keshan Disease (34). Selenium at high levels, however, is toxic. Hydrogen selenide (which is used in semiconductor manufacturing) is extremely toxic, affecting the mucous membranes and respiratory system. However, the toxicity of most organ oselenium compounds used as donor compounds for organic semiconductors is not weU studied. 

Pure selenium deficiency, without concurrent vitamin E deficiency, is not generally seen except in animals on experimental diets (113). In China, selenium deficiency in humans has been associated with Keshan disease, a cardiomyopathy seen in children and in women of child-bearing ages, and Kashin-Beck disease, an endemic osteoarthritis in adolescents (113). 

There are areas (22) where selenium levels in the soil are very low these include regions of volcanic activity like that adjacent to the Cascade mountains in the Pacific Northwest states of the United States and the central north island of New Zealand. There, because the heat of emption volatilized the selenium, the residual soil parent material is virtually devoid of selenium. Other areas of low soil-selenium reflect leaching of selenium out of the top soil, as in the Canterbury plain on New Zealand s south island. Areas of selenium deficiency have negative implications for animal and human health. 

In 1956 selenium was identified (123) as an essential micronutrient iu nutrition. In conjunction with vitamin E, selenium is effective iu the prevention of muscular dystrophy iu animals. Sodium selenite is adrninistered to prevent exudative diathesis iu chicks, a condition iu which fluid leaks out of the tissues white muscle disease iu sheep and infertility iu ewes (see Eeed ADDITIVES). Selenium lessens the iacidence of pneumonia iu lambs and of premature, weak, and stillborn calves controls hepatosis dietetica iu pigs and decreases muscular inflammation iu horses. White muscle disease, widespread iu sheep and cattle of the selenium-deficient areas of New Zealand and the United States, is insignificant iu high selenium soil areas. The supplementation of animal feeds with selenium was approved by the U.S. EDA iu 1974 (see Eeed additives). Much of selenium s metaboHc activity results from its involvement iu the selenoproteia enzyme, glutathione peroxidase. 

Selenium deficiency has been identified iu humans iu a broad area of China, stretching from the northeast to the southwest. Two syndromes are evident Keshan disease, an endemic cardiomyopathy which affects children, and Kashin-Beck disease, an edemic osteoarthropathy (big-joiat), also mainly involving children, which occurs iu eastern Siberia and parts of China. As a result of these observations, a protective effect for selenium has been proposed, and various selenium-containing preparations have been appHed to preserve animal and human health. 

Asayama, K., Kooy, N.W. and Burr, I.M. (1986). Effect of vitamin E deficiency and selenium deficiency on insulin reserve and free radical scavenging systems in islets decrease of islet manganosuperoxide dismutase. J. Lab. Clin. Med. 107, 459-463. 

Keshan disease (selenium deficiency) Sickle cell anaemia... 

Water soluble Se in the North West region varied from 0.0002-0.0429 mg/kg. Water soluble Se accounted for 2.13-6.34% of the total Se in the soils of North China. Selenium is an essential element to animals and humans. When water soluble Se in soils is less than 0.003 mg/kg, Se deficiency in animal and human beings may occur. EDTA-extractable Se in the alkali desert soils of North China was in the range of 0.011-0.090 mg/kg this was about 5-11% of the total Se in the soils. Selenium deficiency was mostly found in the Loess Plateau and Tibet region. NH4OAc-cxtractable Ni in soils from Beijing was 0.29 mg/kg. 

Selenium deficiency in humans occurs in the loessial region of the North China and Tibet Plateau of China (Liu, 1996). The arid and semi-arid soils in these areas of China contain low total Se in their parent materials. 

Selenium is an essential trace element for optimal health but an excess is toxic. The British population is now reckoned to be selenium deficient because more European wheat is now used to make bread at the expense of North American wheat. The difference in the selenium content is caused by the difference in the selenium content of the soils. In geological terms, European soil is older and the selenium has washed out. 

Proposed criteria for prevention of selenium deficiency and for protection against selenosis... 

Day-old chicks fed selenium-deficient diets plus 100 mg Zn/kg FW, as zinc oxide, purified ration for 9 days Hens fed diets containing 218, 257, 1762, or 1861 mg Zn/kg diet for up to 40 weeks... 

Keating, K.I. and P.B. Caffrey. 1989. Selenium deficiency induced by zinc deprivation in a crustacean. Proc. Natl. Acad. Sci. (USA) 86 6436-6440. 

Selenium deficiency is not as well documented as selenium poisoning, but may be equally significant. 

The availability of selenium to plants may be lessened by modem agricultural practices, eventually contributing to selenium deficiency in animal consumers. For example, fertilizers containing nitrogen, sulfur, and phosphorus all influence selenium uptake by plants through different... 

There is a comparatively narrow concentration range separating effects of selenium deficiency from those of selenosis. 

Accordingly, the proposed selenium criteria shown in Table 31.5 for prevention of selenium deficiency and for protection of aquatic life, livestock, crops, and human health, should be viewed as guidelines, pending acquisition of additional, more definitive, data. 

Table 31.5 Proposed Criteria for Prevention of Selenium Deficiency and for Protection Against Selenosis (Values are in mg of selenium/kg fresh weight [FW] or dry weight [DW].)...

PREVENTION OF SELENIUM DEFICIENCY Rainbow trout (water levels of 0.4 pg Se/L) ... 

Documented biological responses to selenium deficiency or to selenosis vary widely, even among closely related taxonomic groups. 

Flueck, W.T. 1994. Effect of trace elements on population dynamics selenium deficiency in free-ranging black-tailed deer. Ecology 75 807-812. 

Flueck, W.T. and J.M. Smith-Flueck. 1990. Selenium deficiency in deer the effect of a declining selenium cycle Trans. 19th Inter. Union Game Biol., Trondheim, Norway 1989 292-309. 

Jensen, L.S. 1968. Selenium deficiency and impaired reproduction in Japanese quail. Proc. Soc. Exp. Biol. Med. 128 970-972. 

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