Selenium-poor food

The northern parts of Europe produce selenium-poor foods. Selenium consumption in Germany is low, on average, amounting to between 40 and 90 jg per day. The normal selenium requirement of women and men is not met in every case, and selenium deficiency in German is common (Drobner 1997, Anke et al. 2002, 2003). Vegetarians, on average, take in less selenium than people with mixed diets. 

Differences in the selenium content of foodstuffs are due in part to geographical differences in the amounts of the element that are transferred from soil to the food chain. Selenium-deficiency diseases related to selenium-poor soil are recognized in parts of China and elsewhere, but soils rich in selenium (above 5 ppm) are found in parts of the United States. The selenium in most plant-derived foods, present substantially as selenomethionine (SeMet) and selenocysteine (SeCys) derivatives, has reasonably good bioavailability. However, in animal-derived foods selenium has a wide range of bioavailability as assessed by its ability to increase liver concentrations and glutathione peroxidase activity. 

Similar demands for speciation of trace elements exist for food analysis. Substantial differences in the biological availability are known for several essential elements and depend on the form in which they are present in the diet. The chemical bases for these differences are known for cobalt, iron, and chromium but not for zinc, copper, and selenium. The importance of speciation in food analysis is best demonstrated by the example of iron. That element, when part of heme compounds, is well absorbed, and there is little influence on the absorption by other factors in the diet. Nonheme iron, on the other hand, is not readily absorbed and, in addition, is subject to many influences from dietary ingredients those influences are poorly understood and probably not completely known (14). 

In addition to selenosugars, there are smaller quantities of other currently unknown selenium species in urine. The presence of selenomethionine has also been reported in some urine samples, but its likely origin is D-selenomethionine, deliberately ingested in those experiments and shown to be poorly metabolized in comparison with L-selenomethionine. The inorganic selenium species, selenite and selenate, which are also likely to be ingested in significant quantities in food and water, are not usually detected in urine. ... 

---