Abstract
Whole-body selenium is regulated by excretion of the element. Reports of studies carried out using isotopic tracers have led to the conclusion that urinary selenium excretion is regulated by selenium intake but that fecal excretion is not. Because of the limitations of tracer studies, we measured urinary and fecal selenium excretion by mice with selenium intakes in the form of sodium selenite ranging from deficient to almost toxic. Tissue and whole-body selenium concentrations increased sharply between deficient and adequate selenium intakes, reflecting tissue accumulation of selenium in the form of selenoproteins. Once the requirement for selenium had been satisfied, a 31-fold further increase in intake resulted in less than doubling of tissue and whole-body selenium, demonstrating the effectiveness of selenium excretion by the mouse. Urinary selenium excretion increased with increases in dietary selenium intake. Fecal selenium excretion, which was 20 to 30 % of the selenium excreted in the physiological range, responded to moderately high selenium intake but did not increase further when selenium intake was increased to even higher levels. Thus, fecal selenium excretion contributes to regulation of whole-body selenium at physiological selenium intakes. The pattern of its response to the full spectrum of selenium intakes was different from the urinary excretion response, suggesting that the mechanisms of fecal and urinary routes of excretion are different.
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Acknowledgments
The work presented here was supported by National Institutes of Health (USA) grants ES02497 and ES00267 and by the National Council for Scientific and Technological Development, Brazil (Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq) grant #200580/2010-8 (to LFCP).
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None of the authors has a financial or scientific conflict of interest related to the work reported in this paper.
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Pedrosa, L.F.C., Motley, A.K., Stevenson, T.D. et al. Fecal Selenium Excretion Is Regulated by Dietary Selenium Intake. Biol Trace Elem Res 149, 377–381 (2012). https://doi.org/10.1007/s12011-012-9430-9
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DOI: https://doi.org/10.1007/s12011-012-9430-9