ABSTRACT
Selenium (Se) and its several species have been demonstrated to be essential for living organisms, including animals and humans (Pinset 1954). This element is required to obtain the biologically active selenol group (-SeH), which is a precursor of glutathione peroxidase, thioredoxin reductase and other seleno-containing enzymes involved in oxidative stress response (Holben and Smith 1999). Even though plants represent the main source of this element for animal diets, it is not essential for them. Since confi rmation of the essentiality of Se, evaluation of its nutritional status is a crucial task to establish the right doses avoiding defi ciency-linked diseases and promoting good health conditions (Lei et al. 2011). However, Se has a narrow interval between toxicity and essentiality, which is puzzling toxicologists and alarming nutritionists and legislators. Different diseases can be caused by its defi ciency, but it can be toxic from levels one order of magnitude
1Laboratory of Analytical Chemistry for Research and Development (QUIANID), Instituto de Ciencias Básicas, Universidad Nacional de Cuyo, Padre Jorge Contreras 1300, Parque Gral. San Martín, C.P. M5502JMA Mendoza, Argentina. 2Consejo Nacional de Investigaciones Científi cas y Técnicas (CONICET), Argentina. *Corresponding author: rwuilloud@mendoza-conicet.gob.ar
higher than that required for good health (Wada et al. 1995). Thus, daily consumption of food containing less than 0.1 mg/kg of body weight will result in Se defi ciency, whereas dietary levels above 1 mg/kg may lead to toxicity (Wada et al. 1995).
