Introduction

Abstract

Historically, the image of selenium has changed dramatically over the last century. Initially, selenium was widely considered to be a toxic agent in mammals. In the 1930s, this element was found to be responsible for severe illnesses that had been documented, primarily in livestock, many years earlier [reviewed in 1]. Thus, it was quite surprising when Schwarz and Foltz reported in 1957 [2] that selenium prevented liver necrosis in rats. This finding and a report that selenium was important in anaerobic growth of Escherichi coli when grown on glucose [3] provided evidence that selenium was an important micronutrient for mammals and for certain bacteria.