Cancer Prevention by Different Forms of Selenium
Following the reports of an inverse association between the dietary intake of selenium and cancer incidence, research spanning decades has investigated this association. The effort has included extensive studies in cultured cell and animal models. With promising results from these studies, as well as observational studies indicating that lower selenium levels were associated with increased cancer risk for several organ types, human supplementation trials were performed. However, the results of these clinical trials did not demonstrate a beneficial reduction in cancer risk for those receiving the selenium supplement. One possible explanation for these disappointing results is the different forms of selenium that have been used for this research, and this possibility is considered in this chapter.