SeleniumNailsSelenoproteinsGlutathione PeroxidaseSelenious AcidSelenoprotein PSelenomethionineWhite Muscle DiseaseToesTrace ElementsOrganoselenium CompoundsSelenium CompoundsVitamin EHairDietSpectrophotometry, AtomicDietary SupplementsAntioxidantsSelenic AcidSelenium RadioisotopesCase-Control StudiesRisk FactorsProspective StudiesProstatic NeoplasmsFollow-Up StudiesLiverSelenocysteineSelenium OxidesOdds RatioMultivariate AnalysisTumor Markers, Biological