Se-Methyl-Seleno-L-Cysteine or Selenomethionine in Preventing Prostate Cancer in Healthy Participants

PRIMARY OBJECTIVES: I. To determine the individual toxicity profiles of Se-methyl-seleno-L-cysteine (methyl selenocysteine; MSC) and selenomethionine (SeMet) administered to cohorts of men daily for twelve weeks, with dose escalation with each successive cohort. SECONDARY OBJECTIVES: I. To measure the pharmacokinetics of selenium, according to form (MSC vs SeMet): MSC and SeMet impacts on plasma, albumin, and urinary concentrations of selenium over 48 hours on dosing days 1 and 84. II. To evaluate the pharmacodynamics of selenium by form (MSC vs SeMet): plasma, albumin, and urinary Selenoprotein P (Sepp1) concentrations and glutathione peroxidase (GPx) activity over 48 hours on dosing days 1 and 84. III. To store plasma and formed elements (red cells plus platelets) for future analysis of methyl selenol and other key selenium species, when those assays become available. OUTLINE: This is a dose-escalation study. Participants are randomized to 1 of 3 treatment arms. ARM I: Participants receive Se-methyl-seleno-L-cysteine orally (PO) on days 1-84. ARM II: Participants receive selenomethionine PO on days 1-84. ARM III: Participants receive placebo PO on days 1-84. After completion of study treatment, patients are followed up on day 112.