Calcitriol or Placebo in Men for Prostate Cancer Active Surveillance

After the diagnosis of prostate cancer, many men alter their lifestyle or diet or use various supplements in an attempt to retard the growth of their cancer. While there is limited data on the use of diet and supplements to alter the risk of prostate cancer, even less is known regarding the ability of diet or supplements to alter progression. For men who have elected active surveillance, the investigators propose to investigate the ability of vitamin D to retard the growth of prostate cancer.