Soy Bread Diet in Improving Immune Function in Participants With Prostate Cancer

PRIMARY OBJECTIVES: I. To precisely define the impact of soy on myeloid derived suppressor cells (MDSC) in a human model clinical trial. OUTLINE: Participants are randomized to 1 of 2 arms. ARM I (SOY BREAD): Participants consume 2 slices of soy bread daily for approximately 20 weeks in the absence of unacceptable toxicity. Concurrent with the intervention, participants will be staring androgen deprivation therapy at the direction of their medical oncologist. ARM II (WHEAT BREAD): Participants consume 2 slices of wheat bread daily for approximately 20 weeks in the absence of unacceptable toxicity. Concurrent with the intervention, participants will be staring androgen deprivation therapy at the direction of their medical oncologist.