Cholecalciferol and Genistein Before Surgery in Treating Patients With Early Stage Prostate Cancer

Inclusion Criteria:

* Participants must have microscopic confirmation of adenocarcinoma of the prostate within three months of randomization; clinical stage T1 and T2 a, b, or c are allowed
* Participants' prostate cancer must be confined to the prostate (in the clinical judgment of the treating physician)
* Participants must be candidates for prostatectomy
* Participants must have Eastern Cooperative Oncology Group (ECOG) performance status =\<1 (Karnofsky \>= 70%)
* White blood cell (WBC) within normal limits
* Platelets \>= 100 K/uL
* Hemoglobin \>= 10 g/dL
* Thyroid-stimulating hormone (TSH) =\< 4.20 uIU/mL
* Free T4 =\< 12.5 ng/dL
* Bilirubin within upper limit of normal
* Aspartate aminotransferase (AST) =\< 1.5 x upper limit of normal
* Creatinine =\< 2.0 mg/dL
* Serum calcium: within institutional normal limits
* Participants must agree to stop taking nonsteroidal anti-inflammatory drugs (NSAIDS) during the course of the study, however, low dose aspirin (\< 100 mg/day) will be allowed; no wash out period is required
* Participants must be willing to discontinue consuming soy products and ingesting vitamin supplements while participating in this study
* The effects of cholecalciferol and genistein on the developing human fetus at the recommended therapeutic doses are unknown; for this reason, participants must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) for the duration of study participation
* Participants must have the ability to understand and sign a consent form indicating the investigational nature of the treatment and its potential risks

Exclusion Criteria:

* Participants may not have received any prior therapy for prostate cancer including: chemotherapy, hormonal therapy, brachytherapy, or external radiation
* Participants may not be receiving concurrent systemic therapy for other cancers
* Participants may not be receiving any other investigational agents
* Participants may not be taking the following p450 inducers and inhibitors: carbamazepine, clarithromycin, fluconazole, fosphenytoin, itraconazole, ketoconazole, phenobarbital, phenytoin, rifabutin, rifampin
* Participants who took finasteride or dutasteride within 6 months of the pre-randomization biopsy, are currently taking finasteride or dutasteride, or are planning on taking these agents during study participation
* Participants with a history of allergic reactions attributed to genistein or placebo, or compounds of similar chemical or biologic composition
* Participants with uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
* Participants requires thyroid replacement therapy; Note: participants with a history of thyroid disease \> 5 years ago, with current normal thyroid function, will be considered eligible
* Participant has current, known nephrolithiasis or a history of nephrolithiasis within the past 5 years
* Participant has any history of sarcoidosis