The investigators hypothesize high-dose vitamin D supplementation will reduce androgen deprivation therapy (ADT)-related side effects including ADT-induced bone loss, decreased muscle mass, falls, reduced muscle strength, and diminished physical performance in older prostate cancer patients. The vitamin D supplementation is aimed at reducing fracture risk by maintaining proper bone density, thereby preventing osteoporotic/osteopenic conditions and increasing muscle mass. Both vitamin D and exercise are efficacious in maintaining proper bone health and muscle mass among the general population, but little research has been done on prostate cancer patients and survivors. Vitamin D could reduce fracture risk among prostate cancer survivors.
