Nutrition Therapy in Improving Immune System in Patients With Bladder Cancer That Can Be Removed by Surgery

Inclusion Criteria: * Patients must have a tissue diagnosis of primary cell carcinoma of the bladder by transurethral resection of bladder tumor (TURBT) or partial cystectomy; patients may not have any evidence of unresectable disease or metastatic disease as assessed by exam under anesthesia or imaging (computed tomography \[CT\], magnetic resonance imaging \[MRI\], positron-emission tomography \[PET\]) * There must be plans for the cystectomy to be performed within 28 calendar days after registration * Surgery must be planned to be performed under pre-approved, study-specific surgical guidelines * Patients must have completed any neoadjuvant chemotherapy or immunotherapy (intravesical or systemic) \>= 14 calendar days prior to registration and any toxicities resolved to at least grade 2 * Patients may have a history of radiation therapy; radiation therapy must have been completed \>= 180 days prior to registration * Patients may have a history of prior partial cystectomy; prior partial cystectomy must have been completed at least 180 days prior to registration * Patients with planned adjuvant chemotherapy within 90 days after radical cystectomy will not be eligible * Patients must be able to swallow liquid and have no refractory nausea, vomiting, malabsorption, or significant small bowel resection that would preclude adequate absorption; patients on tube feeding are not eligible * Patients must have their baseline nutrition status assessed using the Scored Patient-Generate…