The goal of this clinical research study is to learn the supplements Pro-Stat (which has l-arginine and also contains protein) and omega-3 fatty acids will be well tolerated in patients who have radical cystectomy for bladder cancer. Researchers also want to learn how these medications affect inflammation and recovery for these surgical patients.

This is an investigational study. Pro-Stat is not FDA-approved to treat any specific condition or disease. Omega-3 fatty acids are FDA-approved to treat high triglyceride levels. Their use to treat inflammation and help improve recovery after bladder cancer surgery is investigational.

The study doctor can explain how the supplements are designed to work.

Up to 46 participants will be enrolled in this study. All will take part at MD Anderson.

If you agree to take part in this study, you will be asked to perform a few tasks to learn about your strength, memory, and nutrition. These should take about 20 minutes to complete.

Study Groups:

You will be randomly assigned (as in the flip of a coin) into 1 of 2 study groups. This is done because no one knows if one study group is better, the same, or worse than the other group.

• If you are in Group 1, you will receive the Pro-Stat and omega-3 fatty acid supplements.
• If you are in Group 2, you will not receive the Pro-Stat and omega-3 fatty acid supplements.

You will be asked to write down any supplements you take in a diary that will be provided to you. You should write down any supplements you take for the week before and 2 weeks after surgery. Please bring this diary to your follow up appointment after surgery.

Supplement Administration:

If you are in Group 1, you will receive the omega-3 fatty acids in a pill bottle and the Pro-Stat in foil packets. You should take each supplement 4 times daily. Omega-3 fatty acid capsules should be swallowed whole and should not be opened, chewed, or crushed.

Packets of Pro-Stat may be mixed with other liquids or food. If vomiting occurs, do not replace the vomited dose. If you miss a dose, you may take an extra dose that same day.

You should bring all supplements you haven't taken with you to your 14 day visit after surgery.

Length of Study Participation:

Your doctor may lower the dose of the supplements if you experience any serious side effects that may be related to the supplements. If these side effects continue after the dose has been lowered, you will no longer be able to take the supplements. You may also be taken off study if you are unable to follow study directions.

Your participation on the study will be over after the follow-up visits.

Surgery:

You will have your standard-of-care surgery. You will receive a separate consent for the surgery that explains the procedure and the risks.

Study/Follow-Up Visits:

Before Surgery:

• Blood (about 8 teaspoons) will be drawn for routine tests, protein testing, biomarker testing, to check your cholesterol, liver function, your amino acid levels, and to test for inflammatory markers. Biomarkers are found in the blood and may be related to your reaction to the supplements.
• Urine will be collected for routine tests.
• Blood (about 4 teaspoons) will also be drawn and stored at MD Anderson for future testing as a part of this study.

Day 1 After Surgery:

• Blood (about 2 teaspoons) will be drawn for routine tests.
• Blood (about 4 teaspoons) will also be drawn and stored at MD Anderson for future testing as a part of this study.

Day 2 After Surgery, blood (about 2 teaspoons) will be drawn for routine tests.

Day 3 After Surgery:

• Blood (about 2 teaspoons) will be drawn for routine tests.
• Blood (about 4 teaspoons) will also be drawn and stored at MD Anderson for future testing as a part of this study.

On your Day of Discharge from the hospital:

• Blood (about 2 teaspoons) will be drawn for routine tests.
• Urine will be collected for routine tests.

Day 14 After Surgery:

• Blood (about 2 teaspoons) will be drawn for routine tests, to check your cholesterol, your liver function, and your amino acid levels.
• Urine will be collected for routine tests.
• Blood (about 4 teaspoons) will also be drawn and stored at MD Anderson for future testing as a part of this study.

You weight will be measured at all of the above visits and information will be collected from your medical record.

Day 90 After Surgery, you will have a physical exam and your weight will be recorded.

Inclusion Criteria:

1. All patients undergoing RC for bladder cancer with urinary diversion at MD Anderson Cancer Center (MDACC). All races and ethnicities will be included
2. Patients must be willing to spend time for the study
3. Patient must provide signed informed consent.
4. Male or female, age >/= 18 years.
5. Adequate hepatic function: alkaline phosphatase </= 1.5 x Upper Limit of Normal (ULN); total bilirubin, aspartate aminotransferase (AST), and Alanine aminotransferase (ALT) </= 1.5 x ULN; international normalized ratio (INR) <1.3 (or <3 if on anticoagulant therapy).

Exclusion Criteria:

1. Subjects will be excluded if they do not attend pre-operative clinic dedicated to RC subjects.
2. Subjects with allergies to any supplements.
3. Subjects with galactosemia will be excluded.
4. Subjects may be excluded if they have known autoimmune inflammatory disease. (e.g. rheumatoid arthritis, ulcerative colitis, gout, chronic steroids).
5. Hepatic impairment: alkaline phosphate > 1.5 x ULN; total bilirubin, AST, and ALT > 1.5 x ULN; INR >1.3 (or >3 if on anticoagulant therapy).
6. Previously unable to tolerate either supplement due to taste or gastrointestinal (GI) side effects.
7. Any active malignancies being treated other than bladder cancer (incidentally found prostate cancer at RC is acceptable).
8. Unwillingness or inability to comply with mandated blood draws.
9. Any previous immunotherapy with immune checkpoint inhibitors such was Nivolumab, Atezolizumab and others in the class