BCG is the "standard of care" for NMIBC. Its purpose is to kick up the immune system so that it repels the cancer cells in the bladder lining. It would be foolhardy to take ANYTHING that might interfere with this.
Do not take any other medications or pseudo-meds without checking with your urological team first. The things that you mention have no known therapeutic effects in treating bladder cancer.
As for vitamins, there are several formulations that are SOLD with the idea that they might "improve" bladder "health."
These have been endorsed by some...not all, by any means....urologists. Discuss this with your urologist and he/she can tell you about them.
Diagnosis 2-08 Small papillary TCC; CIS
BCG; BCG maintenance
Vice-President, American Bladder Cancer Society