I had the very same question for my urologist when I began my BCG treatments. (Nine installations so far, six then three, with one NED cystoscopy and another scheduled next month). Because I believe healthy eating is paramount with any healing, I was hoping for specific suggestions, but of course no food is a silver bullet. As another poster observed, bolstering the immune system is recommended. My urologist recommended I eat adequate protein, but I'm a vegetarian, so that means a variety of fresh fruits and veggies, nuts, legumes and avoiding sugar and empty calories. Selenium strengthens the immune system and there are lots of good sources. I'm eating more mushrooms and brazil nuts. If nothing else, it feels empowering to take an active part in one's cancer journey. Best of luck to you!