Why do some physicians advise patients with a bladder infection to drink a lot of cranberry juice? Answer Cranberry juice contains chemicals that kill viruses and bacteria. The increased volume of fluid in the bladder causes bacterial cells to burst as they absorb the excess fluid. Cranberry juice makes the urine more acidic, decreasing the rate at which microorganisms can grow and reproduce. Cranberry juice increases the efficiency of urine production by the kidneys. all of the above