Effect of cranberry juice on urinary pH.

Twenty-one female and 19 male subjects who had normal physical and laboratory examinations were randomly assigned into four groups of 10 subjects each. Each group was then randomly assigned a number (150, 180, 210, 240) which determined the amount of cranberry juice, in milliliters, members of that group would ingest with each meal during the experimental phase of the study. The study took place over a 12-day period. A one-group before-and-after design was used, with each subject serving as his or her own control. Diet was controlled; menus on days 1 through 6 were repeated on days 7 through 12 with the addition of cranberry juice at each meal. Subjects used nitrazine pH tape to measure the pH of midstream urine at each voiding. There were significant (.01 level) differences in mean urinary pH between each control group and its corresponding experimental group. Anticipated problems with increased number of bowel movements, weight gain, increased voiding frequency, and subject pH measurement inaccuracy did not occur.