The study included 40 female patients (age 26-87 years; 62.3 ± 2.1 [mean ± standard error]) with PBS/IC in stable condition (duration of disease: 1.9-9.0 years; 5.3 ± 0.3).
In cooperation with the nutrition control team, we developed an original PBS/IC diet (1,500 kcal, 65 g protein, 40 g fat, 220 g carbohydrate, 1,000 ml water, 7 g salt). Data regarding daily food intake and food-related symptoms were collected by conducting a detailed interview of each patient, and we set meal menu to control PBS/IC symptoms and advised
the patients to reduce the intake of specific food items to the maximum possible extent. The following food items were removed from or restricted in the diet of patients: tomatoes, tomato products, soybean, tofu product, spices, excessive potassium, citrus, high-acidity-inducing substances, etc. We randomly assigned 30 patients to group A with instructions to follow this diet for 1.5 years (intensive systematic dietary manipulation: ISDM), and 10 patients to group B without instructions (non-intensive dietary manipulation: NIDM). We prospectively studied changes in the O’Leary-Sant Symptom Index and Problem Index (OSSI/OSPI), urinary urgency visual analog scale (VAS) score (U: 0, no urgency; 9, severe urgency), bladder/pelvic pain VAS score (P: 0, no pain; 9, worst possible pain), and quality of life (QOL: 0, very satisfied; 6, very unsatisfied) from before the start of treatment to 1.5 years after treatment. The clinical research was started after obtaining the approval from the ethics committee of our hospital. A written informed consent form was obtained from the patients after a full explanation of the purposes and procedures of the study. Statistical analysis was performed by using a t test. The significance level was set at P <.05.