2.1. Clinical Study Design
allergies, Defecation, volume of defecation, chronic disease
DISEASE, ALLERGIES, CHRONIC DISEASE
We conducted a randomized, double-blind, placebo-controlled study of children attending one of two kindergartens in Chiba City from September 2021 to December 2021. The kindergartners themselves and their parents were asked about their willingness to participate in the study, and those who expressed a willingness to participate were asked to complete a preliminary survey. In the pre-survey, participants record their bowel movements for one week. Inclusion criteria were kindergartners who reported defecation on ≤4 days per week in the pre-survey. Exclusion criteria were (1) those with a chronic disease or a history of serious disease, (2) those with allergies to the study foods, and (3) those who planned to start or finish taking prebiotic or probiotic preparations or foods during the study period. Eligible subjects were randomly assigned to either a kestose or a maltose group. The allocation factor was facility (per kindergarten), with stratified randomization and assignment to two groups. The allocation was performed by a different person than the one conducting the study and data analysis. Because this was a pilot study to estimate the effect of kestose on constipated infants, no effect size was obtained a priori. Therefore, the number of cases was designed based on feasibility.Participants consumed 3 g of kestose (Kestose 95; B Food Science Co., Aichi, Japan) or 3 g of maltose (Sunmalt; Hayashibara Co., Okayama, Japan) once a day for 8 weeks. Maltose was chosen as a placebo with no significant effect on the gut microbiota. Daily defecation was recorded for 16 weeks, and the frequency of defecation, volume of defecation, fecal characteristics, and color of feces were investigated. Defecation volume was visually assessed as the approximate equivalent of the number of chicken eggs (ranging from 1/4 to 10 eggs). Stool characteristics were rated on a 7-point Bristol scale [Stool samples were also collected from participants on the start date and after 8 weeks and 16 weeks of test-food consumption. Samples were temporarily stored at −20 °C, then at −80 °C until used for analysis.The test schedule is shown in 