2.1. Study Design
MAY, SECONDARY
This was a double-blind, randomized, placebo-controlled, parallel study. Participants were recruited at the Department of Medical Management and Informatics, Hokkaido Information University (Hokkaido, Japan) and randomly allocated 1:1 to each group. The allocation was conducted by a third-party organization using block randomization. The assignment was blinded by participants, researchers, evaluators, and physicians until the investigation was completed. During this study, physical examination, blood sampling, and medical interviews were performed three times: the pretrial test, 0- and 4-week visits. Dietary surveys were conducted at 0- and 4-week visits. Before both 0- and 4-week visits, fecal samples and EEG data were collected. The participants were directed to take five YM/placebo tablets once a day during the intervention. The daily logs included information on bowel movements, tablet intake, menstrual status, physical status, and the use of other medications. The study was conducted from May 2021 to November 2021. The primary outcomes were defined as bowel habits assessed by the daily defecation log, and the secondary outcomes were defined as sleep quality and fecal properties assessed by quantitative PCR and metabolomics based on capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS).