Study participants
diarrhea, constipation
The study participants were 70 students enrolled at the Yamagata Prefectural Yonezawa University of Nutrition Sciences or Sakura no Seibo Junior College. Two participants who had taken medications for diarrhea or constipation during the week before fecal sampling were excluded from the analysis. Additionally, during cluster analysis, we excluded a third participant who did not fit any cluster. Therefore, 67 participants were included in the analysis (5 males, 62 females; age: 18–22). All participants provided written informed consent; the study protocol was approved by the Ethics Committee of the Yamagata Prefectural Yonezawa University of Nutrition Sciences (Approval No. 2019–9), and the study protocol was according to the Declaration of Helsinki.