Prebiotics mitigate mucosal injury. (A) The proportion of combined RS and GFO and RS and GFO prebiotic intake during the study period. (B) The absolute amount of consumed dietary fiber derived from the combined and separate RS and GFO prebiotics. The horizontal lines represent median values. (C) Oral mucositis was assessed from day 0 to engraftment according to the OAG score. No significant difference between the maximum OAG scores in the historical control and prebiotics groups was observed (median, 13 vs 14; P = .101). The duration of moderate or severe (ie, OAG score ≥12) oral mucositis in the prebiotics group was significantly shorter than that in the historical control group (median, 11 d vs 14 days; P < .001). (D) Prebiotics reduce the severity of oral mucositis early after allo-HSCT. OAG score from allo-HSCT (day 0) to neutrophil engraftment. Average OAG scores in the 2 groups are depicted. The OAG scores in the prebiotics group were significantly lower than those in the historical control group from days 0 to 9 (*P < .05). (E-F) Diarrhea from day 0 to engraftment was assessed using CTCAE v4.0. (E) The maximum grade of diarrhea was assessed in both groups. The ratio of grade 0 diarrhea was higher in the prebiotics group than in the historical control group (17% and 7%, respectively), although the difference between the groups in the ratio of maximum grade of diarrhea was not significant (P = .260; Fisher’s exact test). (F) The duration of diarrhea in the prebiotics group was significantly shorter than that in the historical control group (median, 7 days vs 9 days; P = .049).