Oral Supplementation of 2'-Fucosyllactose in Allogeneic Bone Marrow Transplant Recipients

High dose chemotherapy and radiation used as preparative regimens in patients undergoing an allogeneic hematopoietic stem cell transplant (HSCT) disrupts intestinal homeostasis by damaging the intestinal epithelium and altering the intestinal microbiome. The investigators hypothesize that 2'-fucosyllactose (2FL) supplementation will be safe and tolerable and result in an increase in the relative abundance of intestinal Bifidobacteria. The investigators also hypothesize that 2FL supplementation will lead to reduction of Firmicutes and/or Proteobacteria, and improved intestinal homeostasis at day+30 as measured by lower pro-inflammatory cytokines, reduced levels of T-cell activation, lower markers of intestinal injury (fecal human DNA and plasma reg-3-alpha), increased fecal butyrate levels and ultimately lower incidence of acute GVHD and BSI at day+100. Phase II: The investigators hypothesize that 2FL supplementation will be safe and tolerable and result in an increase in the relative abundance of fecal short chain fatty acids such as butyrate, acetate and propionate at day+7 compared to baseline values.

Inclusion Criteria: * Be scheduled for allogeneic stem cell transplant * All ages and underlying diagnoses, preparative regimens, stem cell sources and acute GVHD prophylaxes Exclusion Criteria: * Unable to take anything orally or enterally (i.e. intestinal failure) * Actively breastfeeding infants * Recent (within the week prior to enrollment) GI infection * Patients receiving anti-diarrheal medications such as loperamide * Patients who have received probiotics or prebiotics during the previous month * Patients who have had any type of gut damage within the past 3 months such as previous bowel perforations, previous episode of Grade 4 neutropenic colitis or typhlitis * Patients with inflammatory bowel disease, short bowel syndrome, and patients with a history of bowel resections