Prebiotics, the gastrointestinal microbiome and clinical outcomes post allogeneic stem cell transplantation

This study aims to compare enteral feed tolerance, microbial diversity, microbiome composition and clinical outcomes between patients who receive standard non fibre enteral nutrition (EN) vs prebiotic containing EN post allogeneic stem cell transplantation. Patients will be allocated to standard or prebiotic EN consecutively (first 10 patients recruited will be allocated to standard care, last 20 patients to intervention). Nutrition support is provided while participants are inpatients for stem cell transplantation. Conditioning pre transplant will be as per usual care, for 5-12 days depending on regimen. Participants in both groups will commence EN, increase the feeding rate and cease feeding as per usual care. This includes commencing EN on day +1 post transplant at 30ml/hr of continuous feeding via a 10-12fr nasogastric tube, increasing to 50ml/hr when oral intake declines to <50% of meals and increasing to goal EN (providing 100% of estimated requirements) if oral intake is minimal. If EN ceases due to intolerance and oral intake is poor, patients will be converted to parenteral nutrition (PN). Both EN and PN will cease once oral intake is >50% meals and 2 high protein drinks/ day post neutrophil engraftment. During provision of nutrition support patients will be provided with high protein high energy meals and snacks and encouraged to continue oral intake if tolerated. Participants allocated to receive the prebiotic EN will receive a polymeric ready to hang formula (1.2kcal/ml, 63g protein,15g fibre /L) containing inulin, oligofructose, arabic gum, soy polysaccharides, cellulose and resistant starch, instead of the usual non fibre EN formula. Tolerance of EN will be monitored and if poor, participants will be changed to PN as per standard care. Adherance to the intervention is monitored by review of the participants fluid balance charts and documenting the amount of prescribed feed actually received. Stool samples will be collected pre conditioning, post conditioning and at day 12-18 post transplant (peri engraftment). Blood samples will be collected post conditioning and at two weeks post transplant. Clinical outcomes will be collected during the transplant admission and at day 100. Oral intake will be monitored for three days pre conditioning (participants will complete a paper food diary or record intake in the 'Easy diet diary' app) and for two weeks post transplant while inpatients (paper diary).