Effects of Synbiotic Supplementation on Gastrointestinal Symptoms, Appetite, and Nutritional Recovery in Patients After Autologous Bone Marrow Transplant

Patients undergoing autologous bone marrow transplantation (ABMT) receive high-dose chemotherapy and routine prophylactic antibiotics, which often disrupt the gut microbiome (dysbiosis). This imbalance can lead to debilitating gastrointestinal complications, loss of appetite, decreased dietary intake, and malnutrition, impairing recovery. The purpose of this randomized controlled trial is to evaluate whether daily supplementation with a tri-component synbiotic (combining multispecies probiotics, xylo-oligosaccharide prebiotics, and a tributyrin postbiotic) can improve gastrointestinal symptoms, appetite, and nutritional status in adult hematological cancer patients following autologous bone marrow transplantation. Participants will be randomly assigned (1:1 ratio) to either: 1. Control Group: Receiving standard post-transplant nutritional care based on clinical guidelines. 2. Intervention Group: Receiving the same standard nutritional care plus a daily oral synbiotic capsule for 3 months. Participants will be followed during the 3-month intervention period and for an additional 1-month post-intervention follow-up phase to assess the sustainability of benefits. The study will evaluate digestive symptoms, self-reported appetite, dietary intake, body weight, inflammatory markers (fecal calprotectin), and protein status (serum albumin), while closely monitoring participant safety.

Inclusion Criteria: * Adult patients aged 20 to 65 years with hematological malignancies. * Having undergone successful autologous bone marrow transplantation with confirmed neutrophil and platelet engraftment on day 30 post-transplant. * Hematologically stable, clinically defined and laboratory-confirmed on day 30 post-transplant by: * Neutrophil engraftment: Absolute Neutrophil Count (ANC) \>= 1,500/mcL (or \>= 1.5 x 10\^9/L) maintained for at least 3 consecutive days without hematopoietic growth factor support. * Platelet engraftment: Platelet count \>= 20,000/mcL (or \>= 50,000/mcL according to institutional safety protocols) sustained without platelet transfusion for at least 7 consecutive days. * Hemoglobin stability: Hemoglobin level \>= 8.0 g/dL without active bleeding or acute transfusion requirement. * Discharged from the hospital and capable of oral intake and adherence to the daily supplement regimen. * Capable of providing written informed consent. Exclusion Criteria: * Pre-existing severe gastrointestinal disorders (e.g., inflammatory bowel disease, active enteritis, or history of colorectal surgery/resection). * Severe renal or hepatic impairment (e.g., pre-existing documented history or established clinical diagnosis of advanced renal failure, active requirement for renal replacement therapy, or decompensated liver disease, verified directly from institutional medical records). * Active, prolonged high-dose systemic corticosteroid therapy or uncontrolled diabetes mellitus that may independently alter gastrointestinal motility, mucosal integrity, or appetite regulation. * Known allergies or hypersensitivity to any component of the synbiotic formulation. * Current or regular use of other commercial probiotic, prebiotic, or synbiotic supplements within 30 days prior to enrollment.