Short bowel syndrome (SBS) is a rare but challenging condition in which patients have insufficient bowel length to meet fluid, electrolyte, and nutrient requirements without parenteral support.

The purpose of this study is to determine how well dietary fiber is tolerated in patients with short bowel syndrome compared to patients without short bowel syndrome based on assessment of gastrointestinal symptoms, and corresponding changes in microbiome composition and metabolomics.

Short bowel syndrome (SBS) is a rare but challenging condition in which patients have insufficient bowel length to meet fluid, electrolyte, and nutrient requirements without parenteral support. The goal of SBS treatment is to achieve enteral autonomy using strategies that optimize intestinal absorption while minimizing unpleasant gastrointestinal (GI) side effects. One strategy that has emerged is the addition of soluble fiber to enteral formula, and this strategy has gained popularity in clinical practice as fiber-rich formulas comprised of blenderized whole foods have become commercially available. However, the investigators' preliminary observations suggest that patients with SBS have variable tolerance and growth outcomes on these blenderized feeds. To date, there are no clinical studies documenting the effects of dietary fiber in SBS patients and guidance in enteral nutrition advancement is lacking in this medically complex population. The current study aims to explore the tolerance of controlled fiber addition to enteral formula based on assessment of GI symptoms, and corresponding changes in microbiome composition, and metabolomics in pediatric patients with SBS versus non-SBS controls. The investigators will use a practical approach with fiber introduction and slowly advance to goal fiber intake to understand the factors leading to continuation. Stool, urine, and plasma samples collected pre- and post- intervention will help identify biomarkers that would predict successful fiber tolerance and optimize selection of patients for fiber introduction. While there is no intent to treat, mitigate, prevent, diagnose or cure the symptoms of SBS, the study may help shed light on the underlying mechanism for intolerance to dietary fiber.

Inclusion Criteria:

• Actively follows at the Children's Hospital of Philadelphia (CHOP) outpatient clinics
• SBS arm specific: History of SBS diagnosis. History of short bowel syndrome based on surgical/imaging records. Small bowel is in continuity with some portion of colon
• Control arm specific: No history of intestinal pathologies
• No or negligible amount (few bites of fiber-containing foods okay) of fiber in tube feeds or by mouth at baseline
• Less than 20% calories from oral food not containing fiber while the other 80% may be by enteral and/or parenteral feedings
• At least 20% calories from fiber-free formula taken orally or via tube
• Antibiotic use is allowed, however, should be on a stable regimen of antibiotics starting from 2 weeks prior to intervention until end of study or end of week 3 whichever is sooner. Instances of antibiotic use for brief courses (7-10 days) as long as sample collection is scheduled to be at least a week from the end date of antibiotics.
• Previous history of fiber introduction failure is acceptable as long as clinically stable at the time of recruitment
• Fiber supplementation is appropriate per primary physician
• If subject is unable to provide full set of samples, they will still be enrolled

Exclusion Criteria:

• SBS Arm specific: No diagnosis of SBS.
• Control Arm specific: has baseline intestinal diseases
• Small bowel and colon not in continuity (Ex: presence of ileostomy or jejunostomy)
• >5% changes in percentage of calories from oral nutrition (PO), enteral nutrition (EN) and/or parenteral nutrition (PN) during the intervention
• Addition/discontinuation/significant alteration to antibiotics regimen during study period
• Primary physician does not think fiber supplementation is appropriate clinically