Dietary fiber in pediatric gastrointestinal health: a narrative review of evidence and challenges

Dietary fiber plays a central role in pediatric gastrointestinal health; however, most children worldwide consume amounts well below recommended levels. Current pediatric guidelines from the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (2014) and global nutrition guidance from the World Health Organization recommend adequate dietary fiber intake as part of a balanced diet to support digestive health and prevent noncommunicable diseases. These recommendations generally correspond to daily fiber intake levels of approximately 14-31 g/day, or the practical rule of age (years) + 5 g/day for children, yet more than 80%-90% of children fail to meet these targets. This shortfall is clinically significant, as inadequate fiber intake is associated with increased risk of functional constipation, a condition affecting approximately 3%-29% of children globally. Dietary fiber contributes not only to stool bulk but also to the modulation of gut microbiota, gastrointestinal barrier function, and immune and metabolic pathways during critical developmental stages. Among common pediatric gastrointestinal disorders, the strongest evidence supports fiber use in constipation management, where supplementation or increased intake through whole foods has been shown to improve stool frequency and consistency in approximately 50%-60% of affected children. However, clinical trial outcomes remain inconsistent, varying according to fiber type, dosage, duration of intervention, and diagnostic criteria. Evidence for recurrent or functional abdominal pain remains limited and heterogeneous, with small sample sizes, differing endpoints, and high placebo response rates complicating interpretation. In pediatric inflammatory bowel disease, fermentable fibers have been shown to enhance short-chain fatty acid production. Nevertheless, robust pediatric clinical evidence remains insufficient, and findings from adult ulcerative colitis studies cannot be directly extrapolated to children. Dietary fiber represents an important supportive component of pediatric gastrointestinal management, but standardized dosing recommendations and high-quality pediatric clinical trials are still needed to establish evidence-based guidelines for clinical practice.