Randomized evaluation of gastrointestinal tolerance to high daily intake of short-chain fructo-oligosaccharides in school-aged children.

Dietary fiber intake in children remains below recommendations, and short-chain fructo-oligosaccharides (scFOS) prebiotic fibers may help close this gap. This clinical trial assessed gastrointestinal tolerance to two substantial scFOS doses in healthy school-aged children with low fiber intake. In a randomized parallel-group design, 78 children aged 6-12 y consumed 10 or 20 g/d scFOS (Actilight®) for 7 d following a 7-d baseline period. Gastrointestinal symptoms were recorded daily using a 4-point Likert scale (0: none; 3: severe). Stool frequency and consistency (Bristol Stool Scale) and well-being scores were also assessed. Analyses considered age (6-9 vs. 10-12 y) and sex. Flatulence mean scores slightly increased at both doses (+0.23 at 10 g/d; +0.31 at 20 g/d; P < 0.001), and abdominal discomfort rose with 20 g/d (+0.19 in week 2 vs. week 1; P < 0.001), while remaining mild. All other symptoms stayed <1 (mild). Stool frequency enhanced at 20 g/d (+1.19; P < 0.05), keeping within normal limits. Stool consistency increased in both groups (+0.2 and +0.71; P < 0.05), with a dose-dependent shift toward softer stools but remaining in the expected range (types 3-4). However, 12.8% of children were more sensitive to 20 g/d with declared diarrhea. Overall well-being remained high (>8/10), and no serious adverse events occurred. In conclusion, scFOS up to 20 g/d is well tolerated in children, supporting its use to enhance fiber intake. While generally mild, effects at 20 g/d in a small sensitive subgroup highlight inter-individual variability and support gradual introduction to improve tolerance.