Intestinal fructose malabsorption is associated with increased lactulose fermentation in the intestinal lumen.

OBJECTIVE To study fructose malabsorption in children and adolescents with abdominal pain associated with functional gastrointestinal disorders. As an additional objective, the association between intestinal fructose malabsorption and food intake, including the estimated fructose consumption, weight, height, and lactulose fermentability were also studied. METHODS The study included 31 patients with abdominal pain (11 with functional dyspepsia, 10 with irritable bowel syndrome, and 10 with functional abdominal pain). The hydrogen breath test was used to investigate fructose malabsorption and lactulose fermentation in the intestinal lumen. Food consumption was assessed by food registry. Weight and height were measured. RESULTS Fructose malabsorption was characterized in 21 (67.7%) patients (nine with irritable bowel syndrome, seven with functional abdominal pain, and five with functional dyspepsia). Intolerance after fructose administration was observed in six (28.6%) of the 21 patients with fructose malabsorption. Fructose malabsorption was associated with higher (p<0.05) hydrogen production after lactulose ingestion, higher (p<0.05) energy and carbohydrate consumption, and higher (p<0.05) body mass index z-score value for age. Median estimates of daily fructose intake by patients with and without fructose malabsorption were, respectively, 16.1 and 10.5g/day (p=0.087). CONCLUSION Fructose malabsorption is associated with increased lactulose fermentability in the intestinal lumen. Body mass index was higher in patients with fructose malabsorption.