Fructose malabsorption associated with functional abdominal bloating: Case-control study

Abdominal bloating is a common symptom in patients with functional gastrointestinal disorders (FGIDs). The pathophysiology of bloating remains poorly understood. Fructose malabsorption (FM) has been implicated in the pathogenesis of various FGIDs. However, there is limited data on the role of FM in patients with functional abdominal bloating.

To investigate the prevalence and predictors of FM in patients with functional bloating.

This case-control study included 70 patients with functional bloating who met the Rome III criteria and 35 healthy controls. All participants were initially tested for small intestinal bacterial overgrowth, and those who tested negative subsequently underwent a fructose hydrogen breath test (FHBT) to evaluate FM. Breath hydrogen and methane levels were measured at baseline and every 15 minutes for 3 hours. A rise in breath hydrogen or methane levels > 20 ppm above baseline was considered positive. Symptoms were recorded during the test.

FM was detected in 20/70 (29%) patients with functional bloating, compared with 1/35 (3%) in healthy controls (P = 0.01). 51/105 (48%) participants had symptoms during the test, and subjects with positive FHBT had a significantly higher prevalence of symptoms than those with negative FHBT (76% vs 42%; P < 0.01). A subset of patients with functional bloating who tested negative for FHBT had symptoms during FHBT, suggesting a mechanism beyond FM, such as visceral hypersensitivity, in the pathogenesis of functional bloating (80% vs 62%; P = 0.14). Female sex was an independent predictor of FM in the multivariate analysis (P = 0.02). Methane producers were present in 32/70 (46%) patients.

More than one-fourth of patients with functional bloating had FM. Future multicentre prospective studies should evaluate the role of fructose-restricted diets in managing functional bloating.