The Adult Carbohydrate Perception Questionnaire Identifies Patients with Lactose or Fructose Intolerance Who Respond to Diet.

Introduction: There is no evidence that a positive breath test is a good predictor of the success of a carbohydrate-restricted diet. Our objective was to investigate whether patients in whom lactose intolerance (LIT) or fructose intolerance (FIT) is diagnosed by validated symptom measurement respond to diet.

Methods: Patients referred for evaluation of LIT or FIT underwent hydrogen/methane breath testing (malabsorption test) and symptom measurement with the adult Carbohydrate Perception Questionnaire (aCPQ, intolerance test) before and after 50 g lactose or 25 g fructose. Patients with a positive aCPQ received instructions on specific diets and supplements. Severity of abdominal pain, bloating, diarrhoea, flatulence, and nausea were measured using a visual analogue scale (VAS) before (VAS1, mm) and after (VAS2, mm) diet. The change in VAS for individual symptoms and overall symptoms after diet is expressed as deltaVAS (mm) and as change relative to VAS1 (%).

Results: Forty-one patients were included (23 LIT, 8 FIT, 10 LIT+FIT). Eight patients had negative breath tests (no malabsorption). After 2 months of diet, the overall VAS and the individual symptoms decreased (p < 0.001). Overall VAS1 and the VAS1 for individual symptoms correlated significantly with the decrease in deltaVAS (mm) after diet. Nineteen patients (46%) had total recovery, and additional 13 patients (32%) had improvement of >50%. Response to diet was independent of breath test results.

Conclusion: This uncontrolled and unblinded study suggests that patients with carbohydrate intolerance diagnosed by aCPQ benefit significantly from diet, independent of the presence of malabsorption. Controlled studies are required to confirm these results in larger patient groups.