Fructose Malabsorption and Lactose Maldigestion in Patients with Irritable Bowel Syndrome and Other GI Conditions

Abstract

Purpose: Carbohydrates may play a role in symptoms experienced by patients with irritable bowel syndrome (IBS) and those with other functional or undiagnosed abdominal conditions. The purpose of this study was to determine the prevalence of fructose malabsorption (FM) and lactose maldigestion (LM) in a cohort of patients who did and did not meet Rome I and II criteria for IBS. Methods: The study group consisted of patients who were evauated for IBS, diarrhea, abdominal discomfort, bloating or other symptoms attributable to the hollow viscus. A questionnaire was completed noting demographics, Rome I and II IBS symptom criteria and exclusions. Study subjects had breath collections before and after lactose challenge with 50g powdered lactose in water and on a separate day 1 week apart challenge with fructose 25g. Breath samples were analyzed for hydrogen, methane and CO2 (for correction) using a Quintron MicroLyer model SC. FM and LM were defined by a greater than 20ppm gas rise above fasting baseline. Results: Of the 66 subjects (72% of the study cohort) who met IBS criteria, there were 54 females and 12 males. The mean age of the IBS group was 47 years ± 14. Nine (14%) had FM and 26 (39%) had LM. Of those who did not meet IBS criteria, there were 19 females and 7 males. The mean age was 56 ± 12. Three (11%) had FM and nine (34%) had LM. No symptom or demographic predicted carbohydrate challenge results. Conclusions: The prevalence of FM and LM are such that carbohydrate testing is advised for those with IBS and other functional and undiagnosed gastrointestinal conditions. Further experience and investigation will be needed to elucidate the clinical importance of FM and LM in these disorders.