Lactulose, Lactose and Fructose Ingestion Induces Specific Patterns of Gastrointestinal Symptoms in Chinese Subjects with Functional Dyspepsia and Irritable Bowel Symptoms

Abstract

Background: Prevalence rates of Functional Dyspepsia (FD) in East Asia are three times higher than Irritable Bowel Syndrome (IBS) rates. Many researchers have suggested that IBS subjects in the region experience their pain and discomfort in the upper abdomen, leading to misdiagnosis as FD. Aim: To compare patterns of gastrointestinal (GI) symptom genesis in the Chinese population with IBS or FD during provocative hydrogen breath testing (HBT) with lactulose, lactose and fructose . Methods: Subjects fulfilling the ROME III classification of FD and IBS and control subjects with no known GI disorder/symptoms were recruited. All subjects underwent HBT +/- methane assessment with lactulose (10 ml), lactose (25 g) and fructose (25 g). Subsequent breath tests were performed after a washout period of at least one week. Breath tests were performed after an overnight fast, with the patient sedentary. Breath samples taken every 15 minutes for 3 h. GI symptoms were recorded during these 3 h and at a telephone follow up 24 hours later. Results: A total of 353 subjects completed at least one breath test examination and 307 subjects completed all three breath tests. 16%, 55% and 29% were control, functional dyspepsia, irritable bowel syndrome subjects. All study subjects were ethnic Chinese, the mean age was 53 [Range; 18-76) y and 31% [95% CI; 26-35%] were male. 85% [95% CI; 84-91%] of subjects were hydrogen-producers and 100% methane-producers. Symptoms were induced in a low proportion of healthy controls. Both FD and IBS subjects experienced similar proportions of epigastric pain on consumption of lactulose, lactose and fructose. See Table 1. Subjects with FD experience more belching than subjects with IBS when lactulose [58 vs. 42%, p = 0.011] and lactose [62 vs. 46%, p =0.014] were ingested, respectively. Subjects with IBS experience significantly more “lower GI” symptoms of abdominal pain and development of loose stools when lactulose was ingested when compared with subjects with FD. In general subjects with IBS experienced both epigastric pain and abdominal pain when any of the three carbohydrate solutions were ingested. Conclusion: Chinese subjects commonly co-produced hydrogen and methane. Ingestion of poorly absorbed sugars induces symptom patterns in patients with FD in similar proportions. Chinese IBS subjects commonly experiencing epigastric and abdominal pain. Reducing poorly absorbed short-chain carbohydrates (FODMAPs) might be efficacious in FD as it is in IBS.