Intestinal Fermentation Assessed by Intraluminal pH in Subjects With Abdominal Bloating

Abstract

Abdominal bloating symptoms are highly prevalent in subjects with functional GI disorders and are associated with increased healthcare utilization and reduced quality of life [APT 2010]. Altered intestinal transit and abnormal intraluminal fermentation have been proposed as possible pathophysiological mechanisms for these symptoms. We have previously demonstrated slower colonic transit in subjects with abdominal bloating compared to subjects without bloating. In this study we investigated the hypothesis that abdominal bloating symptoms are associated with abnormally increased intestinal fermentation.Aim: To investigate and compare the magnitude and site of intestinal fermentation in subjects with functional GI symptoms and bloating (FGI-B) and healthy controls (HC) by measuring pH in the GI lumen. Methods: We studied a total of 47 subjects; FGI-B (n=37) and HC (n=10). Intestinal intraluminal pH was used as a surrogate marker for intestinal fermentation. The intestinal pH levels were measured at different segments of the GI tract using a wireless motility capsule (WMC). Comparisons of transit time and pH variables between the groups were done using t-test; correlation analyses were done using Spearman Correlation Coefficients. Results: Intestinal pH levels were significantly lower at the proximal colon (Q1) of subjects with FGI-B compared to HC (mean pH 6.27 vs. 6.84; p=0.008) suggesting a significantly higher intraluminal intestinal fermentation at this segment of the GI tract in these subjects. The mean intraluminal colonic pH levels in the FGI-B group were also lower than that of HC at other segments of the large intestine; however, statistical differences were noticed only in the proximal and total colon. Mean colonic pH levels at the four (proximal to distal) colonic segments and the total colon are provided in the following Table. There were no noticeable differences between the groups in mean pH levels at any of the segments of the small bowel. The average total colonic pH significantly correlated with the total colonic transit time (r=0.34; p=0.014). However, no correlation was found between the average small bowel pH and small bowel transit time.Conclusions: We provide evidence of abnormal intestinal fermentation in subjects with functional GI symptoms and bloating. We demonstrate that bloating symptoms are associated with increased fermentation in the large rather than the small bowel. WMCmay be helpful in identifying underlying physiological abnormalities and guide treatment in patients with bloating symptoms. Mean intraluminal pH levels in subjects with abdominal bloating and healthy controls