Altered gut microbiota is increasingly seen as a potential factor in irritable bowel syndrome (IBS) pathophysiology. Human milk oligosaccharides (HMOs) have been shown in healthy adults to increase the abundance of bifidobacteria, which are reported to be depleted in IBS. HMOs may also have beneficial impact on gut motility and visceral pain. We conducted a multi-center, open label trial in patients with IBS (Rome IV criteria plus physician diagnosis) to assess the potential for HMOs to support normal bowel habits and improve other bowel symptoms of IBS.
Subjects were recruited from 17 sites across the United States. The subjects took 5 grams of the HMOs 2'fucosyllactose (2'FL) and lacto-N-neotetraose (LNnT) in a 4:1 mix daily by mouth for 12 weeks. Bowel habits, IBS symptoms and quality of life were assessed at baseline and every 4 weeks during the intervention. Results were analyzed with Intention-to-Treat (ITT) methodology (last observation carried forward for non-completers), using repeated measures Analysis of Variance.
A total of 317 subjects (70.7% females; mean age 44.0 years, range 18-93 years) received the study product; 136 with constipation predominant, 85 with diarrhea predominant, 95 with mixed, and 1 with unspecified IBS. The full 12-week intervention was completed by 245 subjects. In the ITT analyses, the subjects showed a significant reduction from baseline to 12 weeks in total percentage of abnormal bowel movements (Bristol Stool Form Scale types 1, 2, 6, or 7), overall IBS Symptom Severity Score, abdominal pain severity and bloating severity, as well as improvement in health-related quality of life (see Table 1 and Figures 1 and 2). Most of the symptom improvement occurred in the first 4 weeks of intervention. Younger age was predictive of greater improvement in stool consistency and abdominal pain severity. The study product was well tolerated by most patients. The only common side effects were mild GI symptoms such as abdominal discomfort, distension and flatulence.
Our findings suggest that oral supplementation with 2'FL and LNnT can provide nutritional support that significantly reduces abnormal stool consistency, abdominal pain and bloating and improves health-related quality of life in IBS sufferers of all subtypes. However, the results from this open label trial need to be followed up by a randomized controlled trial.