Predicting responses of patients with IBS to low-FODMAP diet and probiotics

This month's publication of Clinical Gastroenterology and Hepatology examines how volatile organic compounds in feces associate with response to dietary intervention in patients with irritable bowel syndrome.

Dietary interventions are effective in management of patients with irritable bowel syndrome, although responses vary.

Dr Kevin Whelan and colleagues from the United Kingdom investigated whether fecal levels of volatile organic compounds associate with response to dietary interventions in patients with irritable bowel syndrome.

Adults who fulfilled the Rome III criteria for irritable bowel syndrome were recruited to a 2x2 factorial randomized controlled trial.

Patients were randomly assigned to a group counselled to follow a diet low in fructans, galacto-oligosaccharides, lactose, fructose, and polyols or a group that received placebo dietary advice for 4 weeks.

Patients from each group were also given either a multi-strain probiotic or placebo supplement.

Response was defined as a reduction of 50 points or more on the validated irritable bowel syndrome symptom scoring system.

The researchers collected fecal samples from participants at baseline and end of the 4-week study period, and volatile organic compounds were analyzed by a gas-chromatography sensor device.

The team determined volatile organic compounds profiles using a pipeline involving wavelet transformation followed by feature selection based on random forest.

Volatile organic compounds profiles contained 15 features that classified response to the low-FODMAP diet with a mean accuracy of 97%

Clinical Gastroenterology and Hepatology

A partial least squares classifier was constructed to classify volatile organic compounds profiles by response and accuracies were determined using 10-fold cross-validation.

Data from 93 patients who completed the study were used in the final analysis.

The team found more patients responded to the low-FODMAP diet than the sham diet, but there was no difference in response between patients given the probiotic vs the placebo, with no interaction between the diet and supplement interventions.

At baseline, volatile organic compounds profiles contained 15 features that classified response to the low-FODMAP diet with a mean accuracy of 97% and 10 features that classified response to probiotic with a mean accuracy of 89%.

End of treatment models achieved similar predictive powers and accuracies.

Dr Whelan's team comments, "Fecal volatile organic compounds profiling is a low cost, non-invasive tool that might be used to predict responses of patients with irritable bowel syndrome to low-FODMAP diet and probiotics and identify their mechanisms of action."