Efficacy of individualised diets in patients with irritable bowel syndrome: a randomised controlled trial

Abstract

Background: Patients with irritable bowel syndrome (IBS) are often placed on diets guided by food intolerance assays, although these have not been validated. We assessed the effects of individualised diets in patients with IBS guided by a leucocyte activation test.

Methods: This is a parallel-group, double-blind, randomised controlled trial of 58 adults with IBS seen at an academic health centre in Northeast USA. Peripheral venous blood was analysed using a leucocyte activation test; individual foods were reported to produce positive or negative results. Participants were randomised to a 4-week diet with either individualised guidance to eliminate foods with positive assay results and allow foods with negative assay results (intervention), or with individualised guidance, matched in rigour and complexity, to eliminate foods with negative assay results and allow foods with positive assay results (comparison). The primary outcome was between-group differences in the IBS Global Improvement Scale (GIS). Secondary outcomes included reductions in IBS Symptom Severity Scale (SSS) scores and increases in IBS Adequate Relief (AR) and Quality of Life (QOL) scores. An aptamer-based proteomic analysis was conducted in strong responders.

Results: The intervention group had significantly greater increases in mean GIS score after 4 weeks (0.86 vs comparison; 95% CI 0.05 to 1.67; p=0.04) and 8 weeks (1.22 vs comparison; 95% CI 0.22 to 2.22; p=0.02). The intervention group also had significantly greater reductions in mean SSS score at 4 weeks (-61.78 vs comparison; 95% CI -4.43 to -119.14; p=0.04) and 8 weeks (-66.42 vs comparison; 95% CI -5.75 to -127.09; p=0.03). There were no significant differences between intervention and comparison groups in mean AR or QOL scores. A reduction in neutrophil elastase concentration was associated with reduced symptoms.

Conclusions: Elimination diets guided by leucocyte activation tests reduced symptoms. These findings could lead to insights into the pathophysiology of IBS.

Trial registration number: NCT02186743.

Keywords: Dietary Factors; Irritable Bowel Syndrome; Quality Of Life.

Figure 1

CONSORT flow diagram.

Figure 2

Change from baseline in global improvement, symptom severity, adequate relief, and quality of life. IBS-GIS indicates the Irritable Bowel Syndrome Global Improvement Scale; IBS-SSS, Irritable Bowel Syndrome Symptom Severity Scale; IBS-AR, Irritable Bowel Syndrome Adequate Relief; and IBS-QOL, Irritable Bowel Syndrome Quality of Life Questionnaire. Values are expressed as mean change. Positive scores denote improvement. The intervention group demonstrated significantly larger between-group improvement than the comparison group in the (A) GIS at 4 weeks (1.93 vs 1.07; ES 0.55, p=0.04; n=56—primary endpoint) and 8 weeks postbaseline (1.81 vs 0.59; ES 0.63, p=0.02; n=55), and (B) SSS at 4 weeks (121.4 vs 59.6; ES 0.56, p=0.04) and 8 weeks (116.4 vs 50.0; Effect Size (Cohen's D) (ES) 0.57, p=0.03) postbaseline. No significant between-group differences were seen in the (C) AR and (D) QOL scales. Relative to baseline, all outcomes improved in both groups at 4 weeks and 8 weeks.