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Title: The impact of dietary interventions for irritable bowel syndrome on the gastrointestinal microbiota, symptoms, nutrient intake and quality of life
Author: Staudacher, Heidi Maria
ISNI:       0000 0004 5917 8938
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2016
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Irritable bowel syndrome (IBS) is a common functional bowel disorder characterised by abdominal pain or discomfort and altered bowel habit. It negatively influences quality of life and poses a considerable economic burden to patients, healthcare resources and society. Treatments are symptom-directed but the complex pathophysiology of the condition, and the heterogeneity and instability of presenting symptoms lead to treatment challenges. Many patients with IBS have attempted and/or seek information about dietary approaches to manage their symptoms. One issue that has limited obtaining robust research evidence for dietary advice interventions in IBS is the difficulty of implementing a suitable placebo control. Previous studies have utilised standard IBS dietary advice or habitual diet as the placebo comparator intervention, or have been feeding studies, all of which have their limitations. Therefore, a novel sham diet was designed, developed and evaluated for use as a placebo control in a dietary advice RCT. There is growing evidence for the clinical effectiveness of the low FODMAP diet in IBS, however a blinded, placebo-controlled, dietary advice RCT had never been performed. Furthermore, whether the acute effect of the low FODMAP diet on the GI microbiota could be prevented required investigation. Therefore a 2x2 factorial design blinded placebo-controlled RCT was conducted in 104 patients. More patients in the low FODMAP diet group reported a clinically important reduction in IBS-SSS score compared with the sham diet group (73% vs 42%, p=0.005). There was also a lower abundance of stool Bifidobacteria in the low FODMAP diet group compared with sham (8.8 vs 9.0 log10 cells/g faeces, p=0.028). Probiotic co-administration with VSL#3 ameliorated the effect of the low FODMAP diet on Bifidobacteria, and as a sole intervention increased Bifidobacteria abundance compared with placebo but did not have a convincing effect on GI symptoms. In conclusion, there is compelling evidence for the beneficial effect of the low FODMAP diet in a majority of patients with IBS. The ramifications of this diet both on the GI microbiota and on nutrient intake confirm the importance of FODMAP reintroduction to tolerance, and that the diet is dietitian-led. Probiotic ameliorated the effect of low FODMAP diet-induced microbiota aberration, however the degree of recovery in response to FODMAP reintroduction requires evaluation before probiotic co-administration is recommended as routine practice.
Supervisor: academic, affiliated ; Whelan, Kevin Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available