A Very Low Carbohydrate Diet Provides Adequate Relief of Symptoms and Improves Quality of Life in Overweight and Obese Individuals with Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D)

Abstract

Purpose: Patients with irritable bowel syndrome (IBS) frequently identify worsening of symptoms after meals, citing certain foods including increased carbohydrates as triggers of their symptoms, particularly among those with diarrhea-predominant IBS (IBS-D). Patients with IBS-D anecdotally report improvement in symptoms after initiating a very low carbohydrate diet (VLCD), but no study has investigated the effect of a VLCD in IBS-D. The purpose of this study is to determine the effect of a VLCD in overweight and obese individuals with IBS-D. Methods: Eligible participants were those with a body mass index > 25 kg/m2 who met Rome II criteria for IBS-D and had at least moderately severe IBS, as defined by a score of > 36 on the Functional Bowel Disorder Severity Index. Participants were provided a standard diet for 2 weeks, followed by a VLCD (20 grams of carbohydrates/day) for 4 weeks. The primary outcome was adequate relief (AR), as assessed by a weekly one-item questionnaire during the 4 weeks of the VLCD. A responder was a participant who reported AR of all GI symptoms in at least 2 of the 4 weeks during the VLCD. Using daily diary cards for all 6 weeks, participants recorded daily stool frequency, stool consistency using the Bristol Stool Scale (BSS) that ranges from 1 (hard/lumpy) to 7 (watery), and abdominal pain using a visual analog scale (VAS, scale of 0–100). Participants also recorded AR daily during the VLCD. The IBS Quality of Life (IBS-QOL) and Sickness Impact Profile (SIP) questionnaires were administered before and after the 4-week VLCD trial. Results: A total of 17 individuals were enrolled: 1 dropped out during Week 1 of the study (intolerance of standard diet), 3 dropped out during Week 3 of the study (2 due to intolerance of the VLCD and 1 due to emotional symptoms), and 13 completed all 6 weeks. During the VLCD, all 13 participants met the responder definition and also had AR at week 4 of the VLCD. Furthermore, 10/13 participants reported AR for all 4 weeks of the VLCD, and AR for at least 90% of the days during the VLCD. Stool frequency decreased from a mean (±SD) of 2.6 ± 0.8/day to 1.4 ± 0.6/day (P < 0.001) and stool consistency improved on BSS from 5.3 ± 0.7 to 3.8 ± 1.2 (P < 0.001). Pain scores (VAS) decreased from 26 ± 18 to 10 ± 10 (P= 0.007). Both the IBS-QOL (71 ± 22 to 81 ± 13; P= 0.02) and the SIP (5.5 ± 6.4 to 2.3 ± 3.6; P= 0.001) showed clinically meaningful improvement. Finally, although participants lost an average of 3.1 ± 1.7 kg (P < 0.0001), clinical improvement was independent of weight loss. Conclusion: In this open label study, initiation of a VLCD in overweight and obese individuals with IBS-D for 4 weeks provides adequate relief, decreases abdominal pain, improves stool frequency and consistency, and improves quality of life.