Colon to Rectum
Clin Gastroenterol Hepatol. 2022;20(12):2876–87.e15
Efficacy and acceptability of dietary therapies in non-constipated irritable bowel syndrome: A randomized trial of traditional dietary advice, the low FODMAP diet, and the gluten-free diet
Background and aims: Various diets are proposed as first-line therapies for non-constipated irritable bowel syndrome (IBS) despite insufficient or low-quality evidence. A randomized trial comparing traditional dietary advice (TDA) against the low fermentable oligo-, di-, monosaccharides and polyols (FODMAP) diet (LFD) and gluten-free diet (GFD) was performed.
Methods: Patients with Rome IV-defined non-constipated IBS were randomized to TDA, LFD, or GFD (the latter allowing for minute gluten cross-contamination). The primary end point was clinical response after 4 weeks of dietary intervention, as defined by ≥ 50-point reduction in IBS symptom severity score (IBS-SSS). Secondary end points included (1) changes in individual IBS-SSS items within clinical responders, (2) acceptability and food-related quality of life with dietary therapy, (3) changes in nutritional intake, (4) alterations in stool dysbiosis index, and (5) baseline factors associated with clinical response.
Results: The primary end point of ≥ 50-point reduction in IBS-SSS was met by 42% undertaking TDA (14/33), 55% for LFD (18/33), and 58% for GFD (19/33) (p = 0.43). Responders had similar improvements in IBS-SSS items regardless of their allocated diet. Individuals found TDA cheaper (p < 0.01), less time-consuming to shop (p < 0.01), and easier to follow when eating out (p = 0.03) than the GFD and LFD. TDA was also easier to incorporate into daily life than the LFD (p = 0.02). Overall reductions in micronutrient and macronutrient intake did not significantly differ across the diets. However, the LFD group had the greatest reduction in total FODMAP content (27.7 g/day before intervention to 7.6 g/day at week 4) compared with the GFD (27.4 g/day to 22.4 g/day) and TDA (24.9 g/day to 15.2 g/day) (p < 0.01). Alterations in stool dysbiosis index were similar across the diets, with 22–29% showing reduced dysbiosis, 35–39% no change, and 35–40% increased dysbiosis (p = 0.99). Baseline clinical characteristics and stool dysbiosis index did not predict response to dietary therapy.
Conclusions: Traditional dietary advice (TDA), low FODMAP diet (LFD), and gluten-free diet (GFD) are effective approaches in non-constipated irritable bowel syndrome (IBS), but TDA is the most patient-friendly in terms of cost and convenience. TDA was recommend as the first-choice dietary therapy in non-constipated IBS, with LFD and GFD reserved according to specific patient preferences and specialist dietetic input.