Short-Term Effects of a Low-FODMAP Diet, Adapted NICE Dietary Advice, and Adapted NICE Dietary Advice Combined with Intermittent Fasting on Symptoms and Quality of Life in Irritable Bowel Syndrome: A Three-Arm, Non-Randomized Controlled Dietary Intervention Study

Background/Objectives: Dietary interventions are central to irritable bowel syndrome (IBS) management, but evidence directly comparing a low-FODMAP diet (LF), adapted NICE dietary advice (NICE), and adapted NICE dietary advice combined with intermittent fasting (NICE–IF) is limited. This study compared the short-term effects of LF, NICE, and NICE–IF on IBS symptom severity and disease-specific quality of life.

Methods

In this prospective, three-arm, non-randomized controlled dietary intervention study, adults with IBS followed LF, NICE, or NICE–IF for two weeks. IBS symptom severity, disease-specific quality of life, and psychological status were assessed using the Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS), the IBS Quality of Life questionnaire (IBS-QOL), and the Hospital Anxiety and Depression Scale (HADS), respectively, at baseline and after the two-week intervention; stool consistency was monitored using the Bristol Stool Form Scale (BSFS). Between-group differences were additionally examined using analysis of covariance (ANCOVA) adjusted for baseline values.