The Effect of a Low-FODMAP Diet on Quality of Life, Severity of Symptoms and Leaky Gut in Patients with Irritable Bowel Syndrome.

Objective: We aimed to investigate the effects of a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet on symptom severity, quality of life, and fecal zonulin levels in patients with irritable bowel syndrome (IBS). Methods: Twenty-four patients with IBS were prospectively randomized to either a low-FODMAP diet (LFD) or a traditional diet (TD) for 4 weeks. IBS Symptom Severity Scale (IBS-SSS), IBS Quality of Life (IBS-QOL), and fecal zonulin levels were assessed at baseline and week 4 in both groups. In the LFD group, FODMAP-containing foods were gradually reintroduced after week 4, and all assessments were repeated at week 16. Changes in laboratory parameters, fecal zonulin levels, IBS-SSS, and IBS-QOL scores were evaluated. Results: Fecal zonulin levels did not differ significantly between groups at baseline or week 4, and no significant within-group changes were observed over time (all p > 0.05). IBS-SSS scores improved significantly at week 4 in both groups compared with the baseline (p < 0.05), with no significant difference in the magnitude of improvement between groups (p > 0.05). In the LFD group, IBS-SSS scores increased at week 16 compared with week 4 (p < 0.05). Similarly, IBS-QOL scores improved significantly at week 4 in both groups (p < 0.05), without significant between-group differences (p > 0.05). In the LFD group, IBS-QOL scores returned to baseline levels by week 16. Conclusions: Both the LFD and TD were associated with significant short-term improvements in IBS symptom severity and quality of life. However, the LFD did not demonstrate superiority over the TD. Furthermore, no statistically significant changes in fecal zonulin levels were observed in either group, although these findings should be interpreted cautiously. In the LFD group, some improvements observed at week 4 were attenuated following FODMAP reintroduction at week 16; however, these findings represent exploratory within-group observations and should not be interpreted as evidence of long-term treatment efficacy or sustained benefit following FODMAP reintroduction.