Relationship between Markers of Gut Barrier Function and Erythrocyte Membrane PUFAs in Diarrhea-Predominant IBS Patients Undergoing a Low-FODMAP Diet

Many patients with irritable bowel syndrome (IBS) have a compromised intestinal barrier associated with low-grade inflammation. Polyunsaturated fatty acids (PUFAs) are potential mediators of inflammation: omega-6 PUFAs are pro-inflammatory, while omega-3 PUFAs are antioxidant and anti-inflammatory. Zonulin is a potential biomarker for small intestinal permeability (s-IP). This study investigated the relationship between PUFAs and gastrointestinal (GI) barrier integrity in IBS patients with predominant diarrhea (IBS-D). We evaluated GI barrier function indicators in the urine and bloodstream and erythrocyte membrane PUFA composition in 38 IBS-D patients (5 men, 33 women, 44.11 +/- 1.64 years), categorized at baseline by fecal zonulin levels into high (>= 107 ng/mL, H-FZ) and normal (<107 ng/mL N-FZ) groups. Evaluations were conducted prior to and following a 12-week diet low in FODMAPs (LFD). At baseline, H-FZ patients had s-IP significantly higher than the reference value, lower n-3 PUFAs levels, and higher n-6/n-3 PUFAs and arachidonic acid (AA) to eicosapentaenoic acid (EPA) ratios than N-FZ. After LFD, H-FZ patients showed significant increases in n-3 PUFAs levels; decreases in n-6 PUFAs, n-6/n-3 PUFAs and AA/EPA ratios; and improved s-IP. The n-6/n-3 PUFAs ratio positively correlated with fecal zonulin levels in all subjects. These findings highlight the relationship between PUFAs and the intestinal barrier, suggesting their role in IBS-D pathophysiology and confirming the positive effects of LFD in managing IBS-D.