Irritable bowel syndrome (IBS) affects roughly 11% of adults worldwide and significantly impacts quality of life, yet the biological mechanisms behind it — particularly altered intestinal permeability (“leaky gut”) — have been hard to measure reliably. Existing tests (like the lactulose-mannitol assay or intestinal biopsies) are invasive, time-consuming, or unreliable. Identifying a simple blood-based biomarker like zonulin could make diagnosis and future targeted treatment more practical and accessible.
The study compared serum zonulin and intestinal fatty acid binding protein (I-FABP) levels across four groups: diarrhea-predominant IBS (IBS-D, n=50), constipation-predominant IBS (IBS-C, n=50), celiac disease (n=53), and healthy controls (n=42). Zonulin levels were significantly higher in both IBS-D and IBS-C compared to healthy controls, and were comparable to levels seen in active celiac disease. I-FABP levels, however, were not elevated in IBS patients, suggesting no significant enterocyte (intestinal cell) damage — differentiating the mechanism of permeability change in IBS from that in celiac disease.
Singh P, Silvester J, Chen X, Xu H, Sawhney V, Rangan V, Iturrino J, Nee J, Duerksen DR, Lembo A. Serum zonulin is elevated in IBS and correlates with stool frequency in IBS-D. United European Gastroenterology Journal. 2019;7(5):709-715. doi:10.1177/2050640619826419
