NCT07424898

Lactose Intolerance and Intestinal Permability

Observational Cross-Sectional Study of Intestinal Permeability in Adults With Lactose Intolerance

• Status: Enrolling By Invitation
• Phase: —
• Study type: Observational
• Enrollment: 200 (estimated)
• Sponsor: Bezmialem Vakif University · Academic / Other
• Sex: All
• Age: 18 Years – 70 Years
• Healthy volunteers: Not accepted

Summary

"This study evaluates the interplay between lactose intolerance, intestinal barrier function (zonulin), and intestinal inflammation (fecal calprotectin) in adults, aiming to clarify their independent contributions to symptom severity and quality of life."

Detailed description

The gastrointestinal system's barrier functions play a critical role in maintaining intestinal and overall health. Tight junction structures, regulated by zonulin, are key components of this barrier, and elevated zonulin levels can increase intestinal permeability, facilitating translocation of luminal particles into the systemic circulation and promoting inflammation. Fecal zonulin-related proteins (ZRP) provide a non-invasive marker of intestinal barrier integrity. Calprotectin, a pro-inflammatory protein complex released from neutrophils, serves as a reliable biomarker of mucosal inflammation. While typically normal in functional disorders such as irritable bowel syndrome (IBS), fecal calprotectin (FC) is significantly elevated in inflammatory bowel diseases (IBD), helping to distinguish organic inflammatory conditions from functional disorders. Lactose intolerance (LI) results from lactase deficiency and is characterized by abdominal pain, bloating, and diarrhea. Traditionally attributed to mechanical and fermentative processes, recent evidence suggests that immunological and inflammatory mechanisms may also contribute. LI can be primary (genetic lactase deficiency) or secondary (due to epithelial damage or barrier dysfunction), with barrier disruption potentially exacerbating symptom severity. Recent studies have reported elevated fecal calprotectin in individuals with self-reported milk intolerance (Seidita et al., 2023), even among those confirmed as lactose intolerant by hydrogen breath testing, suggesting that additional inflammatory or allergic mechanisms may be involved. Moreover, dietary interventions in IBS patients with food intolerances, including lactose, have been shown to significantly reduce calprotectin levels (Schnedl et al., 2023), indicating that inflammation may be modifiable. Therefore, evaluating zonulin and calprotectin levels in lactose-intolerant adults can provide insights not only into mechanical or chemical causes of symptoms but also into intestinal barrier dysfunction and underlying inflammation. Current literature on combined assessment of these biomarkers in adults is limited. This study aims to: Investigate the relationship between lactose intolerance and zonulin/fecal calprotectin levels. Assess the independent contribution of zonulin (intestinal permeability) separate from calprotectin (inflammation). Explore associations between these biomarkers, symptom severity, and quality of life.

Conditions

• Lactose Intolerance, Adult Type
• Intestinal Permability
• IBS (Irritable Bowel Syndrome)

Timeline

• Start date: 2026-02-10
• Primary completion: 2026-12-15
• Completion: 2027-06-15
• First posted: 2026-02-20
• Last updated: 2026-02-25

Locations

1 site across 1 country: Turkey (Türkiye)