Biomarkers in body fluids and their detection techniques for human intestinal permeability assessment

Intestinal permeability (IP) is a crucial index for intestinal tract integrity, reflecting intestinal barrier function, injury, diseases, and related systemic conditions. However, current mainstream testing methods are invasive and qualitative. Biomarkers for IP in body fluids offer noninvasive and quantitative advantages for IP assessment while pose challenges for high-performance detection techniques.

This review introduces the main types of biomarkers for IP, including sugar probes, endotoxin, D-lactic acid, intestinal fatty acid-binding protein, diamine oxidase, citrulline, zonulin and lipopolysaccharide-binding protein. Their sources, associated diseases and detection techniques are summarized, and the regulation of intestinal ecosystem and IP by diet are also briefly discussed.

By investigating existing studies, various biomarkers in body fluids and their detection techniques are introduced, and the effectiveness and realizability of IP assessment with body fluid markers are demonstrated. This review can be as a reference for gastroenterologists, laboratory technicists and researchers.

Body fluid biomarker detection provides a promising proach for IP in vitro assessment. To improve the feasibility in clinics, more types of biomarkers, more accurate physiological and pathological mechanisms, and more innovative sensing technologies are expected to be explored and developed. It is foreseeable that fast, precise, and on-site IP assessment will contribute to the clinical diagnosis and monitoring of intestinal and secondary diseases.