4.3.4. Analysis of Intestinal Permeability Markers
The measurement of I-FABP levels was performed in Örebro, Sweden, using an enzyme-linked immunosorbent assay (I-FABP, Human, ELISA kit, HK406, Hycult Biotech, Uden, The Netherlands), following the manufacturer’s instructions. Furthermore, the fecal samples used for zonulin measurement were diluted to the recommended working concentration in stool sample tubes (K6998SAS; Immundiagnostik AG, Bensheim, Germany) using sample buffer. Zonulin was measured using a commercial enzyme-linked immunosorbent assay kit (K5600, Immundiagnostik AG, Bensheim, Germany) following the manufacturer’s instructions, as described before [