Effect of gluten and FODMAP elimination in celiac patients on gut inflammatory biomarkers

Background: Reduced dietary intake of fermentable oligo-, di- and monosaccharides and polyols (FODMAPs) has been suggested as a strategy to improve gastrointestinal (GI) symptoms in people diagnosed with irritable bowel syndrome (IBS). In a Norwegian study of patients with celiac disease (CD), experiencing persistent GI symptoms similar to those observed in IBS-patients, reducing FODMAPs gave symptom relief. Based on the same study, the aim of the current master thesis was to investigate the effects of FODMAP restriction on fecal neutrophil gelatinaseassociated lipocalin (NGAL); a potential biomarker of gut integrity and inflammation, and effects on the concentration of fecal short-chain fatty acids (SCFAs); metabolites of microbial fermentation. Also, the associations between GI symptoms and fecal NGAL and SCFA were investigated. Furthermore, the potential for using a Luminex-based method for measuring fecal NGAL, as an alternative to ELISA, was investigated. Methods: The study, which followed a randomized parallel design, included adult CD patients on a gluten-free diet (GFD) having persistent GI symptoms. The participants were randomized to consume a low-FODMAP diet (LFD) in addition to their GFD (LFD-group, n=34) or to continue their regular GFD (controls, n=36) and were followed up for four weeks as out-patients at the clinic of Oslo University. Sampling of feces was performed at baseline and at 4-week follow-up. NGAL was measured in fecal extracts using ELISA, while fecal SCFAs were analysed using GCFID technology. Also, a Luminex-based method was established, and compared to that of ELISA. Results: Reducing the intake of FODMAPs did not affect fecal NGAL levels when comparing 4-week values between the LFD group and the controls using a linear regression model, controlling for baseline values. Similar linear regression models analysing the SCFAs indicated a significant effect of the intervention (p<0.05) for propionic acid and valeric acid, but the effects on both SFCAs were dependent on the baseline ...