P692 Exploring relationships between microbiome, faecal calprotectin and healthy eating index in patients with ulcerative colitis: Interim analyses of a randomised controlled trial

Abstract

Abstract Background This study explored relationships between gut microbiome, faecal calprotectin (FCP) and an adapted Canadian healthy eating index (CHEI) in ulcerative colitis (UC) patients enrolled in a randomised controlled dietary intervention trial. Methods Patients with both active and quiescent disease were recruited from the Foothills Medical Center in Calgary, Alberta, Canada and randomised to either an 8-week reduced sulfur anti-inflammatory diet intervention (INT; n = 14) or conventional management control group (CM; n = 10). Each INT patient met with a registered dietitian for diet teaching, in person at baseline, over the phone at 2 weeks, and in person at 4 weeks. Stool samples and 24-h dietary recalls were collected at baseline and 8 weeks. DNA from stool samples was extracted and the V4 region of the 16S gene was sequenced. FCP was extracted and analyzed using the EK-CAL ELISA. An adapted CHEI was generated from diet recalls using previously validated scoring guidelines. Relationships between variables were analyzed using analysis of variance and chi-squared. Results Mean age of the sample was 36.3 (SD=8.7) and 58% were male. Baseline medications included aminosalicylates (71%), steroids (50%), biologics (33%), immunosuppressants (25%) and 21% of patients had taken antibiotics within the last 3 months. Α-diversity, or within-community diversity, significantly increased in the CM group and remained stable in the INT group over time (p = 0.005). Β-diversity, or between-community diversity appeared to increase in the intervention group over time (p < 0.01); however, this may have been influenced by antibiotic use in five patients. Significant differential features between the CM and INT groups (p < 0.01) at the genus level were identified in the phyla Firmicutes and Proteobacteria, specifically Catenibacterium, Parvimonas, Coprococcus_2 and Desulfovibrio. FCP appeared to be different between the groups (p = 0.05) with a greater percentage of INT patients moving from high FCP (>250 mg/g) to low FCP (<250 mg/g); 50% of INT patients and 20% of CM patients normalised FCP levels. As CHEI increased in the whole sample, indicating higher diet quality, FCP decreased significantly (p = 0.04). Conclusion In an interim analysis, a dietary intervention shows efficacy in manipulating the microbiome. Higher diet scores representing a healthier diet were also related to lower faecal calprotectin levels.