PP404 - IMPACT OF THE NOVEL UC-TREAT DIET ON THE GUT MICROBIOME AND ITS TOLERABILITY IN HEALTHY ADULTS AND ADULTS WITH QUIESCENT ULCERATIVE COLITIS

PP404

IMPACT OF THE NOVEL UC-TREAT DIET ON THE GUT MICROBIOME AND ITS TOLERABILITY IN HEALTHY ADULTS AND ADULTS WITH QUIESCENT ULCERATIVE COLITIS

S. Mckirdy¹, D. Gaya², R. K. Russell³, R. Hansen⁴, J. MacDonald⁵, J. P. Seenan⁵, B. Nichols¹, A. Koutsos¹, K. Gerasimidis^1,*

¹Human Nutrition, University of Glasgow, ²Gastroenterology, Glasgow Royal Infirmary, Glasgow, ³Paediatric Gastroenterology, Royal Hospital for Children & Young People, Edinburgh, ⁴Division of Clinical and Molecular Medicine, University of Dundee, Dundee, ⁵Gastroenterology, Queen Elizabeth University Hospital, Glasgow, United Kingdom

Rationale: Microbiome modifying treatments may improve outcomes in Ulcerative Colitis (UC). We tested the gastrointestinal tolerability and microbiome-modifying effects of a novel, “eubiotic” diet (UC-TREAT) in individuals with quiescent UC and healthy controls (HC).

Methods: 36 adults (18 HC and 18 with quiescent UC) underwent a 10-day “run-in” phase, a 5-day “ramping” phase, and a 10-day “full” dietary intervention with UC-TREAT. UC-TREAT is rich in fermentable carbohydrates (providing >35g/day fibre), fermented foods, berries, and a micronutrient supplement. Faecal and blood samples were collected to assess microbiome (16S rRNA), bacterial load (qPCR), SCFA (GC-FID), faecal calprotectin (FCAL), and inflammatory cytokines (MSD U-PLEX). GI tolerance (GSRS-IBS) and disease activity (DA, SCCAI) were also assessed.

Results: Fibre intake doubled during UC-TREAT (9.8 vs 20.8 g/1000kcal/d) and fermented food intake increased by 4.3 portions/d. In UC and HC, faecal acetate [median(IQR) µmol/g: +11.1(25.23); +15.2(37.2)], total SCFA [+11.6(19.72); +23.1(53.92)], and bacterial load [log10 16S rRNA gene copies/g: +0.07 (0.22); +0.06(0.18)] increased, respectively (all p<0.05). Butyrate increased in UC [+2.79(5.63) µmol/g]. In UC, bloating transiently increased [+2(4.3)], while HC reported prolonged bloating [+2.5(4)]. In UC, all participants remained in clinical remission, FCAL remained unchanged, and plasma IL-1β decreased [-0.034(0.043) pmol/mL]. Microbiome composition changed in UC (R²=1.5%, p<0.01), but not in HC. Abundance of butyrate producers, including Anaerostipes hadrus, Bacteroides vulgatus, and Faecalibacterium prausnitzii, increased (FDR<0.2).

Conclusion: UC-TREAT increased faecal SCFA, bacterial load, and SCFA-producing taxa, without negatively affecting FCAL or GI tolerance in quiescent UC. These proof-of-concept results warrant further investigation in a larger RCT.

Disclosure of Interest: S. Mckirdy: None declared, D. Gaya: None declared, R. Russell Consultant for: Nestle, AbbVie, Celltrion, Janssen, Lilly & Pfizer, Speakers Bureau of: Nestle, AbbVie, Celltrion, Janssen, Lilly & Pfizer, R. Hansen: None declared, J. MacDonald: None declared, J. P. Seenan Consultant for: AbbVie, Bristol Myers Squibb, Dr Falk Pharma, and Galapagos, Speakers Bureau of: AbbVie, Fresenius Kabi, Galapagos, Janssen-Cilag, Pharmacosmos, Takeda, and Tillotts Pharma, B. Nichols: None declared, A. Koutsos: None declared, K. Gerasimidis Grant / Research Support from: Nestle Health Science, Speakers Bureau of: Nutricia, Dr Falk Pharma, Abbott, Servier, Mylan, and Baxter