A Mediterranean Diet Pattern Improves Intestinal Inflammation Concomitant with Reshaping of the Bacteriome in Ulcerative Colitis: A Randomised Controlled Trial.

Journal of Crohn's & colitis. 2023;17(10):1569-1578

Plain language summary

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) with debilitating symptoms. Patients live with considerable symptom burden, increased risk of disability, and lower quality of life despite medical treatment. The aim of this study was to investigate the efficacy of the Mediterranean Diet Pattern (MDP) compared with a Canadian Habitual Diet Pattern (CHD) on UC disease activity, inflammation, and the gut microbiome. This study was a randomised controlled trial where participants were randomly assigned to follow the MDP or CHD for 12 weeks. Results showed that: - the MDP reduces clinical symptoms and reduces inflammation. - the MDP promotes faecal secretory immunoglobulin A [the principal weapon protecting us from pathogens and toxins that might otherwise penetrate mucosal surfaces. - the MDP is positively associated with microbes that produce potentially beneficial metabolites. - the MDP is negatively associated with microbes predicted to carry pathobiont traits. - the MDP increases faecal short-chain fatty acids production. Authors conclude that the MDP is well tolerated and is a reasonable, healthy eating pattern that practitioners can recommend to patients with UC in remission to prevent relapses, in addition to their standard medical therapy.


BACKGROUND AND AIMS Dietary patterns are important in managing ulcerative colitis [UC], given their influence on gut microbiome-host symbiosis and inflammation. We investigated whether the Mediterranean Diet Pattern [MDP] vs the Canadian Habitual Diet Pattern [CHD] would affect disease activity, inflammation, and the gut microbiome in patients with quiescent UC. METHODS We performed a prospective, randomised, controlled trial in adults [65% female; median age 47 years] with quiescent UC in an outpatient setting from 2017 to 2021. Participants were randomised to an MDP [n = 15] or CHD [n = 13] for 12 weeks. Disease activity [Simple Clinical Colitis Activity Index] and faecal calprotectin [FC] were measured at baseline and week 12. Stool samples were analysed by 16S rRNA gene amplicon sequencing. RESULTS The diet was well tolerated by the MDP group. At week 12, 75% [9/12] of participants in the CHD had an FC >100 μg/g, vs 20% [3/15] of participants in the MDP group. The MDP group had higher levels of total faecal short chain fatty acids [SCFAs] [p = 0.01], acetic acid [p = 0.03], and butyric acid [p = 0.03] compared with the CHD. Furthermore, the MDP induced alterations in microbial species associated with a protective role in colitis [Alistipes finegoldii and Flavonifractor plautii], as well as the production of SCFAs [Ruminococcus bromii]. CONCLUSIONS An MDP induces gut microbiome alterations associated with the maintenance of clinical remission and reduced FC in patients with quiescent UC. The data support that the MDP is a sustainable diet pattern that could be recommended as a maintenance diet and adjunctive therapy for UC patients in clinical remission. ClinicalTrials.gov no: NCT0305371.

Lifestyle medicine

Fundamental Clinical Imbalances : Immune and inflammation
Patient Centred Factors : Mediators/Ulcerative colitis
Environmental Inputs : Diet ; Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood ; Stool

Methodological quality

Jadad score : 3
Allocation concealment : Yes