TOPLINE:

Among patients with inflammatory bowel disease (IBD), microbial diversity was lowest in those with Crohn’s disease, where coffee and whole wheat bread intake was linked to reduced disease activity status via mediation by specific bacteria and metabolites. In those with ulcerative colitis, fruit and coffee intake was linked to lower C-reactive protein (CRP) and calprotectin levels by enhancing microbial richness.

METHODOLOGY:

• Researchers conducted a prospective longitudinal study to examine how gut microbiota link dietary patterns to clinical characteristics in patients with IBD compared with healthy control individuals.
• Participants completed a validated food frequency questionnaire online covering 58 food items, with intake frequency ranging from never to two or more times a week.
• Clinical activity status was evaluated with the Harvey-Bradshaw Index for Crohn’s disease and Colitis Activity Index for ulcerative colitis, and nutritional quality was assessed using several indexes (eg, the Healthy Eating Index 2015).
• Blood and stool samples were collected to measure biomarkers, including calprotectin and CRP; stool samples obtained at baseline and 6 months were used for microbiome analyses.
• Genomic DNA was extracted from stool samples for taxonomic and functional profiling of the gut microbiome, and causal mediation analyses were performed to identify microbial features mediating associations between diet and health outcomes.

TAKEAWAY:

• Researchers included 100 healthy adult control individuals, 49 adult patients with Crohn’s disease, and 49 with ulcerative colitis.
• Patients with IBD had lower dietary diversity and nutritional adequacy than healthy control individuals. Patients with Crohn’s disease consumed more soft drinks and processed foods, and both IBD groups had lower intakes of fiber, fat, alcohol, and sugar.
• Microbiome diversity was lowest in patients with Crohn’s disease, who also showed greater dysbiosis than patients with ulcerative colitis and healthy control individuals. Higher dietary quality was associated with increased microbial diversity and decreased dysbiosis.
• In Crohn’s disease, coffee and whole wheat bread intake was associated with lower Harvey-Bradshaw Index scores through mediation by specific bacterial species and metabolites. In ulcerative colitis, coffee and fruit intake was linked to lower CRP and calprotectin levels through enhanced microbial richness, whereas chocolate consumption was linked to increased CRP levels mediated by changes in specific bacterial taxa.

IN PRACTICE:

“These findings highlight a coherent mechanistic route whereby diet influences inflammation through modulation of microbial [short-chain fatty acid] production and related metabolic functions,” the authors wrote. “From a translational perspective, our results provide mechanistic support for dietary interventions as adjuncts to medical therapy in IBD.”

SOURCE:

The study was led by Luis Mayorga, Microbiome Lab, Vall d’Hebron Institut de Recerca, Barcelona, Spain. It was published online in Gut.

LIMITATIONS:

Reliance on self-reported dietary questionnaires may resulted in misclassification of dietary intake. Further analysis is needed to confirm these mediations in controlled dietary intervention trials and independent IBD cohorts.

DISCLOSURES:

This study was supported by grants from the Instituto de Salud Carlos III and co-funded by the European Union, the Ministry of Economy and Competitiveness, FEDER (EU), and the AGAUR. The authors reported having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.