Higher Dietary Quercetin Intake Is Associated with Lower Risk of Adverse Outcomes among Individuals with Inflammatory Bowel Disease in a Prospective Cohort Study.

Background: Cumulative preclinical evidence reported quercetin, a major flavonoid, can attenuate the disease activity of inflammatory bowel diseases (IBD). However, there is limited evidence that supports the benefits of quercetin for patients with IBD.

Objectives: To investigate whether dietary quercetin intake is associated with adverse outcomes among individuals with IBD in a prospective cohort study.

Methods: We included 2293 participants with IBD (764 Crohn's disease [CD] and 1529 ulcerative colitis [UC]) from the UK Biobank. Dietary information was collected using validated 24-h dietary assessments, and quercetin intake was estimated based on national nutrient databases. Two outcomes, enterotomy and all-cause mortality, were obtained based on the national data. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs).

Results: After a mean (standard deviation) follow-up of 9.6 (1.8) y, we documented 193 enterotomy events and 176 deaths. Compared with participants with the lowest quartile intake of quercetin, those in the highest quartiles were associated with lower risk of enterotomy (HR: 0.46; 95% CI: 0.28, 0.76) and all-cause mortality (HR: 0.53; 95% CI: 0.33, 0.83) in IBD. The inverse associations between quercetin and enterotomy were consistent in CD (HR: 0.30; 95% CI: 0.12, 0.78) but not UC (HR: 0.58; 95% CI: 0.32, 1.07), while the inverse associations between quercetin and mortality were consistent both in CD (HR: 0.37; 95% CI: 0.15, 0.92) and UC (HR: 0.55; 95% CI: 0.31, 0.95).

Conclusions: Higher dietary intake of quercetin was associated with lower risk of enterotomy and all-cause mortality in IBD. Our study provides novel evidence that further suggests the benefits of quercetin for patients with IBD, while also calling for further validation in other cohorts and clinical trials.