Dietary inflammatory index scores did not correlate with endoscopic or biomarker measures of IBD activity.
Background & Rationale
Inflammatory bowel disease (IBD), encompassing Crohn’s disease and ulcerative colitis, is characterised by chronic inflammation of the gastrointestinal tract. While genetic predisposition and immune dysregulation are central to IBD pathogenesis, environmental factors, particularly diet, are increasingly recognised as potential modulators of disease course. The Dietary Inflammatory Index (DII) is a scoring system designed to reflect the inflammatory potential of an individual’s diet, based on the combined effects of various foods and their nutrient profiles. Previous investigations exploring the association between diet and IBD have yielded inconsistent results; this study aimed to investigate the relationship between DII scores and objective measures of disease activity in patients with established IBD.
Study Design
This was a cross-sectional observational study conducted at a single academic medical centre. Consecutive adult patients with confirmed Crohn’s disease or ulcerative colitis undergoing routine colonoscopy with ileoscopy were recruited. Dietary intake was assessed using a validated food frequency questionnaire (FFQ). The DII was calculated from the FFQ data, with higher scores indicating a more pro-inflammatory dietary pattern. Objective disease activity was assessed by endoscopic scores using the Simple Endoscopic Score for Crohn’s Disease (SES-CD) and the Mayo Endoscopic Subscore (MES), alongside serum biomarkers including C-reactive protein (CRP) and faecal calprotectin. Spearman’s rank correlation coefficients were used to assess associations between DII scores and disease activity parameters.
Patient Population
A total of 128 patients with IBD were enrolled: 69 with Crohn’s disease and 59 with ulcerative colitis. The mean age of the cohort was 45.6 years, with 57.8% identified as female. The median disease duration was 8 years. 62.5% of patients were receiving biological therapy, 25.8% were taking immunomodulators, and 11.7% were on corticosteroids at the time of assessment. The mean Body Mass Index (BMI) was 26.3 kg/m².
Key Findings
The study found no statistically significant correlations between DII scores and any measure of objective disease activity. The Spearman’s rank correlation coefficient between DII and SES-CD was 0.07. Similarly, no correlation was observed between DII and MES (correlation coefficient of -0.02). No significant associations were found between DII scores and levels of CRP (correlation coefficient of 0.03) or faecal calprotectin (correlation coefficient of 0.08).
Subgroup analysis stratified by disease phenotype (Crohn’s disease vs. ulcerative colitis) and medication status (biological therapy vs. no biological therapy) also failed to reveal any significant correlations. The mean DII score for the entire cohort was 1.84. Patients with Crohn’s disease had a mean DII score of 1.78, while those with ulcerative colitis had a mean DII score of 1.91.
Discussion
The absence of a correlation between DII scores and objective disease activity measures suggests that overall dietary inflammatory potential, as assessed by the DII, does not readily predict the level of active inflammation in IBD patients within this cohort. This contrasts with some prior research which identified links between specific dietary components and IBD symptomology. The study’s cross-sectional design limits ability to infer causality; it is possible that disease activity influences dietary choices, rather than vice versa.
The high proportion of patients receiving biological therapies may have masked potential associations, as these agents powerfully control inflammation and could diminish the dietary signal. The study reports that all patients tolerated the FFQ well and there were no reported adverse events related to the assessment. Tolerability of current IBD medications was reported as generally good, with no unexpected patterns relating to DII scores.
Authors’ Conclusions
The authors concluded that the DII, when used as a global measure of dietary inflammatory potential, is not associated with objective disease activity in patients with Crohn’s disease or ulcerative colitis. They suggest further investigation with more refined dietary assessments and longitudinal study designs is warranted to explore specific dietary components and their impact on IBD outcomes.
Reference
de Oliveira RMV, Vasques ACJ, Romero SA, Shivappa N, Wirth MD, Hébert JR, Reis GFSR, Nagasako CK. Dietary inflammatory index and objective disease activity in IBD: no association found. European journal of clinical nutrition. 2026; 70: 870-877. DOI: 10.1038/s41430-026-01713-6.