Association between plant-based dietary index and disease severity in patients with ulcerative colitis: a cross-sectional study

Background: Plant foods are naturally rich in anti-inflammatory nutrients. In this cross-sectional study, we assessed the association between the plant-based dietary index (PDI) and Mayo score in patients with ulcerative colitis (UC).

Methods: This analytical cross-sectional study included 158 patients with UC. The Mayo score was used to determine disease severity. An expert nutritionist performed the anthropometric assessments. A 168-item quantitative food frequency questionnaire (FFQ) was used to calculate the PDI, healthy PDI (hPDI), and unhealthy PDI (uPDI). To assess the association between the total Mayo score (as a dependent factor) and different indices of PDI (as an independent variable), the linear regression model was used.

Results: The mean age of participants was 42.52 ± 12.61 years. There were significant differences in the total Mayo score between tertiles of PDI score (p = 0.02). The result of linear regression showed that in the unadjusted model, compared with the patients in the first tertile of PDI, the patients in the second (-0.21 (-1.89, -0.17)), and third tertile (-0.21 (-1.95, -0.16)) had significantly lower total mayo scores. The inverse association remained significant after adjusting for covariates. However, uPDI and hPDI tertiles were not significantly associated with total Mayo scores in the adjusted and unadjusted models.

Conclusion: higher PDI was significantly associated with higher UC severity. However, considering the limitations of the study, more cohort studies are needed to confirm these results.