Abstract: Objective To investigate the association between the Dietary Inflammatory Index (DII) and the detection rate of colorectal polyps. Methods A total of 570 individuals undergoing colonoscopy were enrolled and allocated into a polyp group and a control group. Statistical analyses were performed using t-tests, χ² tests, logistic regression, and restricted cubic spline analysis. Results The polyp group exhibited significantly higher values than the control group (P <0.05) in terms of age, proportion of males, proportion of individuals with a BMI >24 kg/m², proportion with a history of smoking, proportion with no history of NSAID use, and DII score. Multivariable logistic regression analysis revealed that for each unit increase in the DII, the odds ratio (OR) for polyp detection was 1.644 (95% CI: 1.433-1.886). When participants were categorized by DII quartiles (Q1-Q4), the OR for the highest quartile (Q4) versus the lowest quartile (Q1) was 7.470 (95% CI: 4.501-12.399). Subgroup analyses demonstrated that the OR (Q4 vs Q1) was 9.706 in males and 6.961 in females; 6.765 in the BMI ≤ 24 kg/m² group and 8.693 in the BMI >24 kg/m² group; 6.222 for smoking histories of 0 to <10 pack-years, 8.653 for 10 to <30 pack-years, and 20.648 for ≥30 pack-years; and 7.962 for those with a history of NSAID use versus 9.750 for those without. Restricted cubic spline analysis indicated a positive linear dose-response relationship (P<0.01). Conclusion The DII is positively associated with the detection rate of colorectal polyps. This association is stronger in populations who are male, have a BMI >24 kg/m², have a longer history of pack-years of smoking, or have no history of NSAID use.

Key words: Dietary inflammatory index, Colorectal polyps, Gender, Body mass index, Smoking history