Role of BMI in the relationship between dietary inflammatory index and non-alcoholic fatty liver disease: an intermediary analysis

Previous studies have indicated that a pro-inflammatory diet is associated with non-alcoholic fatty liver disease (NAFLD), but the role of BMI remains ambiguous. We aim to study the intermediary effect of BMI on the relationship between dietary inflammatory properties and NAFLD.A total of 19536 adult participants from the National Health and Nutrition Examination Surveys (NHANES) were included. Dietary inflammatory index (DII) was used to evaluate the dietary inflammatory properties and NAFLD was diagnosed by non-invasive biomarkers. Weighted multivariable logistic regression models estimated ORs and 95% CIs between DII and incidence of NAFLD. Interaction effect between DII and BMI on NAFLD was tested and the mediation analysis of BMI was performed.Higher DII scores, representing higher inflammatory potential of diet, were positively associated with a higher risk of NAFLD. Compared with the first quartile of DII, people from the second quartile (OR: 1.23 [95% CI: 1.04, 1.46]) to the fourth quartile (OR: 1.59 [95% CI: 1.31, 1.94]) have a higher risk of NAFLD before adjustment for BMI. The overall association was completely mediated by BMI (89.19%).Our findings suggested that a higher pro-inflammatory potential diet was associated with a higher prevalence of NAFLD, and this association might be mediated by BMI.