Higher Food Inflammation Index Is Linearly Associated With Higher Risk of <scp>MASLD</scp> : A Cross‐Sectional Study Based on the <scp>NHANES</scp> (1999–2020)

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major global chronic liver condition, with diet-induced inflammation playing a key role in its pathogenesis. This study used 1999-2020 National Health and Nutrition Examination Survey (NHANES) data to assess the association between the Food Inflammation Index (FII) and MASLD risk compared with the Dietary Inflammatory Index (DII). The FII, which is based on 39 food components (via two 24-h dietary recalls), is simpler than the DII (45 components). MASLD was defined as a Fatty Liver Index (FLI ≥ 60) with at least one cardiometabolic risk factor. This study included 25,067 participants (mean age: 49.56 years; 51.51% Male), of whom 6708 met the MASLD diagnostic criteria. Multivariable logistic regression revealed that a 1-standard deviation (SD) increase in the FII was associated with a 7.9% higher MASLD risk (OR = 1.079, 95% CI: 1.025-1.137; <i>p</i> = 0.004) in the fully adjusted model. Compared with the lowest quartile (Q1), the highest FII quartile showed a 30.8% increased risk (OR = 1.308, 95% CI: 1.143-1.496; <i>p</i> < 0.001). Restricted cubic splines confirmed a linear dose-response relationship (<i>p</i>-overall < 0.001; P-nonlinearity = 0.545). Subgroup analyses confirmed consistent FII-MASLD associations across diverse populations (<i>p</i>-interaction > 0.05), with five sensitivity analyses verifying robustness. The area under the curve (AUC = 0.867) of the FII was comparable to that of the DII (AUC = 0.866), but the FII improved risk reclassification by 5.56% (Net Reclassification Improvement [NRI] = 0.0556; <i>p</i> = 0.002) and discrimination by 0.05% (integrated discrimination improvement [IDI] = 0.0005; <i>p</i> = 0.015). The FII effectively assesses dietary inflammation in patients with MASLD, supporting targeted nutritional interventions, but further validation is needed.