Higher diet quality is associated with a lower prevalence of MASLD and adverse health outcomes: insights from NHANES 2005 to 2020

Abstract Purpose MASLD affects over 30% of the global population increasing the risk of adverse health outcomes. Improvements in diet quality (DQ) may offer a modifiable solution. This study explored the association between DQ and MASLD prevalence, advanced fibrosis, and all-cause mortality. Methods Participants from the NHANES U.S. national database were included in the cross-sectional (n = 20,502) and longitudinal (n = 13,161) analysis. DQ assessed using Healthy Eating Index (HEI)-2020, Mediterranean Diet Score (MedDietScore), and Dietary Approach to Stop Hypertension (DASH). MASLD and advanced fibrosis identified by the Fatty Liver Index and NAFLD fibrosis score, respectively. Mortality was ascertained by the National Death Index. Multivariate logistic regression and Cox proportional hazards analysis estimated odds ratios (OR) for MASLD and hazard ratios (HR) for mortality, with 95% confidence interval. Results Each 1-SD increase (improvement) in HEI-2020 and MedDietScore was associated with 25% lower likelihood of MASLD, while DASH showed 31% lower likelihood. Each 1‑SD increase in HEI‑2020, MedDietScore, and DASH was associated with lower ORs for advanced fibrosis in the MASLD group: 0.83 (0.74–0.94), 0.84 (0.75–0.95), and 0.78 (0.68–0.89), respectively. Over 9.3 years’ median follow‑up, higher DQ was associated with lower all‑cause mortality in the overall population [HEI‑2020: 0.93 (0.86–0.99); MedDietScore: 0.92 (0.86–0.99); DASH: 0.89 (0.83–0.96)], with similar trends in the non‑MASLD group but not in those with MASLD or advanced fibrosis. Conclusions Higher DQ was associated with lower likelihood of MASLD and advanced fibrosis in U.S. adults and was protective against all-cause mortality in overall and non-MASLD population but not in those with MASLD.