Association between iron intake and risk of all-cause mortality in patients with nonalcoholic fatty liver disease: a retrospective study of NHANES

Background: The objective of this study was to assess how dietary iron intake relates to the risk of all-cause mortality among individuals with non-alcoholic fatty liver disease (NAFLD). Methods: The research comprised a total of 9240 individuals diagnosed with NAFLD, obtained from the National Health and Nutrition Examination Survey conducted between 2007 and 2018. To investigate the relationship between the intake of dietary iron and all-cause mortality, we utilized Cox proportional hazard models and restricted cubic splines (RCS). Results: During the median follow-up period of 9.4 years, a total of 828 participants (6.82% of the total cohort) died. After adjusting for all confounding factors, individuals in the second quartile (Q2) exhibited the lowest mortality risk (risk ratio: 0.73 [0.55, 0.98]) compared to those in the first quartile. The risk curve illustrates a U-shaped relationship between mortality rate and dietary iron intake. Furthermore, we identified different breakpoints for iron intake across various demographic groups: 15.740 mg/d for young and middle-aged men, 12.565 mg/d for young and middle-aged women, 14.8225 mg/d for elderly men, and 12.1850 mg/d for elderly women. Conclusion: Our study uncovers a U-shaped relationship between iron intake and all-cause mortality in adult patients with NAFLD in the United States. Both excessive and insufficient iron intake are linked to an elevated risk of death.