Inverse Association Between Dietary Niacin Intake and Prevalence of Depressive Symptoms in Adults With Metabolic-Associated Fatty Liver Disease: A Cross-Sectional Study.

Depression and fatty liver disease exhibit a close bidirectional relationship, and depressed patients with fatty liver disease represent a clinically important subgroup. Although niacin intake has been shown to ameliorate fatty liver disease, its effects on depression remain inconsistent. This cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) 2017-2020 to investigate the association between niacin intake and depression in individuals with metabolic dysfunction-associated fatty liver disease (MAFLD). Multivariate logistic regression was applied to evaluate the linear association, while smooth curve fitting and threshold effect analysis were performed to characterize nonlinear relationships. Subgroup analyses and interaction tests were conducted to assess the robustness of the findings. A nonlinear association was observed between niacin intake and depression in MAFLD patients. Threshold analysis identified an inflection point at approximately 10.24 mg/day, below which a significant inverse association was found (OR 0.80; 95% CI: 0.68-0.93), whereas no significant relationship was detected above this threshold. Subgroup analyses and interaction tests consistently confirmed the robustness of these findings. In conclusion, moderate niacin intake is associated with a lower risk of depression in patients with MAFLD, and the identified threshold of approximately 10.24 mg/day may serve as a reference value for future research.