Association of dietary flavonoid intake with the prevalence and all-cause mortality of depressive symptoms: Findings from analysis of NHANES

Background: This study aimed to explore the relationship between flavonoids intake and the prevalence and all-cause mortality of depressive symptoms in American adults. Methods: Analyzing 2007-2008, 2009-2010, and 2017-2018 NHANES data, we examined the association between dietary flavonoid and depressive symptoms, including specific subclasses assessment and mortality outcomes tracking until December 31, 2019. Our methodology included weighted multivariate logistic regression, weighted cox proportional hazards regression and restricted cubic spline (RCS) models, supported by stratified and sensitivity analyses. Results: Among the 12,340 participants in total, 1129 exhibited depressive symptoms. The multiple logistic regression analysis showed a significant reduction in total flavonoid and subclass intake in individuals with current depressive symptoms. Adjusted odds ratios (ORs) for the highest quartiles were 0.69 for anthocyanidins and 0.63 for flavones. Interaction effects emerged in non-hypertensive, higher-income, and normal-weight groups for flavones intake. The RCS model indicated an L-shaped association between depressive symptoms and total flavonoid intake, with inflection points at 346 mg/day. During a median follow-up of 119 months, 148 deaths occurred among patients with depressive symptoms. Hazard ratios (HRs) for all-cause mortality showed a significant positive correlation between total flavonoid intake and survival in model 1 (HR = 0.56), with an optimal intake range of 45.2-948.3 mg/day according to the RCS model. Limitations: The study relied on U.S. population survey data, potentially limiting generalizability. Unmeasured confounding factors may exist, and genetic factors were not considered. Conclusions: Adequate intake of flavonoids, especially anthocyanidins and flavones, is associated with reduced odds of depressive symptoms. Additionally, optimal intake ranges of flavonoid intake for mental health benefits were observed for all-cause mortality in population with depressive symptoms.