Background: Previous studies have examined the relationship between vitamin C and depression, but the findings have been inconclusive. The aim of this cross‐sectional study was to investigate the association between serum vitamin C and depression in adults. Methods: Data from the 2017‐2018 National Health and Nutrition Examination Survey (NHANES) cycle were utilized. Weighted multivariable logistic regressions were applied to assess the association between serum vitamin C and depression. Weighted restricted cubic spline (RCS) regression was conducted to explore the dose–response relationship between serum vitamin C and depression. In addition, we performed stratified and sensitivity analyses to evaluate the stability of the results. Results: A total of 4517 participants were included in this study. Among of them, 410 (9.08%) participants suffered depression. In fully adjusted models, serum vitamin C, as a continuous variable, was negatively associated with depression (OR = 0.69, 95% CI: 0.54–0.88, p = 0.003). Similar results were observed when serum vitamin C was analyzed as a categorical variable. The ORs (95% CI) for Q2, Q3, and Q4, with Q1 as the reference, were 1.00 (0.76–1.33), 0.73 (0.54–0.99), and 0.59 (0.42–0.81), respectively. The RCS analysis found a linear negative relationship between serum vitamin C and depression ( p for nonlinearity = 0.579). Additionally, the inverse associations between serum vitamin C and depression remained robust in stratified and sensitivity analyses. Conclusion: Our findings suggested that there was a linear negative relationship between serum vitamin C and depression, indicating that maintaining sufficient serum vitamin C is recommended due to its potential benefits for protecting against depression.
Zhao et al. (Wed,) studied this question.