Vitamin D and Suicidal Ideation: A Predictive Model Based on NHANES Database

Objective This study sought to determine the demographic, socioeconomic, and biochemical prognostic factors for suicidal ideation in a nationally representative cohort of healthy adults in the United States and to construct a clinically feasible predictive model. Methods We analyzed data from the National Health and Nutrition Examination Survey (NHANES), restricting the sample to individuals free of severe physical or psychiatric conditions. Suicidal ideation served as the primary outcome measure, with prognostic variables including sex, age, race, military service background, educational attainment, marital status, household size, income-to-poverty ratio, and vitamin D biomarkers (VD2 and VD3). Multivariate logistic regression was used to identify significant prognostic factors using a nomogram developed for risk visualization. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC) with internal validation conducted via bootstrap resampling. Results Multivariable analysis revealed that younger age (odds ratio [OR] 0.99, p = 0.003), never having been married (OR 2.07, p < 0.001), and being widowed, divorced, or separated (OR 1.81, p < 0.001) correlated with increased odds of suicidal ideation. Additionally, a lower income-to-poverty ratio (OR 0.83, p < 0.001) and decreased VD3 concentration (OR 0.99, p < 0.001) emerged as predictive factors. The model showed moderate discriminative ability with an AUC of 0.721 (95% CI: 0.690–0.751), and internal validation via bootstrap resampling yielded a corrected C-index of 0.714. Conclusion Key demographic, socioeconomic, and nutritional factors, specifically marital status, economic hardship, and vitamin D status, represent significant prognostic indicators for suicidal ideation in the general U.S. adult population. The resulting nomogram offers a practical instrument for personalized risk evaluation and underscores potential targets for public health prevention initiatives.