Lower baseline plasma selenium is associated with later suicide attempts in eating disorders: A longitudinal cohort

Individuals with eating disorders are at high risk of suicide attempts (SA), yet nutritional correlates remain underexplored. Selenium, an essential micronutrient with antioxidant and neuroprotective functions, is often deficient in eating disorders. We examined the association between baseline plasma selenium and subsequent SA. We analyzed 658 patients with eating disorders recruited at the University Hospital Center of Montpellier (2012–2014 and 2017–2020). Baseline plasma selenium was quantified by the hospital's biochemistry laboratory. SA occurring after baseline were identified through review of electronic Emergency Department records up to December 1, 2024. Semi-parametric Cox proportional hazards models estimated hazard ratios (HR) for time to first SA. Median plasma selenium was 82.9 μg/L. Over a median 82-month follow-up, 40 participants (6.1%) attempted suicide. Higher selenium levels were associated with lower hazard of SA (HR per 1 SD = 0.59, 95% CI 0.42–0.83, p = 0.002). Results were similar across models adjusted for age, sex, and BMI and, separately, past SA, global eating disorder severity, current depression, psychotropic medication use, and additional C-reactive protein, albumin, zinc, and iron indices. Sensitivity analyses using ≤83 and ≤ 70 μg/L thresholds, restricting to women, and excluding extreme values yielded similar results. Exploratory analyses suggested modest attenuation of associations between purging, tobacco use, alcohol/substance use disorder and SA after adding selenium. Lower baseline selenium was associated with higher subsequent SA hazard. If replicated, selenium status could inform future risk models. • Lower plasma selenium was associated with higher suicide-attempt risk in eating disorders. • Association remained significant in multivariable and era-stratified Cox models. • Selenium partly accounted for effects of purging and substance-use behaviors. • Findings were robust using a clinical deficiency threshold and sensitivity analyses. • Selenium may represent a modifiable biological correlate of suicide risk in eating disorders.