Vitamin D Supplementation for Adult Long‐Term Psychiatric Inpatients

Low vitamin D status is associated with various adverse physical health outcomes including osteoporosis and compromised immune functioning. Emerging research has shown that supplementation can yield selective benefit on symptomatology in serious mental illness. Despite its known benefits, vitamin D screening is not standard in psychiatric care. This cross‐sectional observational study assessed serum 25‐hydroxyvitamin D (25[OH]D) levels among psychiatric inpatient service users on two long‐stay wards. It was hypothesized that 25(OH)D levels would significantly differ between those taking cholecalciferol and those not, with further differences by age (< 64 vs. ≥ 65) and sex. Randomly selected participants ( N = 53) on a hospital diet completed serum 25(OH)D screening. One‐way ANOVA assessed differences in vitamin D categories, and three‐way ANOVA tested main effects and interactions of supplementation status (cholecalciferol n = 23 vs. non‐supplemented n = 30), age, and sex. Psychiatric inpatients without cholecalciferol supplementation have a higher prevalence of suboptimal vitamin D levels ( p < 0.001). Most participants had a diagnosis of schizophrenia or schizoaffective disorder. Vitamin D status ranged across the full spectrum. Among non‐supplemented patients, 80% had suboptimum 25(OH)D levels (< 75 nmol/L). In contrast, 83% of those taking cholecalciferol had optimum levels. A significant interaction was found between supplementation, age, and sex, with the most notable benefits for males and females aged 18–64, and males 65 +. This study contributes evidence that routine screening and vitamin D supplementation may offer benefit for long‐term psychiatric inpatients. The results are consistent with studies containing a larger and diverse inpatient sample size, in multiple regions globally.