Materials and Methods: Patients with schizophrenia (N = 42) were randomly assigned to 2 groups, i.e., intervention (2000 IU of vitamin D daily; n = 21) and placebo groups (n = 21). The intervention was administered for 8 weeks. Anthropometric, clinical, and laboratory measures were assessed at both baseline and end of the trial. The Positive and Negative Syndrome Scale (PANSS) was performed to assess the schizophrenia symptoms.

Results: Vitamin D supplementation leads to a significant decrease in low-density lipoprotein cholesterol (LDL-C) levels (P = 0.006). In addition, a significant improvement was found in the PANSS negative subscale score (PANSS-NSS) and PANSS total score (PANSS-TS; P = 0.005 and P = 0.015, respectively). At the baseline, there was a significant negative correlation between PANSS-NSS, PANSS positive subscale score (PANSS-PSS), and PANSS-TS with serum levels of vitamin D (r = -0.42, P = 0.010; r = -0.34, P = 0.041; and r = -0.47, P = 0.004, respectively).

Conclusions: Vitamin D supplementation may have helpful efficacy on some cardio-metabolic indices and schizophrenia severity.