A randomized controlled trial of Vitamin D supplementation in Iranian patients with schizophrenia: Effects on serum levels of glycogen synthase kinase-3β and symptom severity.

BACKGROUND

Growing evidence has shown that hypovitaminosis D is a risk factor for developing schizophrenia and comorbid conditions. Therefore, this study aimed to examine the effect of vitamin D supplementation on serum levels of vitamin D, metabolic factors related to insulin resistance (IR) and the severity of the disorder in patients with schizophrenia.

METHODS

Forty-eight chronic male patients with schizophrenia with vitamin D deficiency (≤20 ng/mL= (≤50 nmol/l) were selected and randomly assigned to vitamin D treatment and placebo groups. Subjects were supplemented for 8 weeks with vitamin D (2000 IU/day) or placebo.

RESULTS

Within-group comparison revealed that the vitamin D group had a significant reduction in waist circumference, Positive and Negative Syndrome Scale - total score (PANSS-TS), and glycogen synthase kinase 3 beta (GSK-3β) levels ( = .022, = <.001 and = .013, respectively). On the other hand, the placebo group showed a significant increase in the level of fasting serum insulin and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) ( = .003 and = .003). The between-group comparison showed a significant difference in terms of PANSS-TS, GSK-3β, fasting serum insulin (FSI), and HOMA-IR ( = .022, = .048, = .013 and = .014 respectively).

CONCLUSIONS

Among vitamin D deficient patients with schizophrenia, vitamin D supplementation may affect GSK-3 β, an important biomarker in schizophrenia and insulin resistance. In addition, vitamin D supplementation in such patients may reduce the disorder's symptom severity.