Vitamin D as a Modifiable Risk Factor in Schizophrenia a Systematic Review

The etiology of schizophrenia remains poorly understood. Although certain risk factors have been identified, effective preventive measures are still lacking. This study investigates potential preventive methods while focusing on the role of vitamin D and its status. The role of malnutrition in schizophrenia risk was first identified in studies on the Dutch Hunger Winter. Vitamin D deficiency was hypothesized as a contributing factor shortly thereafter. This review aims to explore the correlations between vitamin D deficiency at various life stages (maternal, neonatal, adult) and schizophrenia risk, as well as its effects on pharmacokinetics, neurobiology, bone health, and metabolic syndrome. The studies were retrieved from two indexed databases, PubMed and Web of Science, following PRISMA guidelines and included studies published between 2000 and 2024. No correlation was found between maternal vitamin D levels and schizophrenia in offspring while a positive correlation was observed between low neonatal vitamin D levels and schizophrenia in later life. Approximately half of the studies on adults reported mean vitamin D concentrations of below 20 ng/mL which were negatively correlated with gray matter volume and bone health while positively correlated with the prevalence of metabolic syndrome. Additionally, vitamin D levels were also found to correlate with antipsychotic drug concentrations.