People suffering from Vitamin D deficiency are twice more likely to be diagnosed with schizophrenia than those with sufficient levels of it, according to a new study by the Isfahan University of Medical Sciences in Iran.

"When we examined the findings of several observational studies on vitamin D and schizophrenia, we found people with schizophrenia have lower vitamin D levels than healthy people. Vitamin D deficiency is quite common among people with schizophrenia," said one of the study authors, Ahmad Esmaillzadeh, in a press release.

This is the first study to highlight the relationship between the two conditions.

For the study, researchers analysed the results of 19 studies that focused on the link between vitamin D and schizophrenia. The studies examined vitamin D levels and the mental health of 2,804 adult participants. It used blood tests to determine participant's vitamin D levels.

The meta-analysis found that schizophrenic patients were associated with lower levels of vitamin D in the blood compared to the control groups. Plus, 65 percent of the participants suffering from schizophrenia were vitamin D deficient. The average difference in vitamin D levels between schizophrenic and control participants was -5.91 ng/ml.

Researchers also found that Vitamin D deficient participants were 2.16 times more likely to develop schizophrenia than those with adequate levels in their bloodstreams.

"There is a growing trend in the nutrition science field to consider vitamin D and its relationship to conditions such as diabetes, cancer, heart disease and depression," Esmaillzadeh said. "Our findings support the theory that vitamin D may have a significant impact on psychiatric health.

The finding is published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM).