People who suffer from Vitamin D deficiency are twice as likely to be diagnosed with schizophrenia as those who have sufficient levels of the vitamin, according to new research.
Scientists who examined 19 studies involving more than 2,000 adults found 65% of participants who had the mental health condition were also Vitamin D deficient. Those with schizophrenia had "significantly" lower levels of Vitamin D in their blood compared to those who did not.
People with Vitamin D deficiency were more than twice as likely to have schizophrenia than those with sufficient levels in their blood, according to the study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.
The skin naturally produces Vitamin D after exposure to sunlight and more than a billion people worldwide are thought to have deficient levels of vitamin D because of limited sunshine.
Schizophrenia, with symptoms that can include delusions and hallucinations, is more common in high latitudes and cold climates and researchers had been working on the theory that Vitamin D deficiency could be connected.
"This is the first comprehensive meta-analysis to study the relationship between the two conditions," said one of the research authors, Dr Ahmad Esmaillzadeh of the Isfahan University of Medical Sciences in Isfahan, 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."