Australasian Science: Australia's authority on science since 1938

Vitamin Deficiency Doubles Schizophrenia Risk

By Stephen Luntz

Important evidence has firmed up the suspected link between vitamin D deficiency and schizophrenia.

Babies in Denmark routinely have blood samples taken at birth, and analysis of these published in the Archives of General Psychiatry shows that those who were deficient in vitamin D have twice the rate of schizophrenia as adults.

The finding is far from a surprise. Evidence for connections between vitamin D deficiency in the latter months of pregnancy and increased risk of schizophrenia has been growing for many years (AS, July 2005, pp.35–38).

Director of the Queensland Centre for Mental Health Research, Prof John McGrath, says that “the evidence is still not conclusive. However, it is much, much stronger now. This is the most direct evidence we have had.”

Nevertheless McGrath warns that the study needs to be reconfirmed with another sample, but this may prove difficult. Denmark was chosen because it had a systematically archived sample with proper privacy controls, but this is lacking in Australia and many other countries.

Moreover, McGrath notes that Denmark is “a good place to do vitamin D deficiency research”. At 55° North, Vitamin D deficiency is common in winter and early spring.

The majority of schizophrenia cases occur in people who were not vitamin D-deficient at birth. McGrath says that this is because “schizophrenia is not one disease; there are probably hundreds or thousands of causes. It is like fever.”

However, researchers of other diseases have suggested that the levels at which vitamin D concentration in the blood is considered deficient may be too low. McGrath agrees that recommended levels need to be reviewed.

“We don’t know what the optimal range is for brain growth,” he says. “The levels were based on bone diseases where vitamin D is the big hit, but it may be that for conditions like this, where it is just one factor, the levels are inadequate.”

Many questions remain unanswered, including whether the effect is entirely based on prenatal deficiency or whether low intake in early childhood is also significant. McGrath refers to a Finnish study where male children whose mothers said they had not given them vitamin D supplements in the first year of life were more likely to suffer schizophrenia, but says that far more research is needed.

Whatever the uncertainties in regards to brain development, McGrath says it is clear that many pregnant women are getting so little sunlight that their children’s bone development is in danger.