Researchers at The University of Queensland's Queensland Brain Institute have found a link between vitamin D deficiency in pregnancy and increased autism traits.
The study, led by QBI researcher Professor John McGrath and involving Dr Henning Tiemeier from the Erasmus Medical Centre in The Netherlands, found that pregnant women with low vitamin D levels at 20 weeks' gestation were more likely to have a child with autistic traits by the age of six.
"This study provides further evidence that low vitamin D is associated with neurodevelopmental disorders," Professor McGrath said.
"Just as taking folate in pregnancy has reduced the incidence of spina bifida, the result of this study suggests that prenatal vitamin D supplements may reduce the incidence of autism."
While it is widely known that vitamin D is vital for maintaining healthy bones, there is now a solid body of evidence linking it to brain growth.
vitamin D usually comes from exposure to the sun, but it can also be found in some foods and supplements.
The study examined approximately 4200 blood samples from pregnant women and their children, who were closely monitored as part of the long-term "Generation R" study in Rotterdam, The Netherlands.
"This research could have important implications from a public health perspective," Professor McGrath said.
"We would not recommend more sun exposure, because of the increased risk of skin cancer in countries like Australia.
"Instead, it's feasible that a safe, inexpensive, and publicly accessible vitamin D supplement in at-risk groups may reduce the prevalence of this risk factor."
Autism – or autism spectrum disorder - is used to describe lifelong developmental disabilities including an inability to communicate with others, interact socially, or fully comprehend the world.
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A A E Vinkhuyzen et al. Gestational vitamin D deficiency and autism-related traits: the Generation R Study, Molecular Psychiatry (2016). DOI: 10.1038/mp.2016.213