QUEENSLAND, Australia — Research has shown that vitamin D helps prevent osteoporosis in older adults, and can also reduce the risk of diabetes and cancer, among other life-threatening illnesses. But to date the so-called “sunshine” vitamin has received far less public health emphasis than vitamins C and E.

Now, two recent studies – one with humans, the other with lab mice — suggest that the long-neglected supplement can also help reduce the threat of a baby being born with autism, a neuro-developmental disorder that affects 1 in 45 children.

The human study — conducted jointly by the Brain Institute at the University of Queensland in Australia and the Erasmus Medical Center in The Netherlands – compared mothers with autistic children to those with neurotypical offspring.

The study examined approximately 4,200 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.

The mothers of autistic children displayed a significant vitamin D deficiency, suggesting that the two conditions were somehow correlated.

A follow-up experiment at the University of Queensland by Prof. Darryl Eyles, who co-directed the human study, tested the effect of vitamin D injections on pregnant mice to determine if their progeny were less likely to develop symptoms of autism.

“Our study used the most widely accepted developmental model of autism in which affected mice behave abnormally and show deficits in social interaction, basic learning and stereotyped behaviours,” Eyles said in a news release. “We found that pregnant females treated with active vitamin D in the equivalent of the first trimester of pregnancy produced offspring that did not develop these deficits.”

Medical professionals disagree on the wisdom of injecting pregnant mothers with high doses of vitamin D because the chemical composition of supplements differs from the vitamin D that humans typically receive from natural sunlight. An overdose of vitamin D supplements, which also strengthen bone density, could damage the vulnerable skeleton of the fetus and lead to birth defects, some say.

As a result, a promising new prenatal autism prevention treatment may still be a ways off.

“Recent funding will now allow us to determine how much cholecalciferol – the supplement form that is safe for pregnant women — is needed to achieve the same levels of active hormonal vitamin D in the bloodstream,” says Dr. Wei Luan, a postdoctoral researcher who assisted Prof. Eyles with the mice study.

“This new information will allow us to further investigate the ideal dose and timing of vitamin D supplementation for pregnant women,” Luan adds.

Vitamin D deficiency during pregnancy has been linked to many different health conditions including schizophrenia, asthma, and eczema.

“What we know is that vitamin D during pregnancy is very important for how the baby develops,” said autism and child development expert Andrew Whitehouse in a separate interview.

The results of the human study were published in the November 2016 issue of Molecular Psychiatry. The mice study findings appeared in the most recent issue Molecular Autism.