Low levels of vitamin D during pregnancy and breastfeeding have again been linked to the development of autistic-like behaviours.
The link between vitamin D deficiency and autism spectrum disorder (ASD) has long been suspected and a new Australian study published on Wednesday adds to a growing body of evidence.
Researchers at the University of Western Australia and Telethon Kids Institute tested female rats with low levels of vitamin D during pregnancy and lactation.
They found the rats were more likely to have offspring that displayed unusual brain development, impaired cognitive function and altered social behaviour in adulthood.
"For example, offspring of vitamin D deficient mothers had less interest in interacting with an unfamiliar rat, compared to those who had mothers with healthy levels of vitamin D," lead researcher Dr Caitlin Wyrwoll said.
The pups also had difficulty differentiating between familiar and new objects when memory tests were performed.
The Australian study, published in the Journal of Endocrinology, provides further evidence of the importance of maternal vitamin D levels during pregnancy for a baby's brain development, the researchers said.
Differences in social behaviours are a hallmark of ASD, a lifelong developmental condition that ranges in severity and impacts how individuals interact and communicate.
Dr Wyrwoll says the data indicated vitamin D levels may point to a contributing factor in the development of ASD.
"However, further work is needed to establish whether these associations apply to humans," she said.
Vitamin D is not readily available in a diet, and mainly comes from exposure of the skin to sunlight and the effects of ultraviolet B radiation.
Professor Ulrich Schall, Director of the School of Medicine and Public Health at The University of Newcastle says a deficiency in vitamin D may not necessarily cause neurodevelopmental disorders such as ASD, but it appears it makes the brain more susceptible to it.
"It is well known that vitamin D plays an important role in brain development," Prof Schall said.
"Other factors such as a genetic predisposition and life events have also shown to increase risk but can also facilitate resilience."
Associate Professor Darryl Eyles is Head of the Queensland Centre for Mental Health Research Developmental Neurobiology Laboratory at the University of Queensland.
He says supplementation is already recommended during pregnancy in Australia, however, current levels may be too low to be of benefit.
"Given vitamin D is safe and cheap, it may be time to reconsider its use in pregnancy, especially in situations of either deficiency or the presence of known autism risk modifiers," Assoc Prof Eyles said.
Australian Associated Press
