Vitamin D plays a pivotal role in a number of disorders. Now scientists are investigating whether the ‘sunshine vitamin’ could be implicated in autism. With autism rates climbing and levels of vitamin D declining because of more sunscreen use and less time spent outdoors, scientists have begun to look into a possible link. A recent study in Saudi Arabia was the first to discover that children with autism had significantly lower levels of vitamin D in their bloodstreams than non-autistic children. There is a growing body of literature linking vitamin D to various immune-related conditions, including allergy and autoimmunity, said Laila Y. AL-Ayadhi, a professor of neurophysiology at King Saud University and one of the new study’s lead researchers.
Results of autism studies, however, have been mixed. White house led a study of more than 900 pregnant women that measured Vitamin D at 18 weeks gestation; their children were later assessed for autism. It found no correlation between children’s scores on an autism rating scale and maternal vitamin D levels. But research at the University of California, Davis found an increased risk for children with autism among 700 mothers who did not take prenatal vitamins during the three months before and the first month of pregnancy.
While that study did not specifically call out vitamin D as a suspect, UC Davis researcher Rebecca Schmidt is currently working on a similarly large study that will focus on the importance of maternal vitamin D intake on autism rates. This is the kind of study I think needs to be done where we go back and look at the vitamin D levels in the maternal blood during pregnancy and we follow these children up to see if they’ve developed autism, Schmidt said.
Volk’s research has focused on a possible link between maternal air pollution exposure and autism, but she notes that her findings also could implicate vitamin D. Her study, published in January, found that children with autism were more likely to live in homes that had the highest percent of traffic-related air pollution during their mothers’ pregnancy and the first year of life compared to control children. One explanation is that pollution may induce inflammation in the body that raises the risk of autism.
Air pollution exposure can increase systemic inflammation in the body that really might be affecting the brain, Volk said, adding that vitamin D helps your body deal with inflammation. It helps turn on the body’s responses. Air pollution, studies show, could be acting as a double-edged sword: increasing inflammation and contributing to maternal vitamin D deficiency. Of course pollution isn’t the only reason women are getting less sunlight, and less vitamin D. For decades, women have been avoiding the sun with the help of sunscreens and more time spent indoors. And those decades track with the rising incidence of autism disorders. A 2007 study of 400 pregnant women found that 42.1 percent of white women and 54.1 percent of black women were vitamin D insufficient even though 90 percent of these women took prenatal vitamins.
Yet many questions remain, and experts say none of the research so far has shown a convincing link. Vitamin D is one of many environmental factors, including air pollution and pesticides,that are eyed by researchers seeking to understand why autism rates have continued their uninterrupted climb over the past several decades.