Women who take the recommended amount of folic acid around conception might reduce their child’s risk of pesticide-related autism, according to a new study published in the journal Environmental Health Perspectives.
In the study, children whose mothers took 800 or more micrograms of folic acid (the amount in most prenatal vitamins) had a significantly lower risk of developing autism spectrum disorder (ASD), even when their mothers were exposed to household or agricultural pesticides associated with increased risk.
“We found that if the mom was taking folic acid during the window around conception, the risk associated with pesticides seemed to be attenuated,” said first author Dr. Rebecca J. Schmidt, assistant professor in the Department of Public Health Sciences at the University of California (UC) Davis.
“Mothers should try to avoid pesticides. But if they live near agriculture, where pesticides can blow in, this might be a way to counter those effects.”
Using data from the Childhood Autism Risks from Genetics and the Environment (CHARGE), the researchers looked at 296 children between ages two and five who had been diagnosed with ASD as well as 220 who had developed typically.
Mothers had reported on their household pesticide exposure during pregnancy, as well as their folic acid and B vitamin intake. The researchers also used data from California Pesticide Use reports, which provide important details about agricultural spraying and linked it with the mothers’ addresses.
Mothers who took less than 800 micrograms and encountered household pesticides had a much higher estimated risk of having a child who developed an ASD than those who took 800 micrograms of folic acid or more and were not exposed to pesticides. The associated risk increased for women exposed repeatedly.
Mothers with low folic acid intake who were exposed to agricultural pesticides during a window from three months before conception to three months afterward were also at greater risk.
“Folic acid intake below the median and exposure to pesticides was associated with higher risk of autism than either low intake or exposure alone,” said Schmidt, a University of California, Davis MIND Institute faculty member. “The mothers who had the highest risk were the ones who were exposed to pesticides regularly.”
Although folic acid did lower the associated risk of a child developing autism, it did not entirely stop it.
“It would be better for women to avoid chronic pesticide exposure if they can while pregnant,” Schmidt said.
The researchers warn that this is a case-control study that had to rely heavily on participants’ memories. Further, they have yet to establish a causal link. However, the findings certainly warrant larger studies to confirm them. The team is also eager to look into the mechanisms that underly folic acid’s possible protective effects.
“Folate plays a critical role in DNA methylation (a process by which genes are turned off or on), as well as in DNA repair and synthesis,” said Schmidt. “These are all really important during periods of rapid growth when there are lots of cells dividing, as in a developing fetus. Adding folic acid might be helping out in a number of these genomic functions.”