Folic acid is a common supplement found in green leafy vegetables, enriched breads, cereals and grains, and in most prenatal vitamins.
It’s already been proven that consuming folic acid, naturally or in the form of a vitamin, before or soon after becoming pregnant can lower the risk of problems in early stages of brain development. So researchers wanted to see if there was a link between mothers' folic acid intake and the risk of her child developing autism.
Researchers studied thousands of mothers in Norway and asked them to record all of the supplements they were using every day. After their children were born, researchers identified cases of autism occurring among the group.
“The women who took folic acid supplements in early pregnancy had a substantial reduction in risk of having a child with autism. The reduction was 40 percent,” said Pal Suren, MD, MPH, of the Norwegian Institute of Public Health.
But Ezra Susser, MD, DrPH, of the Mailman School of Public Health at Columbia University, says there’s a sensitive period in which folic acid supplements need to be taken in or order to reduce the risk of autism. "The period begins before pregnancy and continues approximately two months after pregnancy," he says.
The Norwegian research also showed that mothers who began taking the supplement at 22 weeks showed no association with lower risk of autism, compared to those who took it in the very early stages of pregnancy.