Prenatal Folic Acid Linked to Lower Risk of Autism

By Theresa Waldron, author of

The puzzle of what causes the lifelong mental condition called autism has eluded researchers for decades. Autism, a disorder which can lead to developmental delays, trouble communicating,  and difficulty forming relationships, is now found in one in 88 American children. The lifetime estimated costs associated for caring for someone with autism range from $1.46 million to $2.4 million, depending on the severity of the person’s condition.

First there was a theory that autism was caused by childhood vaccines; this has now been debunked by dozens of large epidemiologic studies. Other promising research points to genetic causes, but much complex research is still needed to sort it out. Some believe autism is caused by exposure to “environmental toxins” such as mercury and other harmful substances.

But a new study from the Norwegian Institute of Public Health in Oslo of more than 85,000 children indicates the nutrient folic acid may play a role in development of autism. A 2012 study from the University of California Davis School of Medicine found similar results. Folic acid (called “folate”) is a B vitamin that helps the body make healthy new cells. It can be difficult to get all the folic acid you need through your diet alone.

Folic Acid Taken Before Pregnancy

Researchers evaluated women who took folic acid supplements from four weeks before pregnancy to eight weeks after pregnancy, which is a critical time for brain development in the fetus. Their babies were found to have a considerably lower risk of autism. The study appears in the Feb. 13 issue of the Journal of the American Medical Association.

This is not the first time that folic acid has been found to prevent a neurodevelopmental disorder. Similar studies in the 1980s indicated that folic acid supplements taken during pregnancy helped prevent “neural tube defects,” in babies. Neural tube defects are birth defects better known as spina bifida and anencephaly, which cause the incomplete development of the spinal cord or its coverings.

The findings of the neural tube defects/folic acid studies were so compelling that the Centers for Disease Control and Prevention in 1991 began officially recommending that pregnant women or women trying to conceive take folic acid supplements as a way to prevent spina bifida and anencephaly in their babies.

Three Groups of Children Studied

In the latest autism study, researchers looked at children around ages three to 10 who had autism and who had been born to mothers who took folic acid before and during pregnancy. In all, 270 children (0.32 percent) were diagnosed with some type of autism.

The researchers broke the types of autism into three groups: those with autistic disorder, or “classic autism”; those with Asperger syndrome; and those with PDD-NOS (pervasive-developmental disorder – not otherwise specified). Asperger syndrome and PDD-NOS are considered subcategories of autism, and tend to be associated with higher intellectual ability. (There are two other types of autism: Rett’s disorder and childhood disintegrative disorder). However, all people with autism tend to share similar characteristics, such as problems communicating and having “repetitive” behaviors, such as hand flapping.

There was an “inverse,” or opposite, association found between the children whose mothers took folic acid during pregnancy and being born with autistic disorder. However, there was no substantial association found with Asperger syndrome and PDD-NOS among children of mothers who took folic acid.

Lower Odds Linked to Supplement

Overall, autistic disorder occurred in 0.10 percent of children whose mothers took folic acid compared to 0.21 percent in children whose mothers did not take the supplement. The children born to mothers taking the supplement had a 39 percent lower odds of having autistic disorder than the children born to mothers not taking the supplement.
The researchers conclude that the “main finding” of the study was that the mothers had to have taken folic acid supplements close to conception – not sometime in the past, or later in pregnancy. The researchers also caution that their “finding does not establish a causal relation between folic acid use and autistic disorder” and that further studies are needed.
The usual recommended dose of folic acid is 400-800 mcg daily. Most multivitamin supplements (prenatal supplements in particular) contain this amount of the nutrient.
Foods high in folic acid are:

  • beans and peas
  • dairy products
  • poultry and meat
  • eggs
  • seafood
  • grains
  • vegetables (especially dark green leafy vegetables)
  • fruits and fruit juices
  • nuts

Foods with the highest folic acid level are spinach, liver, yeast, asparagus, and Brussels sprouts.


For more information on autism, visit
“Autism Science Foundation” at:
“Autism Speaks” at:

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