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Dr. Tori Hudson, Portland, Oregon, Blog Healthline Blog

It has been known for some time now that folic acid supplementation during pregnancy can protect against neural tube defects. More recently though, there is some evidence that it may be associated with lower occurrences of other neurodevelopmental disorders. In the current study, researchers used data from a nationwide Norwegian group of > 85,000 children born during a 10 year period in order to explore the possible association between periconceptional folate intake and autism spectrum disorders. (ASDs).

Autism awarenessASDs were diagnosed in 0.32% of the children. Questionnaires reported maternal folic acid supplementation varied from 33% using it before conception, 71% during weeks 9-12 of pregnancy and 46% during weeks 13 to 16. The most severe form of ASD, autistic disorder, was present in 0.10% of children who mothers used folic acid supplements from 4 weeks pre-pregnancy to week 8 of the pregnancy and in 0.21% of children whose mothers did not take folic acid. In the analysis, neither folic acid supplementation during week 22 nor periconceptional fish oil supplementation affected risk for autistic disorder and folic acid use was not significantly associated with Asperger syndrome or other autism spectrum disorders.

Commentary: Sadly, the incidence of autism spectrum disorders is rising and we have only little understanding of why, and how to prevent it. This observational study supports the notion that the benefits of folic acid before and during pregnancy may be helpful in prevention beyond neural tube defects. In women who took the folic acid for one month before and 8 weeks into the pregnancy, they gave birth to half as many children with ASD as those women who did not take any. Folic acid later in pregnancy or fish oil before and during pregnancy, appeared to have no impact for this issue. Given the incredible inexpensive costs of folic acid supplementation, this continues to be one of the most important periconception and pregnancy vitamin for women to take. This nutrient should be in all prenatal vitamins.

Currently, the average intake of folic acid from the diet of women of childbearing age is about 170mcg/day. A diet without folic acid fortified grains is typically 140 mcg/day. Clearly, too few women are achieving adequate serum folate levels through diet alone and do require supplementation. The RDA for folate in non-pregnant women is 400 mcg per day. The RDA for folate in pregnancy is 600 mcg per day although the latest US Preventive Services Task Force recommendation is 400mcg-800 mcg per day for women of childbearing age. The American College of Obstetricians and Gynecologists recommends that non pregnant women of childbearing aged consume 400 mcg/day. This variability reflects the uncertainty about the exact dose that is optimal for the prevention of neural tube defects. For women with a previous pregnancy resulting in a neural tube defect, 4,000 mcg is necessary to achieve these prevention benefits.

Women with a known genetic defect in folic acid absorption, should look for prenatal vitamins with the already converted form of folic acid, called methylfolate or L-methylfolate or MTHF.


Suren P, et al. Association between maternal use of folic acid supplements and risk of autism spectrum disorders in children. JAMA 2013. Feb 13;309:570

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