Taking vitamins early in pregnancy may be key.
Prenatal vitamins may help to lower the risk of autism in children, even for high-risk families.
In prior studies, the use of prenatal vitamins, specifically folate (which is taken as a dietary supplement known as folic acid), has been shown to significantly lower the risk of developing autism spectrum disorder (ASD).
Now, new research published February 27 in
Families that have a child with autism are at high risk of having another child with ASD.
These younger siblings are up to 14 times more likely to have ASD when compared with the general population because of ASD’s genetic heritability.
According to the new study, use of prenatal vitamins cut the risk of developing ASD in younger siblings of children with ASD by half.
“Evidence is building for an important role of gestational exposures, including nutrition, in relation to autism. Research from imaging and other studies of the brain show that processes affected in autism occur during pregnancy. Studies have repeatedly shown that taking folic acid supplements were associated with protection from autism in the general population,”Rebecca J. Schmidt, PhD, assistant professor in the department of public health sciences and the MIND Institute, UC Davis School of Medicine, and first author of the study told Healthline.
Schmidt and her team looked at a cohort of 241 families affected by ASD to see whether prenatal vitamin supplementation offered the same benefits in these high-risk families.
While they found that nearly all mothers — 96 percent — reported taking a prenatal vitamin, only about one third of them took them prior to pregnancy, as recommended.
Mothers who took the vitamins in the first month of their pregnancy were half as likely to have a child diagnosed with ASD.
Mothers who took prenatal vitamins in the first month of pregnancy were also more likely to have children with less severe autism symptoms and higher cognitive scores.
These findings could have important public health implications for the prevention of ASD in future generations, as well as helping to guide future nutritional advice for expecting mothers.
But, there's still more work to do.
“This is a small study that needs to be replicated in a larger sample before true risk reduction calculations and public health policy decisions can be made,” Dr. Kristin Sohl, vice chair of the department of pediatrics at University of Missouri Health Care, and part of Autism Speaks Autism Treatment Network, told Healthline.
Folic acid supplementation, while generally recommended, has not been without criticism.
Research presented by researchers from Johns Hopkins University caused a frenzy in 2016. They found that moms with extremely high levels of folic acid and vitamin B-12 in their blood were linked to an increased autism risk of nearly 18 percent.
Could prenatal vitamins — the very thing mothers were taking to lower the risk of ASD in their children — actually have a role in causing it?
Only in extreme cases.
In their study, women with an increased risk of ASD had levels of folate or B-12 in their blood well in excess of the cutoff recommended by the World Health Organization.
Even the researchers behind those findings concluded that prenatal vitamin supplementation was still a good idea.
Despite the widespread use (and recommendation) of folate supplementation before and during pregnancy, the reasons why it appears to be protective against ASD aren't well understood.
“There are many possibilities. Folate and other vitamins are important for many processes that are critical during development and have been implicated in autism. This includes things like epigenetics — specifically DNA methylation which is dynamic near the critical time implicated in our study and potentially important for fetal programming, DNA synthesis and repair, mitochondrial functioning, oxidative stress, inflammation,” said Schmidt.
Folate is known to help prevent neural tube defects, including spina bifida and anencephaly. It also plays a prominent role in fetal and brain development.
“Because many pregnancies are unplanned and because neural tube defects can develop in the first 28 days of fetal development, all women of child-bearing age are recommended to take increased folic acid,” said Sohl.
Prenatal vitamins containing folic acid (folate) have shown to dramatically decrease the risk of autism spectrum disorder in the general population and certain high-risk families.
Children with older siblings with ASD are statistically far more likely to also have ASD than the general population, so using prenatal vitamins is an important part of care during pregnancy.
Parents should consult with their doctor about appropriate dosing and frequency of these vitamins as excessive amounts of folate have been shown to potentially increase risk of ASD.
“Most prenatal vitamins contain about 800 mcg folic acid, which would be plenty if mothers took one per day. Taking more than this is not recommended,” said Schmidt.