A new study suggests that high iron intake during pregnancy and breastfeeding reduces the risk of autism. The protective effect was clearest among mothers taking iron supplements from the second trimester of pregnancy through breastfeeding.
Overall, the risk of having a child with autism was cut in half for moms who had the highest daily iron intake (over 85 mg) compared to those with the lowest intake (under 30mg).
High versus low iron intake produced an even greater risk reduction – five-fold – among moms older than 35 and those with metabolic conditions such as diabetes, hypertension or obesity. Previous research has shown that autism occurs at higher rates among children born to women in these groups.
The study, by researchers at the University of California-Davis MIND Institute – appears in the American Journal of Epidemiology.
Growing evidence of prenatal influences
“These findings add to the evidence that nutritional factors can have an influence on the development of autism, starting in pregnancy and through breastfeeding,” comments developmental pediatrician Paul Wang, Autism Speaks head of medical research. “This also underscores that the biological processes underlying autism start early – certainly before the first birthday.” Dr. Wang was not involved in the study.
Further research is needed to confirm the findings and to determine optimal iron intake levels that balance benefits against potential toxicity. The doses that appeared most protective in the study – above 85 mg daily – are higher than generally recommended for pregnant women.
Meanwhile, Dr. Wang concurs with the study authors that their findings support the recommendations by the World Health Organization that pregnant and nursing women take supplements containing both iron and folic acid. Ideally, this should begin three months before a woman tries to become pregnant.
CHARGE continues to provide guidance
The new report comes out of the ongoing Childhood Autism Risks from Genetics and the Environment (CHARGE) project. A number of related CHARGE investigations receive support from Autism Speaks – with an emphasis on identifying avoidable autism risk factors. (Learn about these research grants here.)
In 2011, the CHARGE researchers were the first to report that prenatal folic acid appears to reduce risk for autism. Larger investigations supported their findings.
Their new report is the first to look at autism risk and prenatal iron. Participants included 520 mothers of children diagnosed with autism and 346 mothers of children with typical development. Interviewers asked the women to recall their intake of supplements, fortified cereals and other sources of iron from three months prior to their pregnancies through the end of breastfeeding. From this information, the researchers estimated average monthly and daily iron intake for each woman.
"Iron is crucial to early brain development," notes lead author and epidemiologist Rebecca Schmidt. "Iron deficiency, and its resultant anemia, is the most common nutrient deficiency,” she adds. It affects an estimated 40 to 50 percent of American women and infants.
Also see "Risk versus Cause in Autism," by pediatric neurologist Martha Herbert.
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