Too much folate in pregnant women increases risk for autism, study suggests

http://www.eurekalert.org/pub_releases/2016-05/jhub-tmf050916.php

Public Release: 11-May-2016
Too much folate in pregnant women increases risk for autism, study suggests
Researchers say that while folate deficiency is bad for developing fetus, excessive amounts could also be harmful
Johns Hopkins University Bloomberg School of Public Health

Women who plan on becoming pregnant are told they need enough of the nutrient folate to ensure proper neurodevelopment of their babies, but new research from the Johns Hopkins Bloomberg School of Public Health suggests there could be serious risks in having far too much of the same nutrient.

The researchers found that if a new mother has a very high level of folate right after giving birth - more than four times what is considered adequate - the risk that her child will develop an autism spectrum disorder doubles. Very high vitamin B12 levels in new moms are also potentially harmful, tripling the risk that her offspring will develop an autism spectrum disorder. If both levels are extremely high, the risk that a child develops the disorder increases 17.6 times. Folate, a B vitamin, is found naturally in fruits and vegetables, while the synthetic version, folic acid, is used to fortify cereals and breads in the United States and in vitamin supplements.

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"Adequate supplementation is protective: That's still the story with folic acid," says one of the study's senior authors M. Daniele Fallin, PhD, director of the Bloomberg School's Wendy Klag Center for Autism and Developmental Disabilities. "We have long known that a folate deficiency in pregnant mothers is detrimental to her child's development. But what this tells us is that excessive amounts may also cause harm. We must aim for optimal levels of this important nutrient."

Folate is essential in cell growth and promotes neurodevelopmental growth. Deficiencies early in pregnancy have been linked to birth defects and to an increased risk of developing an autism spectrum disorder. And despite this push to ensure women get adequate folate, some women still don't get enough or their bodies aren't properly absorbing it, leading to deficiencies. The Centers for Disease Control and Prevention says that one in four women of reproductive age in the U.S. have insufficient folate levels. Levels are not routinely monitored during pregnancy.

Autism spectrum disorder is a neurodevelopmental condition characterized by social impairment, abnormal communication and repetitive or unusual behavior. One in 68 children in the U.S. have the disorder, with boys five times more likely than girls to have it. The causes remain unclear but research suggests the factors are a combination of genes and the environment.

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A large majority of the mothers in the study reported having taken multivitamins - which would include folic acid and vitamin B12 - throughout pregnancy. But the researchers say they don't know exactly why some of the women had such high levels in their blood. It could be that they consumed too many folic acid-fortified foods or took too many supplements. Or, they say, it could be that some women are genetically predisposed to absorbing greater quantities of folate or metabolizing it slower, leading to the excess. Or it could be a combination of the two.

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With many types of vitamin supplements, the conventional wisdom has been that too much is not harmful, that the body will flush out the excess. That may not be the case with folic acid and vitamin B12.

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