Is too Much Folate during Pregnancy a Bad Thing?

By ProjectManhattan (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons

Women who plan on getting pregnant are told they need to make sure they get enough of the nutrient folate to ensure the proper neurodevelopment of a growing fetus. However, new information from Johns Hopkins Bloomberg School of Public Health suggests there could be serious risks in having high levels of the same nutrient.

The Study

Johns Hopkins researchers found if a new mother has high levels of folate right after giving birth, more than four times what is considered to be adequate, the risk that her infant will develop autism can double. Very high levels of B12 in new mothers also can be very harmful, tripling the risk that he infant will develop autism spectrum disorder. If both the folate and vitamin B12 levels are extremely high, the risk for an infant developing autism increases 17.6 times. Folate, a B vitamin, is naturally found in fruits and veggies, while the synthetic version, folic acid, is used to fortify cereals and breads in the US and in vitamin supplements.

The findings of the study were presented on May 13, 2016 at the 2016 International Meeting for Autism Research in Baltimore.

One of the study’s senior authors, M. Danielle Fallin, PhD, said, “Adequate supplementation is protective. That’s still the story with folic acid. 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 important for cellular growth and it promotes neurodevelopmental growth. Deficiencies in this nutrient in early pregnancy has been linked to birth defects and to an increased risk of developing an autism spectrum disorder. Despite the push to get make sure women who are trying to become pregnant or are already pregnant are receiving adequate amounts, some of them still don’t get enough or their bodies are not properly absorbing it.

When a woman doesn’t get enough folic acid or her body doesn’t absorb it properly, it can lead to deficiencies. The Centers for Disease Control and Prevention says that only one in four women of reproductive age in the United States have sufficient levels of folate. Levels are not routinely tested or monitored during pregnancy.
Autism spectrum disorder is a neurodevelopmental condition that’s highlighted by social impairment, abnormal communication and repetitive or unusual behavior. One in 68 children in the US have autism, with males being five times more likely to have it than a female. The precise causes of autism spectrum disorder aren’t known, but research suggests the factors are a combination of genetics and environment.


With so many different types of vitamin supplements, the conventional thought has always been that too much is not harmful because the body will get rid of the excess. However, that may not be the truth about folic acid and vitamin B12.

Study lead author, Ramkripa Raghavan, MP, and DrPH candidate at the Department of Population, Family and Reproductive Health at the Bloomberg School said, “This research suggests that this could be the case of too much of a good thing. We tell women to be sure to get folate early in pregnancy. What we need to figure out now is whether there should be additional recommendations about just what an optimal dose is throughout pregnancy.”


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