Too Much Folic Acid in Pregnancy – is it Linked to Autism?

Folate has been found, in numerous studies, to prevent birth defects including spina bifida. In fact, the introduction of folate into vitamins has correlated with an estimated 1000 less birth defects per year, one of the victories of modern public health initiatives. Today, a study provided some information indicating that although folate is crucial for the early development of babies in the womb – too much folic acid may be a problem as well.

This study followed a group of 1391 children born in Boston University Medical Center – and of this group, 100 children were later diagnosed with autism spectrum disorder. It was found that of those diagnosed, there was an association with higher levels of folic acid in 17 of 100 of these mothers at the time that they gave birth. It’s a small group, but interesting and we should pay attention.

This study was a bit different than most which have been completed on folic acid and birth defects, which have included primarily middle – higher income families. The families in this study were from lower income groups.

First, let’s discuss the incidence of high serum levels of folic acid in these women. Overall this result isn’t surprising, given that a large percentage of people have a genetic mutation known as MTHFR and can’t effectively process folic acid, causing it to linger, unmetabolized in the bloodstream. Autism has already been linked to the MTHFR C677T mutation.

Secondly, consider that synthetic folic acid is added to many processed foods – meaning that those who eat processed foods are exposed to much more on a daily basis.

There is a significant difference between folic acid (synthetic) and natural folate (found in high quality vitamins in the form of L-5-MTHF, or in foods like leafy green raw vegetables and fruit. If you’d like to learn more about that please see this.

Now that you’ve learned the difference between natural folate and synthetic folic acid, let’s go a bit deeper into the study itself.

A Closer Look at the Study

  • People with MTHFR and other mutations in folate metabolism genes do not effectively metabolize the synthetic folic acid that is found in certain vitamins and processed foods. This study measured total folate in the bloodstream, which includes unmetabolized folate. Unmetabolized folate in the bloodstream increases when synthetic folic acid is taken by those with MTHFR mutations, as they are unable to use it effectively. As such,  the autism risk in this study may be increased by having MTHFR itself, and serum folate may be raised due to having the mutation.

  • The addition of synthetic folic acid to processed foods, pasta and bakery products is also potentially involved here. This study was comprised of lower income families, who often don’t consume as much fresh fruit and vegetables (which contain natural bioavailable folates) and tend to consume more packaged and processed foods (containing synthetic folic acid) on the whole. Unfortunately, fresh, healthy produce is much more expensive than processed foods.

    As a result of the widespread addition of folic acid to processed foods, it follows that those who eat more of these foods may have more unmetabolized folic acid in their bloodstreams. So, another question – is it the folic acid, or is it the processed food consumption, or another factor associated with consuming more processed food which is associated with this risk of autism?

To get more accurate answers in a study like this, measuring intracellular folate metabolites would provide more information – do these women have a problem with metabolizing folic acid and getting it into their cells – and therefore it accumulates in the bloodstream?  Differentiating between folate and unmetabolized folate in the blood would also provide more insight. Another factor to consider: synthetic folic acid can block the activity of MTHFR, and reduce the ability of folate to work in the cell.

The Bottom Line From This Study

Numerous studies confirm that folate deficiency in the first trimester increases the risks of neural tube defects and that supplementation with folate (in moderation) is protective against developmental issues. My hope is that this study will not create undue alarm and cause women to avoid taking folate – this is correlation, and not causation – in a very small group of people.

Current evidence strongly points to folate as being protective to fetal development, and preventative for conditions like autism so rather than avoiding it, choose your sources and doses wisely. Moderate amounts of bio-available folates that our cells can readily use – even for those with MTHFR mutations –  are now available in many prenatal vitamins. Avoid processed refined foods and don’t forget to eat your folate-rich leafy green vegetables.

To gain a better understanding of the processes involved in the uptake of folate into the bloodstream and then into the cell, please read here.

1 thought on “Too Much Folic Acid in Pregnancy – is it Linked to Autism?”

  1. Fiona
    Considering that dysbiosis can lead to an increase of anaerobic bacteria increasing both folate and cobalamin and it has been shown those with certain inflammatory bowel diseases have elevated folate couldn’t the elevated methylators be a red herring? I am wondering if the cause of autism is the inflammatory cascade created by gut hyperpermeability.

    Certainly fortification can lead to elevated levels – but I have not seen evidence where high levels can cause an overmethylation – I really think it can be gut issues in the mothers with the higher levels and that is more the cause of the autism. That variable was never looked at in this study.

    George Mandler LDN LicAc FABORM

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