Debunking Folic Acid Misinformation: MTHFR, Autism, and More

There are many nutrients that doctors recommend to support healthy fetal development, but Folic Acid (a form of Folate—more on that shortly) plays a unique role because of its direct contribution to building DNA, the instruction manual for every cell in the body. It’s a critical vitamin in very early pregnancy; cells are dividing at an extraordinary speed as the brain and spinal cord begin to form. Folic Acid helps cells build and copy DNA correctly during this period, and if there isn’t enough, the neural tube may not close properly. That’s why Folic Acid is emphasized more than other vitamins—it’s one of the few nutrients where supplementation has been clearly proven to prevent a specific structural birth defect.

Which is why we need to talk about the current misinformation (that seems to be dominating the prenatal-health conversation) about Folic Acid.

First, some Folic Acid history. In the early 1990s, researchers discovered that supplementing with Folic Acid reduced neural tube defects in newborns by 72%. That reduction was proven in randomized controlled trials—the highest standard of medical evidence. This resulted in the recommendation that all females of childbearing age who could become pregnant consume 400 mcg of Folic Acid daily, and led to the fortification of food with Folic Acid in Canada and the United States. (Fortification is when you add essential micronutrients to foods to improve their nutritional quality. Folic Acid fortification is often found in enriched-grain products like cereals, bread, and pasta.)

A 72% reduction is big, and Folic Acid supplementation and fortification have long been considered an amazing public health win. 

First, it’s important to acknowledge that parents and parents-to-be want the best for their kids, which is increasingly hard given competing information and sensational headlines. If you’re trying to do your best but are confused about the details, we get it, and we’re here to help with research-backed responses fact-checked by doctors.

Because Methylated Folate is easily absorbed, those with a specific gene mutation that may decrease the body’s ability to process Folate as efficiently as others may get more of their dose with the methylated option. 

It’s called the MTHFR gene, and the mutation is actually pretty common. But don’t panic—not all variants affect your ability to process Folate. And even if you do have the mutation that does make it difficult to process Folate, you’re still able to process some Folic Acid into its usable form—just not as much or as easily as your non-MTHFR-gene-carrying counterparts. Studies show that 400 mcg of Folic Acid can still effectively increase blood folate levels, regardless of your genotype. 

There does seem to be some confusion about whether it’s safe to consume Folic Acid if you have the gene mutation, but research shows that Folic Acid is safe to consume, no matter your gene status. So there’s no need to (and you really shouldn’t) opt for a prenatal brand without Folic Acid. Major health organizations agree that Folic Acid at the recommended 400 mcg dose is still the best way to prevent neural tube defects, no matter your gene status.

This one is a bit harder to parse, since it’s rooted in misinformation that spreads like wildfire on the internet. Concern around Folic Acid is about its potential link to Autism, though other concerns linked to miscarriage and tongue-tie incidence are common, too. So let’s take a look at the evidence.

It’s a myth—though a persistent one—that Folic Acid causes autism. The truth is, we don’t know exactly what causes autism, but we do know it has strong links to genetics and parental age. 

We do know that Folic Acid does not cause autism. In fact, multiple studies support that Folic Acid supplementation during critical fetal development windows was associated with healthy brain development and a potential reduction in autism risk. The consensus among major health organizations, including the CDC, FDA, and Health Canada, maintain that Folic Acid is incredibly important in pregnancy (especially early pregnancy), and the protective benefits far outweigh the theoretical risks.

Autism is a neurodivergent condition that has many different experiences and expressions. It’s influenced by genetics, and those with the condition typically process information differently. Characteristics can include challenges with communication, behaviour repetition, and sensory sensitivity.

Another myth—Folic Acid does not cause miscarriage or increase miscarriage risk. In fact, the current evidence supports Folic Acid supplementation to reduce the risk of miscarriage. It’s essential for DNA synthesis and repair which is critical in the first few weeks of pregnancy when exponential cellular division is happening. And we know it prevents neural tube defects, the closure of which happens early in pregnancy, too. Without enough Folic Acid, the risk of miscarriage is higher, especially when it comes to chromosomal abnormalities. 

Unfortunately, the causes of miscarriage are largely unknown, but doctors tend to believe that most fall into one of two categories:

1. The embryo is abnormal (typically a chromosomal issue), or

2. The normal embryo implants into a suboptimal environment (which can be linked to hormonal, structural, or immunity-related issues)

Feeding and early newborn challenges can be extremely stressful, and it’s natural to try to understand why something like a tongue tie has happened. The exact causes of tongue ties are not well understood, though it does appear that genetics play a significant role. But, there’s no sufficient evidence that confirms Folic Acid supplementation causes tongue ties in infants. 

Concerns about a possible link between Folic Acid and tongue tie (ankyloglossia) trace back to one study. In that study, those whose infants had tongue ties reported higher Folic Acid use. But the study wasn’t conclusive and didn’t show a clear cause and effect. It was retrospective (relied on old/existing data), included 225 infants, relied on self-reported supplement use, and had limitations related to study design, potential selection bias, and confounding factors (AKA, other variables that may explain the increase). 

The authors of a 2023 systematic review, which examined 93 articles on the topic of Folic Acid and tongue ties (including that one study above), found that the findings were not consistent across all intake levels, have not been replicated in other populations, and did not demonstrate a clear dose-response relationship. 

The bottom line? There is no high-quality evidence showing that the recommended dose of Folic Acid causes tongue ties, and the well-established benefits of Folic Acid in preventing serious neural tube defects clearly outweigh any unproven concerns.