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If you’re planning to get pregnant, one of the first things your doctor will tell you is to take a daily prenatal vitamin with folic acid. That’s because folic acid — the synthetic form of folate, or vitamin B9 — has been shown to help prevent neural-tube defects, including anencephaly and spina bifida. In a healthy pregnancy, the neural tube forms in the early weeks of gestation, eventually developing into the brain and spinal cord. If the neural tube doesn’t close properly, the results can be catastrophic. Many of these pregnancies end in miscarriage or stillbirth. In other cases, babies are born missing parts of the brain and skull and die within days of being born. Those who do survive are likely to contend with a wide range of serious disabilities, including paralysis.

The World Health Organization estimates that around 300,000 babies are born with neural-tube defects each year. However, in many cases these birth defects are preventable with folic-acid supplementation. In fact, folic acid is so effective at preventing neural-tube defects that since 1998, the U.S. has required that it be added to certain “enriched” grain products — including flour, bread, pasta, and breakfast cereal — to help ensure that women who become pregnant are getting enough of it. According to the CDC, fortifying grains with folic acid helps prevent around 1,300 babies from being born with neural-tube defects every year.

Supplements are a gigantic industry, despite the fact that, in most cases, they don’t do much for our health. Folic acid is a rare exception. Adding it to everyday foods has saved lives. But lately, as wellness influencers grow increasingly suspicious of the synthetic chemicals lurking in our food supply, many of them have turned on folic acid. Instagram is full of videos warning that folic acid is toxic, blaming it for everything from miscarriages to autism — and supplement companies are lining up to sell women an unproven alternative. Now, a growing number of popular brands — including Ritual, Thorne, Needed, and Perelel — are selling prenatal vitamins that don’t include folic acid at all.

Appearing on The Skinny Confidential Him and Her podcast earlier this year, the biohacker Gary Brecka told co-hosts Lauryn and Michael Bosstick that prenatal vitamins containing folic acid are “the leading cause of postpartum depression.” A few months later, Bosstick, pregnant with her third child, posted a video gushing about Ritual’s prenatal vitamins, noting that, instead of folic acid, their formulation includes “a specific methylated form” of folate that Brecka recommends to avoid postpartum depression and anxiety. She’s not the only one. Influencers like Hannah Bronfman and Danielle Brown (also known as Healthy Girl Kitchen) swear by Ritual’s prenatal vitamins, and Serena Williams recently joined the company as a “Women’s Health Advisor.” “Ritual has been challenging industry norms since day one,” Williams said in a promo video, adding that she “trusts the products” because they’re “backed by science.”

In their marketing copy, Ritual and its competitors claim that folic acid is an inferior form of folate because it’s synthetic. Instead of folic acid, these brands use methylfolate. Both folic acid and methylfolate are forms of folate, a nutrient found in leafy green vegetables and legumes. Typically, when you consume folic acid, your body converts it into methylfolate through a process called methylation. Ritual argues that because methylfolate has already been chemically reduced to the “active form” of folate, it’s a better choice — especially since, it claims, “up to one-third of adults have a genetic variation that makes it difficult to efficiently utilize folic acid.”

This is where things get even more confusing and contentious. For the pro-methylfolate camp, everything comes back to MTHFR gene variants. This isn’t new: Over the past 15 years, as direct-to-consumer genetic tests have become more popular, alternative-medicine practitioners have seized on MTHFR variants as a catchall diagnosis, claiming they’re responsible for everything from infertility and pregnancy loss to ADHD, OCD, bipolar disorder, hypertension, thyroid disease, and poor gut health. The naturopathic doctor Ben Lynch helped pave the way for this, claiming that if you have an MTHFR gene variant — or as he likes to call it, “mutation” — your body can’t metabolize folic acid. Conveniently, he had a solution. In 2011, he founded Seeking Health, a supplement company that sells a vast array of vitamins designed to be “bioavailable” for people with MTHFR variants — and one of the first to market a prenatal vitamin using methylfolate instead of folic acid.

According to 23andMe, MTHFR is the “most-asked about gene” by customers. That’s probably because variants of this gene are incredibly common; according to the CDC, more than half the population has one. And while they have become fertile ground for speculation and medical misinformation, there’s no definitive evidence that they cause any significant health effects, says Shannon M. Clark, an OBGYN and maternal-fetal medicine specialist. For that reason, medical organizations generally recommend against testing for MTHFR variants. The OBGYN Jen Gunter has called MTHFR testing “meaningless” and “a scam.”

That said, having an MTHFR variant does impact how your body processes folate — it just means that, because you’re more likely to have lower blood-folate levels, you need more folic acid to protect against neural-tube defects, according to Martha Field, a professor of nutrition at Cornell.

There’s also no credible evidence that consuming folic acid at the recommended dosage has any negative effects on health. While some influencers claim that taking folic acid increases the chance of miscarriage, studies show the opposite. And contrary to what Brecka says, studies show that folic-acid supplementation helps reduce perinatal depression symptoms, too. While supplement companies that use methylfolate like to emphasize the risks of taking too much folic acid, the amount added to fortified foods is actually pretty conservative. Evidence shows most people consume less than 150 micrograms of folic acid a day from fortified food. Unless you’re taking multiple supplements that contain folic acid, it’s unlikely you’d exceed the recommended limit, says Field.

The problem with replacing folic acid in prenatal vitamins is that there haven’t been any clinical trials showing that methylfolate prevents neural-tube defects, Field says. According to the CDC, folic acid is the only form of folate that has been proven to help prevent neural-tube defects. It’s so effective that doing a trial comparing the efficacy of folic acid and methylfolate in early pregnancy would be unethical “because you can’t withhold folic acid from a pregnant woman,” says Field. While Ritual claims to be “the only leading prenatal backed by its own human clinical trial,” that trial had only 62 participants and it hasn’t been published in a journal. Ritual also didn’t exactly show that its vitamin prevents neural-tube defects, because it looked only at women in the second and third trimester of pregnancy — after the neural tube has already closed, says Kevin C. Klatt, a metabolism researcher at the University of California, Berkeley. (Ritual declined to comment for this story, and none of the other supplement companies mentioned in this story responded to a request for comment.)

Ritual suggests that because methylfolate has been shown to raise blood-folate levels, it would presumably support neural-tube development, which happens in the first month of pregnancy. “That’s a totally valid hypothesis, but they haven’t shown that,” says Klatt. And there are reasons to be skeptical that’s the case. Folic acid is much more chemically stable than methylfolate, says Klatt. It holds up well in food and supplements, and it’s actually more bioavailable than folate found in food. On the other hand, methylfolate degrades more easily when it’s exposed to light and oxygen. “So when you put a certain amount of methylfolate in a bottle of prenatal vitamins, you don’t know how much a patient is getting,” says Clark.

Methylfolate is also more expensive. Ritual spins this into a selling point to help justify the fact that it charges three times as much as supermarket prenatals. “They have the beautiful website and the beautiful marketing, and they can make all these bullshit claims because there’s no regulation,” says Clark. Because the FDA classifies prenatal vitamins as dietary supplements, they are not required to include certain ingredients, nor are they evaluated for safety or effectiveness before they hit the market.

“These brands are preying on the fact that people don’t trust institutions or official recommendations, and then they’re selling the solution,” Klatt believes — and if that’s the intent, it appears to be working. Ritual made more than $250 million last year, and its prenatals routinely make it into popular roundups of “best prenatal vitamins,” which neglect to mention that they don’t include the only ingredient that has been shown to prevent neural-tube defects. Clark says she sees patients all the time who are taking a fancy prenatal vitamin without realizing it isn’t what their doctor would recommend.

The risk of having a pregnancy affected by a neural-tube defect is low, Klatt says, and many women don’t start taking a prenatal vitamin until after they find out that they’re pregnant — and after the crucial window for neural-tube development — which is why the U.S. fortifies grains with folic acid. “But now you’ve got trad moms making TikToks about how they’re making bread that’s folic-acid free,” Klatt says. As folic-acid misinformation spreads online, “it’s making the everyday mom turn away from what’s probably the most evidence-based thing in maternal child nutrition — and have to shell out tons of money.” Any case of a neural-tube defect that could have been prevented is a tragedy. “We know folic acid works. We have the evidence,” says Clark. “Why take that risk?”

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