Folic acid is the best choice for a healthy pregnancy

When you’re pregnant, you’re going to do everything you can to give your baby the best start possible. That’s why it’s so frustrating when influencers and companies sell you lies about folic acid... and then try to sell you supplements that they claim are better. So how do we know that folic acid is important? Are we sure that it doesn’t cause cancer, autism, or depression? What about that tricky MTHFR gene variant? Here’s what you need to know to make a good decision about folic acid for you and your baby.

Folate and folic acid 101

Folate, or vitamin B9, is found in many foods, including dark green leafy vegetables, asparagus, brussels sprouts, oranges, walnuts, and beans.

Although you might hear folate and folic acid used interchangeably, they’re not exactly the same. Folate is an umbrella term that describes all forms of vitamin B9, and people often use it to refer to the version found in food. Folic acid refers to a synthetic, stable form of folate that is used in supplements or added to food. It’s also the form that’s been studied most thoroughly, precisely because it’s stable. (That means it can stand up to heat and light exposure. It even remains stable through cooking and baking.)

Whether we’re talking about folate or folic acid, the vitamin plays a key role in how cells grow and divide. “Our cells turn over all the time,” says Marian Neuhouser, a nutritional epidemiologist and leader of the Cancer Prevention Program at the Fred Hutchinson Cancer Center in Seattle. And replacing them requires DNA, the genetic instructions for your body. “[Folate] helps make precursors for DNA synthesis,” explains Neuhouser. That’s why it’s especially important for anyone who is pregnant or can become pregnant.

Why folic acid is critical during pregnancy

During pregnancy, the body needs more folate than usual. In the early stages, “those cells are replicating really fast in the embryo, and you need the precursors for DNA to make the cells,” says Neuhouser. The consequences of insufficient folic acid during pregnancy are serious. In the first 28 days after conception, the vitamin helps to form the neural tube, which becomes the baby’s brain and spine. If it doesn’t form correctly, the baby may be born with a neural tube defect like spina bifida (when the neural tube doesn’t close all the way, leading to incomplete formation of the spinal cord) or more-serious anencephaly (when the top of the neural tube doesn’t close, resulting in parts of the brain not forming and, in almost all cases, miscarriage or death shortly after birth).

In the 1960s, researchers noticed a link between low blood levels of folate in the birthing parent and babies born with neural tube defects. But those studies couldn’t prove that low folate levels caused the defects. (Something else about the parents or babies might have explained the results.)

But since those initial findings, results from randomized controlled trials have conclusively established that taking folic acid supplements early in pregnancy reduces the risk of neural tube defects. In one of those trials—it recruited 1,817 people who had previously given birth to a child with a neural tube defect, so they had a high risk of a second pregnancy with the same result—folic acid reduced the risk by 72 percent. In fact, the trial was so successful that it was halted early because the outcome was already clear and continuing would not have been fair for the people who weren’t receiving folic acid.

In 1992, the United States Public Health Service recommended that anyone capable of becoming pregnant should consume 400 micrograms of folic acid every day (in addition to the folate they were getting from food) to prevent neural tube defects, whether or not they were planning a pregnancy. That’s because many people don’t find out that they are pregnant until at least a month after conception, and roughly 40 percent of pregnancies are unplanned. That recommendation, which is still in place today (though it currently stands at 400 to 800 micrograms a day), has been echoed by the American College of Obstetricians and Gynecologists, American Academy of Family Physicians, and American Academy of Pediatrics.

Why are those recommendations specifically for folic acid, and not more broadly for folate? Because the randomized trials used folic acid. Folate will probably never be tested. “This is a case where a trial is not always the most ethical choice,” says Neuhouser. Why? The evidence that folic acid prevents neural tube defects is so solid that it would be unethical to assign pregnant people to take a placebo or folate. 

Folic acid fortification in the United States 

Efforts to prevent neural tube defects didn’t stop with the 1992 recommendation for anyone who can become pregnant to take folic acid. In 1998, the FDA required companies to add folic acid to all “enriched” grains, including any bread, pasta, rice, cereal, flour, or other grain product that’s marketed as “enriched.” (“Enriched” grains were already being fortified with iron and three other B vitamins: thiamin, riboflavin, and niacin.) The results were conclusive: Folic acid fortification has prevented an estimated 1,300 neural tube defects every year. 

How much folate do I need? Should I take a supplement?

How much folate you need—and whether you’ll need a supplement to get there—depends on your age and whether you’re pregnant or could become pregnant.

In the tables below, you’ll see the term “DFE.” It stands for “dietary folate equivalents,” which reflects the fact that your body absorbs folic acid more readily than folate, so you need less folic acid than folate to hit your daily targets. For example, 240 micrograms of folic acid and 400 mcg of folate are both equal to 400 mcg DFE. (To convert from micrograms of folic acid to micrograms of DFE, multiply by 1.7.) 

Recommended Daily Targets 

Foods with folate 

If you’re not pregnant and know that you’re not going to get pregnant, there are plenty of ways to get the folate you need from food. Here’s how much occurs naturally in some top sources. The last column shows the percent of the Daily Value (DV), which is equal to 400 mcg of Dietary Folate Equivalents (DFE)

Source: USDA Food Data Central. 

Grains with added folic acid

Here’s how much folic acid is added to some common grains. The last column shows the percent of the DV, which is equal to 235 mcg of folic acid.  

Sources: company information, NIQ Product Explorer, USDA Food Data Central. 

What if you’re pregnant or thinking about getting pregnant and your diet is already high in folate? Great! But you still should take a prenatal multivitamin that contains enough folic acid, since that’s the only form that’s been proven to reduce the risk of neural tube defects. There’s low risk of harm. (The primary concern is that too much folic acid might hide a vitamin B12 deficiency that can lead to permanent damage to the brain, spinal cord, and nerves.) To play it safe, though, you should avoid taking more than 1,000 micrograms a day. (Note: Folate that’s naturally present in food isn’t harmful.)

Which is more bioavailable—folic acid or folate?  

Some prenatal vitamins that contain folate rather than folic acid claim that folate is more bioavailable. Although it’s true that folic acid is synthetic, that doesn’t make it less bioavailable.

“Bioavailability refers to the ability of a human body to break down and absorb nutrients,” explains Neuhouser. She notes that folic acid is directly absorbed and available to a growing fetus. And 85 to 100 percent of the folic acid in supplements or fortified foods is bioavailable (you’ll absorb more if you take it on an empty stomach), while the folate that naturally occurs in foods is between 44 and 80 percent bioavailable. Translation: Folic acid is more bioavailable than folate.

Judy Simon, a registered dietitian specializing in reproductive nutrition at the University of Washington Medical Center, counsels her patients who are trying to get pregnant to take at least 400 micrograms of folic acid from a supplement every day. In fact, clinicians often recommend a higher dose to people who are at increased risk of birth defects in pregnancy. What’s more, notes Simon, “newer research has shown that for women going through in vitro fertilization, perhaps even 800 micrograms may be more helpful, not just to prevent neural tube defects, but to help with fertility.” She also tells her patients that there’s no reason to think that folate is better than folic acid because it’s found naturally in foods. “At the end of the day, your body has no idea if something is synthetic or came from food,” she says.

What should I take if I have an MTHFR variant?

The MTHFR gene provides instructions for your body to make the protein that helps you process folate. While everyone has two copies of the gene—one from each parent—some people have variants (that is, a change in the gene’s DNA sequence). Variants in MTHFR are common and normal. In fact, most people in the US have at least one copy of one of the most common MTHFR gene variants.

Some prenatal vitamins claim that people with an MTHFR variant need to take a vitamin that contains a version of folate called L-methylfolate, or 5-MTHF. Why? Folic acid has to undergo conversion before becoming the active form that the body can use, whereas 5-MTHF doesn’t require conversion.

Sounds important. But it doesn’t matter. People with the variant can still process folic acid without any problems. “When getting the same amount of folic acid, people with the [variant] have an average amount of folate in their blood that is only slightly lower” than people without the variant, says the CDC.

But that doesn’t stop influencers and supplement companies from pushing supplements with folate instead of folic acid.

“If you have MTHFR, you need to listen up, because this has folate instead of folic acid,” says one influencer, waving a bottle of prenatal vitamins in a post marked “eligible for commission.” (That means she makes money if you buy it.) “Your body cannot break down folic acid. It only can do folate.”

Another influencer, who just happens to sell a genetic test that will purportedly determine if you have the variant, blames the gene for everything from autism to colon cancer to anxiety. And another says that having the variant means “your detox pathways are going to run a little slower.” 

Not a single one of those claims is true.

It’s not just influencers who are trying to make money off false claims about the MTHFR gene. Supplement companies are in on it, too. Take Ritual, which sells a prenatal vitamin that contains 5-MTHF instead of folic acid. (A 30-day supply will run you about $39, compared to just $27 for an 8-month supply of a basic prenatal with folic acid.) What’s so special about 5-MTHF? “We formulate our multivitamins with 5-MTHF because it’s a biologically active form,” says Ritual’s website. Nice try. Folic acid is also “biologically active.”

The website also says that Ritual has done a “human clinical trial” to back up its claims. But the company didn’t respond to our questions about the trial, and we could find no published version of it.

Our advice: If you have an MTHFR gene variant, rest easy. An ordinary multivitamin with folic acid or a dedicated folic acid supplement can prevent neural tube defects in your baby. There’s no reason to spend more money on a prenatal vitamin with 5-MTHF.

Folic acid supplementation does not cause infertility, autism, or postpartum depression 

Influencers who are trying to sell alternatives to folic acid or tests for the MTHFR variant sometimes say that folic acid causes infertility, autism in children, or depression during or after pregnancy. Some go so far as to claim that you can avoid classic symptoms of pregnancy like mood swings, nausea, and fatigue by buying the folate-based multivitamin they’re promoting. But there’s no solid evidence that any of that is true.

In 2017, the United States Preventive Services Task Force, an independent panel of experts in disease prevention and evidence-based medicine, found no evidence of serious harm after it reviewed the published research on folic acid during pregnancy. According to the review, no studies have found evidence that folic acid supplements cause autism in children or cancer in the birthing parent. In fact, a 2022 review links taking folic acid supplements during pregnancy to 43 percent lower odds that a child develops autism. And another review, of eight studies published in the same year, found that taking folic acid is linked with a 26 percent lowerodds of depression during and after pregnancy.

Despite that evidence, some influencers continue to make irresponsible claims about taking folic acid during pregnancy. That kind of fearmongering may steer some pregnant people away from getting the safe folic acid that is essential for their baby’s health.  

Bottom line

Ignore the hype. Don’t worry about MTHFR gene variants. And don’t be swayed by companies or influencers pushing folate supplements. Folic acid is safe, and it’s the only form of folate that has been shown to prevent neural tube birth defects.