Why you need folic acid

If you're pregnant or might become pregnant, you need folic acid (vitamin B9) for a number of compelling reasons.

Folic acid helps prevent neural tube defects (NTDs)—serious birth defects of the spinal cord (such as spina bifida) and the brain (such as anencephaly). Neural tube defects occur at a very early stage of development, before many women even know they're pregnant. They affect about 3,000 pregnancies a year in the United States.

How much folic acid you need

To reduce your baby's risk of developing a neural tube defect, experts recommend that you take 400 micrograms (mcg) of folic acid per day, beginning at least a month before you start trying to get pregnant.

In fact, because half of the pregnancies in the United States are unplanned, the CDC, the U.S. Public Health Service, the March of Dimes, the American College of Obstetricians and Gynecologists (ACOG), and other experts strongly recommend that all women of childbearing age get 400 mcg of folic acid every day.

Some groups, such as the U.S. National Institutes of Health, suggest boosting your intake to at least 600 mcg daily once you're pregnant.

The neural tube—from which your baby's spine and brain develop – begins to form about three weeks after conception, so it's critical to get a sufficient daily dose of folic acid before conception and during the first trimester of pregnancy.

Check the label of your multivitamin supplement to be sure you're getting enough. If you're not, you can switch brands or take folic acid separately. (Never double up on your multivitamins.)

If you're taking prescription prenatal vitamins, they probably contain 800 to 1,000 mcg of folic acid. Again, check the label.

Don't take more than 1,000 mcg per day of folic acid unless your healthcare provider advises you to. This is particularly important if you are a vegan. Vegans are at risk of being deficient in vitamin B12 and taking too much folic acid would make it hard to diagnose that deficiency.

When you might need extra folic acid

Women who are obese appear to be more likely to have a baby with a neural tube defect, although the reason for this is still unclear. If you're significantly overweight, see your healthcare provider before you try to conceive. She may advise you to take more than 400 mcg of folic acid a day.

If you've previously been pregnant with a baby with a neural tube defect, be sure your current providers are aware of this and schedule a visit before you try to get pregnant. With no intervention, women in this situation have a 2 to 5 percent chance of having another pregnancy complicated by an NTD.

The good news is that this risk can be reduced significantly by taking a very large dose of folic acid. Talk to your doctor about how much folic acid you should take if you're in this situation.

Women who are diabetic or are taking certain antiseizure medications are also more likely to have a baby with an NTD. If either of these situations applies to you, see your provider at least a month before trying to conceive to find out how much folic acid you should be taking and to monitor your condition in general.

Food sources of folic acid

Oddly enough, research shows that the body absorbs the synthetic version of this vitamin (folic acid) much better than the version that occurs naturally in certain foods (folate). While enriched cereals and other grain products are fortified with the synthetic version, most women don't eat these foods consistently enough to rely on them as a source of folic acid.

Foods that are rich in naturally occurring folate include lentils; dried beans and peas; dark green vegetables such as broccoli, spinach, collard or turnip greens, okra, and asparagus; and citrus fruit and juice.

These foods aren't a substitute for supplemental folic acid. Instead, consider them a complement to your supplement. Because while your body absorbs all of the folic acid in a supplement, it absorbs only some of the naturally occurring folate from the food you eat. What's more, folate can be lost during storage or destroyed by cooking.

Food manufacturers are required by the U.S. Food and Drug Administration to add folic acid to enriched grain products, such as breakfast cereals, bread, pasta, and rice, so that each serving contains at least 20 percent of the daily requirement. Some fortified breakfast cereals contain 100 percent.

That said, unless you go out of your way to eat a complete serving of a fully fortified cereal—that is, one that contains 100 percent of the Daily Value of folic acid—every day, you probably won't get enough synthetic folic acid from food.

Is a supplement recommended?

Yes. Many authorities, including ACOG and the March of Dimes, recommend that all women of childbearing age take a multivitamin with folic acid or a folic acid supplement every single day.

The signs of a folic acid deficiency

The signs of folic acid deficiency can be subtle. You may have diarrhea, loss of appetite, and weight loss, as well as weakness, a sore tongue, headaches, heart palpitations, and irritability.

If you're only mildly deficient, you may not notice any symptoms at all, but you won't be getting the optimal amount for your baby's early embryonic development.