Folic acid is the man-made form of folate, a B vitamin (B9) your body needs to make new cells. Its best-proven use is preventing serious birth defects of the brain and spine when taken before and during early pregnancy.

The short answer

  • What it is: The form of vitamin B9 used in vitamins and added to enriched grains like bread, cereal, pasta, and rice.
  • What it does: Helps your body make DNA and new cells, including red blood cells.
  • Why women hear about it most: Getting 400 micrograms (mcg) a day before and during early pregnancy lowers the risk of neural tube defects such as spina bifida. The CDC recommends it for anyone who could become pregnant.
  • Everyone needs folate: Adults need 400 mcg DFE a day from food and vitamins combined. Kids need less, and pregnant and breastfeeding women need more.

Folate vs. folic acid

The two words are often used as if they mean the same thing, but they don’t quite.

  • Folate is the umbrella term for every form of vitamin B9. It includes the folate found naturally in foods like leafy greens and beans.
  • Folic acid is one specific, man-made form. It’s the form used in most vitamins and in fortified foods. It’s also the only form of folate shown in studies to help prevent neural tube defects, according to the CDC.
  • Methylfolate (5-MTHF) is another form sold in some supplements. It hasn’t been tested in clinical trials for preventing neural tube defects, so the folic acid recommendations for pregnancy don’t apply to it, according to the NIH.

One practical difference: your body absorbs folic acid better. It takes in at least 85% of the folic acid in a vitamin or fortified food eaten with a meal, compared with about 50% of the folate naturally in food, according to the NIH. For a deeper comparison, see our article Folic Acid or Folate? [internal link]

What folate does in your body

Every new cell your body makes depends on folate. It’s needed to make DNA and RNA, the instructions inside each cell, and for cells to divide properly, according to the NIH.

That matters most where cells are made quickly:

  • Red blood cells. Without enough folate, your body makes red blood cells that are too large and don’t work well. This is called folate-deficiency anemia, and it can cause tiredness, weakness, trouble concentrating, headaches, a racing heart, and shortness of breath.
  • Early pregnancy. In the first weeks, a baby’s brain and spinal cord form from a structure called the neural tube, which closes 21 to 28 days after conception. Enough folate during that window lowers the risk that it won’t close properly.
  • Skin, hair, and nails. These are made of new cells too. Folate deficiency can change the color of skin, hair, and fingernails, and cause sores on the tongue and in the mouth.

True folate deficiency is uncommon in the U.S., partly because grain products are fortified. It’s more likely with heavy drinking, digestive conditions like celiac disease, some medicines, and the higher needs of pregnancy.

How much your family needs

Needs rise with age, then jump during pregnancy and breastfeeding. The daily amounts below come from the NIH and count folate from all sources, food and vitamins together.

Age or stage Daily need (mcg DFE) Upper limit for folic acid from vitamins and fortified foods (mcg)
Birth to 6 months 65 Not set; breast milk, formula, and food only
7 to 12 months 80 Not set; breast milk, formula, and food only
1 to 3 years 150 300
4 to 8 years 200 400
9 to 13 years 300 600
14 to 18 years 400 800
Adults 19 and older 400 1,000
Pregnant 600 800 (ages 14–18); 1,000 (19 and older)
Breastfeeding 500 800 (ages 14–18); 1,000 (19 and older)

What DFE means. DFE (dietary folate equivalents) adjusts for how much better your body absorbs folic acid than food folate. A vitamin with 400 mcg of folic acid will usually show about 680 mcg DFE on its label.

The extra recommendation for women. On top of a varied diet, anyone who could become pregnant should get 400 mcg of folic acid a day from a vitamin, fortified foods, or both, according to the CDC.

A note for parents. Most children get enough folate from a normal diet that includes fortified grains. Many children who take vitamins actually go over the upper limit for their age: 30% to 66% of kids ages 1 to 13 who take folic acid supplements do, according to the NIH. Check the label on your child’s vitamin, and ask their doctor if you’re unsure.

What’s proven and what isn’t

Folic acid gets credit online for a long list of benefits. Only two are firmly established; the rest range from “possible” to “not supported.” This summary draws mainly on the NIH’s reviews of the research (folate, pregnancy).

Claim Where it stands What the research shows
Prevents neural tube defects Proven Clinical trials and 25+ years of U.S. fortification data. Recommended by the CDC and U.S. Preventive Services Task Force.
Prevents and treats folate-deficiency anemia Proven Folate is needed to make healthy red blood cells. Anemia caused by low folate usually improves with treatment within 3 to 6 months (MedlinePlus).
Lowers stroke risk Possible Several reviews found a lower stroke risk, mainly in people who started with low folate, such as in countries without fortified foods.
Prevents other birth defects (heart defects, cleft lip) Possible Some studies suggest a benefit, but a review of trials found the data too limited to say for sure.
Lowers risk of gestational diabetes Possible A large NIH study found women who took folic acid before pregnancy were 22% less likely to develop it. It was observational, so it shows a link, not proof.
Lowers autism risk in children Unclear Some observational studies found a lower risk; others didn’t. The NIH says it’s unclear.
Improves mood or treats depression Mixed Low folate is linked to depression in some studies. Results as an add-on to antidepressants are mixed, and many doses studied exceed the upper limit.
Protects memory or prevents dementia Mostly not shown Most trials found no benefit, though some found one in people with high homocysteine or low B-vitamin levels.
Prevents heart attacks or heart disease Not shown Supplements lower homocysteine but haven’t lowered heart attack or heart disease risk in trials.
Prevents cancer Not shown No reduction in people who already get enough folate. Some studies link high-dose supplements to higher prostate cancer risk.
Boosts male fertility Not shown A trial of 2,370 couples found high-dose folic acid plus zinc didn’t improve sperm or pregnancy rates (NIH).
Improves hair, skin, or acne Not well studied Deficiency can affect skin and hair color, but there’s little research on extra folic acid for people who already get enough.

Where to get it

There are three sources: food, fortified foods, and vitamins. Most people get enough folate from the first two. Women who could become pregnant usually need the third as well to reliably reach 400 mcg of folic acid.

  • Food. Dark leafy greens, beans and peas, asparagus, Brussels sprouts, avocado, and oranges are good natural sources. A half-cup of boiled spinach has about 131 mcg; a half-cup of black-eyed peas has about 105 mcg (NIH). Our guide to foods high in folate lists more [internal link].
  • Fortified foods. Since 1998, the U.S. has required folic acid in enriched breads, cereals, flour, pasta, and rice. Since 2016, corn masa flour, used for tortillas and tamales, can be fortified too. Look for “folic acid” on the label.
  • Vitamins. Most multivitamins and nearly all prenatal vitamins contain folic acid or another form of folate.

Food alone often isn’t enough before pregnancy. About half of U.S. women say enriched grains are their only source of folic acid, according to the CDC, and food folate is absorbed less well than folic acid.

Safety

Folic acid is safe at the usual doses. A few limits and cautions are worth knowing.

Upper limit. For adults, the upper limit for folic acid from vitamins and fortified foods is 1,000 mcg a day (see the table above for kids and teens). There’s no limit on folate from regular food, according to the NIH. Higher doses should be taken only when a doctor recommends them, as with the 4,000 mcg dose for women who’ve had a pregnancy affected by a neural tube defect.

Vitamin B12. Large amounts of folic acid can correct the anemia caused by low vitamin B12 without fixing the nerve damage B12 deficiency causes, which can delay a diagnosis. If you have symptoms like numbness or tingling, or you eat little or no animal food, ask about B12 before taking extra folic acid.

Medicines. Folic acid can interact with methotrexate (used for some cancers and autoimmune conditions), some anti-seizure medicines such as phenytoin, carbamazepine, and valproate, and sulfasalazine (used for ulcerative colitis). Some of these lower folate levels, and folic acid can lower the levels of some anti-seizure medicines. If you take any of them, talk with your doctor before starting, stopping, or changing a folic acid supplement.

Doubling up. Check all your labels. A prenatal vitamin plus a separate folic acid pill plus a highly fortified cereal can add up quickly.

Sources

This article is for general information and is not a substitute for advice from your health care provider.