Is 1600 mcg of folic acid too much when pregnant

Mothers that take excessive amounts of folic acid during pregnancy may predispose their daughters to diabetes and obesity later in life, according to a new study published today in the Journal of Endocrinology. With high dose supplements being widely available, the study calls for a need to establish a safe upper limit of folic acid intake for pregnant women.

A Portuguese research team from the Faculty of Medicine of the University of Porto and the Catholic University of Portugal gave rats 20 times their recommended daily amount of folic acid throughout mating, the pregnancy period and lactation.

These rats gave birth to babies who grew up to be overweight and insulin resistant in adulthood. The babies also grew up to be deficient in adiponectin – a hormone that protects them against diabetes and obesity - and had irregular feeding behaviour. All of these symptoms were more pronounced in female adults. On the other hand, rats consuming the recommended daily amount of folic acid had babies who grew up to be healthier adults.

An adequate intake of folic acid is essential to reduce the risk of babies suffering from neural tube defects such as spina bifida, particularly during the first 10 weeks of pregnancy. The World Health Organisation recommends that healthy pregnant women take 0.4 mg of folic acid per day. Women with a family history of neural tube defects are recommended to take ten times this amount, for which 5 mg folic acid pills are widely available.

However, few studies have looked at the safe upper limit of folic acid intake, even though pregnant women around the world are consuming increasingly high amounts of folic acid thanks to food fortification policies and widely available supplements and multivitamins.

“While taking a minimum of 0.4mg of folic acid per day is essential when pregnant, our study shows that it is possible to have too much of a good thing”, said lead author of the study Professor Elisa Keating. “Considering the increasing amount of folic acid consumed during pregnancy through fortified foods, multivitamin pills and supplements, the search for a safe upper dose of folic acid is urgently needed”.

“Our study clarifies the potential effects of excess folic acid exposure and may play an important role on rethinking current public health policies surrounding folic acid supplementation”.

The researchers will continue to investigate the mechanisms by which folic acid affects the metabolism of rat offspring and how their findings can be applied to human health recommendations.

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Materials provided by Society for Endocrinology. Note: Content may be edited for style and length.

Journal Reference:

E. Keating, A. Correia-Branco, J. R. Araujo, M. Meireles, R. Fernandes, L. Guardao, J. T. Guimaraes, F. Martel, C. Calhau. Excess perigestational folic acid exposure induces metabolic dysfunction in post-natal life. Journal of Endocrinology, 2015; 224 (3): 245 DOI: 10.1530/JOE-14-0448

Prenatal vitamins can have too much folic acid, many do, and there is potential risk associated with this.

Folic acid is a synthetic form of the B vitamin folate (B9) which naturally occurs in foods, such as green leafy vegetables. Folate can help reduce the risk of your baby being born with spina bifida (a leading cause of childhood paralysis) and other birth defects. While most adults need 400 mcg DFE (Dietary Folate Equivalents) of folate daily, pregnant women need 600 mcg DFE. To be sure you get this, it's suggested that you take a supplement with 400 mcg DFE of folic acid and that you get the rest of your folate from your diet — from foods such as dark green leafy vegetables, oranges, and grain products enriched with folic acid.

Unfortunately, many prenatal supplements provide 800 mcg or more of folic acid — double the recommended amount from a supplement. That's not all. Folic acid is absorbed much better (about 70% better) than folate from foods. This means that a prenatal supplement with 800 mcg of folic acid gives you the equivalent of 1,360 mcg DFE of folate. On top of this, many manufacturers put in extra folic acid (30% or more is not uncommon), so it's quite possible that your supplement which lists 800 mcg of folate from folic acid is giving you the equivalent of about 1,800 mcg of folate.

The Tolerable Upper Intake Level (UL) for folate is 1,000 mcg, which only applies to synthetic forms, such as folic acid and methylfolate, found in supplements in fortified foods. It does not apply to folate found naturally in foods. Note that the UL is based on mcg and not mcg DFEs. Consequently, a product that contains 800 mcg of folic acid will not exceed the adult UL of 1,000 mcg folate, even though, nutritionally it provides about 1,336 mcg DFE. It's best not to exceed this because prolonged intake of excessive folic acid can cause kidney damage and can complicate the diagnosis of vitamin B-12 deficiency (folic acid supplementation can mask a symptom of vitamin B-12 deficiency). Of particular concern to pregnant women is that excessively high blood levels of folate (>59 nmol/L) in their blood was found to be associated with an approximate twofold increased risk of autism in their children according to an observational study in Baltimore in which 10% of women exceeded this level (Raghavan, International Meeting for Autism Research 2016). The study also found that when blood levels of both folate and vitamin B-12 were excessively high, the risk of autism was 17.6 times greater. (Note: Getting adequate folate during pregnancy may reduce the risk of autism; the concern is with getting too much).

In addition, one study found that taking 800 mcg or more of folic acid from supplements during the month before pregnancy through mid- pregnancy was associated with a 32% increased risk of gestational hypertension (high blood pressure in women during pregnancy).

So what should you do?

ConsumerLab.com has tested and compared many prenatal supplements and other multivitamins. Unfortunately, some have too much folic acid. For now it may be safest to skip a "prenatal" vitamin with 800 mcg of folic acid and, instead, choose a daily multivitamin which provides 400 mcg of folic acid. The multi should also provide other nutrients of particular importance during pregnancy such as iodine (220 mcg), vitamin D (600 IU), and calcium (1,000 mg per day is the daily requirement, but don't take more than 500 mg at a time from a supplement). A challenge, however, is getting adequate iron, since the daily requirement during pregnancy (27 mg) is higher than for other pre-menopausal women (18 mg). A women's multi can provide all the nutrients listed above, but typically just 18 mg of iron, so you'll need to get extra iron from your diet. Alternatively, you can choose another multi and take a separate iron supplement providing about 27 mg of iron.

Your Prenatal Vitamin Needs a Check-up with CL founder, Dr. Tod Cooperman

Folic acid is the man-made form of folate, a B vitamin. Folate is found naturally in certain fruits, vegetables, and nuts. Folic acid is found in vitamins and fortified foods.

Folic acid and folate help the body make healthy new red blood cells. Red blood cells carry oxygen to all the parts of your body. If your body does not make enough red blood cells, you can develop anemia. Anemia happens when your blood cannot carry enough oxygen to your body, which makes you pale, tired, or weak. Also, if you do not get enough folic acid, you could develop a type of anemia called folate-deficiency anemia.

Everyone needs folic acid to be healthy. But it is especially important for women:

Before and during pregnancy. Folic acid protects unborn children against serious birth defects called neural tube defects. These birth defects happen in the first few weeks of pregnancy, often before a woman knows she is pregnant. Folic acid might also help prevent other types of birth defects and early pregnancy loss (miscarriage). Since about half of all pregnancies in the United States are unplanned1, experts recommend all women get enough folic acid even if you are not trying to get pregnant.
To keep the blood healthy by helping red blood cells form and grow. Not getting enough folic acid can lead to a type of anemia called folate-deficiency anemia. Folate-deficiency anemia is more common in women of childbearing age than in men.

You can get folic acid in two ways.

Through the foods you eat. Folate is found naturally in some foods, including spinach, nuts, and beans. Folic acid is found in fortified foods (called "enriched foods"), such as breads, pastas, and cereals. Look for the term "enriched" on the ingredients list to find out whether the food has added folic acid.
As a vitamin. Most multivitamins sold in the United States contain 400 micrograms, or 100% of the daily value, of folic acid. Check the label to make sure.

All women need 400 micrograms of folic acid every day. Women who can get pregnant should get 400 to 800 micrograms of folic acid from a vitamin or from food that has added folic acid, such as breakfast cereal.2 This is in addition to the folate you get naturally from food.

Some women may need more folic acid each day. See the chart to find out how much folic acid you need.

If you:	Amount of folic acid you may need daily2
Could get pregnant or are pregnant	400–800 micrograms.2 Your doctor may prescribe a prenatal vitamin with more.
Had a baby with a neural tube defect (such as spina bifida(SPEYE-nuh BIF-ih-duh)) and want to get pregnant again	4,000 micrograms. Your doctor may prescribe this amount. Research shows taking this amount may lower the risk of having another baby with spina bifida.3
Have a family member with spina bifida and could get pregnant	4,000 micrograms. Your doctor may prescribe this amount.
Have spina bifida and want to get pregnant	4,000 micrograms. Your doctor may prescribe this amount. Women with spina bifida have a higher risk of having children with the condition.
Take medicines to treat epilepsy, type 2 diabetes, rheumatoid arthritis, or lupus	Talk to your doctor or nurse. Folic acid supplements can interact with these medicines.
Are on dialysis for kidney disease	Talk to your doctor or nurse.
Have a health condition, such as inflammatory bowel disease or celiac disease, that affects how your body absorbs folic acid	Talk to your doctor or nurse.

Yes, certain groups of women do not get enough folic acid each day.4

Women who can get pregnant need more folic acid (400 to 800 micrograms).2
Nearly one in three African-American women does not get enough folic acid each day.
Spanish-speaking Mexican-American women often do not get enough folic acid. However, Mexican-Americans who speak English usually get enough folic acid.5

Not getting enough folic acid can cause health problems, including folate-deficiency anemia, and problems during pregnancy for you and your unborn baby.

If you do not get enough folic acid before and during pregnancy, your baby is at higher risk for neural tube defects.

Neural tube defects are serious birth defects that affect the spine, spinal cord, or brain and may cause death. These include:

Spina bifida.6 This condition happens when an unborn baby's spinal column does not fully close during development in the womb, leaving the spinal cord exposed. As a result, the nerves that control the legs and other organs do not work. Children with spina bifida often have lifelong disabilities. They may also need many surgeries.
Anencephaly(an-en-SEF-uh-lee).7 This means that most or all of the brain and skull does not develop in the womb. Almost all babies with this condition die before or soon after birth.

Yes. All women who can get pregnant need to take 400 to 800 micrograms of folic acid every day, even if you're not planning to get pregnant.2 There are several reasons why:

Your birth control may not work or you may not use birth control correctly every time you have sex. In a survey by the Centers for Disease Control and Prevention, almost 40% of women with unplanned pregnancies were using birth control.8
Birth defects of the brain and spine can happen in the first few weeks of pregnancy, often before you know you are pregnant. By the time you find out you are pregnant, it might be too late to prevent the birth defects.
You need to take folic acid every day because it is a water soluble B-vitamin. Water soluble means that it does not stay in the body for a long time. Your body metabolizes (uses) folic acid quickly, so your body needs folic acid each day to work properly.

Folate is found naturally in some foods. Foods that are naturally high in folate include:

Spinach and other dark green, leafy vegetables
Oranges and orange juice
Nuts
Beans
Poultry (chicken, turkey, etc.) and meat
Whole grains

Folic acid is added to foods that are refined or processed (not whole grain):

Breakfast cereals (Some have 100% of the recommended daily value — or 400 micrograms — of folic acid in each serving.)
Breads and pasta
Flours
Cornmeal
White rice

Since 1998, the Food and Drug Administration (FDA) has required food manufacturers to add folic acid to processed breads, cereals, flours, cornmeal, pastas, rice, and other grains.9 For other foods, check the Nutrition Facts label on the package to see if it has folic acid. The label will also tell you how much folic acid is in each serving. Sometimes, the label will say "folate" instead of folic acid.

You can get enough folic acid from food alone. Many breakfast cereals have 100% of your recommended daily value (400 micrograms) of folic acid.

If you are at risk for not getting enough folic acid, your doctor or nurse may recommend that you take a vitamin with folic acid every day. Most U.S. multivitamins have at least 400 micrograms of folic acid. Check the label on the bottle to be sure. You can also take a pill that contains only folic acid.

If swallowing pills is hard for you, try a chewable or liquid product with folic acid.

Look for "USP" or "NSF" on the label when choosing vitamins. These "seals of approval" mean the pills are made properly and have the amounts of vitamins it says on the label. Also, make sure the pills have not expired. If the bottle has no expiration date, do not buy it.

Ask your pharmacist for help with selecting a vitamin or folic acid-only pill. If you are pregnant and already take a daily prenatal vitamin, you probably get all the folic acid you need. Check the label to be sure.

Vitamin label

Check the "Supplement Facts" label to be sure you are getting 400 to 800 micrograms (mcg) of folic acid.2

Yes, many people get enough folic acid from food alone. Some foods have high amounts of folic acid. For example, many breakfast cereals have 100% of the recommended daily value (400 micrograms) of folic acid in each serving. Check the label to be sure.

Some women, especially women who could get pregnant, may not get enough folic acid from food. African-American women and Mexican Americans are also at higher risk for not getting enough folic acid each day. Talk to your doctor or nurse about whether you should take a vitamin to get the 400 micrograms of folic acid you need each day.

Folate-deficiency anemia is a type of anemia that happens when you do not get enough folate. Folate-deficiency anemia is most common during pregnancy. Other causes of folate-deficiency anemia include alcoholism and certain medicines to treat seizures, anxiety, or arthritis.

The symptoms of folate-deficiency anemia include:

Fatigue
Headache
Pale skin
Sore mouth and tongue

If you have folate-deficiency anemia, your doctor may recommend taking folic acid vitamins and eating more foods with folate.

Yes, you can get too much folic acid, but only from man-made products such as multivitamins and fortified foods, such as breakfast cereals. You can't get too much from foods that naturally contain folate.

You should not get more than 1,000 micrograms of folic acid a day, unless your doctor prescribes a higher amount. Too much folic acid can hide signs that you lack vitamin B12, which can cause nerve damage.10

Yes. Women who have gone through menopause still need 400 micrograms of folic acid every day for good health. Talk to your doctor or nurse about how much folic acid you need.

Yes. Under the Affordable Care Act (the health care law), all Health Insurance Marketplace plans and most other insurance plans cover folic acid pills for women who could get pregnant at no cost to you. Check with your insurance provider to find out what's included in your plan.

For information about other services covered by the Affordable Care Act, visit HealthCare.gov.

Finer, L.B., Zolna, M.R. (2016). Declines in unintended pregnancy in the United States, 2008-2011. The New England Journal of Medicine; 374(9):843–52.
U.S. Preventive Services Task Force. (2016). Final Recommendation Statement: Folic Acid for the Prevention of Neural Tube Defects: Preventive Medication.
CDC. (2016). Folic Acid Recommendations.
Bailey, R.L., Dodd, K.W., Gahche, J.J., Dwyer, J.T., McDowell, M.A., Yetley, E.A., et al. (2010). Total folate and folic acid intake from foods and dietary supplements in the United States: 2003–2006. American Journal of Clinical Nutrition; 91(1): 231–237.
Hamner, H.C., Cogswell, M.E., Johnson, M.A. (2011). Acculturation factors are associated with folate intakes among Mexican American women. The Journal of Nutrition; 141(10): 1889–97.
CDC. (2016). Spina Bifida.
CDC. (2015). Facts about Anencephaly.
Mosher, W.D., Jones, J., Abma, J.C. (2012). Intended and Unintended Births in the United States: 1982–2010 (PDF, 404 KB). National Health Statistics Reports; no. 55.
U.S. Government Printing Office. (1996). Food Standards: Amendment of Standards of Identity For Enriched Grain Products to Require Addition of Folic Acid (PDF, 215 KB). Federal Register; 61(44): 8781.
Morris, M.S., Jacques, P.F., Rosenberg, I.H., et al. (2007). Folate and vitamin B12 status in relation to anemia, macrocytosis and cognitive impairment in older Americans in the age of folic acid fortification. Am J Clin Nutr; 85(1):193–200.

The Office on Women's Health is grateful for the medical review by:

Sarah R. Linde, M.D., RADM, U.S. Public Health Service, Chief Public Health Officer and Acting Deputy Associate Administrator Healthcare Systems Bureau, Health Resources and Services Administration
Iris R. Mabry-Hernandez, M.D., M.P.H., Medical Officer, U.S. Preventive Services Task Force Program, Center for Evidence and Practice Improvement, Agency for Healthcare Research and Quality, Department of Health and Human Services

All material contained on these pages are free of copyright restrictions and maybe copied, reproduced, or duplicated without permission of the Office on Women’s Health in the U.S. Department of Health and Human Services. Citation of the source is appreciated.

Page last updated: February 12, 2021