Getting the Right Amount of Folic Acid


Folic acid is the synthetic form of folate, a type of vitamin B. Because the lack of this vitamin can cause serious birth defects, such as spina bifida, in the United States it is often added to grains used in foods, which are labeled “vitamin-fortified.”  Folic acid is also included in many multi-vitamins. As with all vitamins, it’s important to get the right amount.  Too much can be just as dangerous as too little.  Here’s what you need to know.

How to Make Sure You Have Enough Folic Acid

Vitamin Pills:  Folic acid is easier to absorb in your diet than natural folate is. Most daily multivitamin pills contain the recommended dietary allowance (RDA) of 400 micrograms (mcg) of folic acid.

Foods:  Leafy greens like spinach, many other vegetables and fruits are high in folate, such as citrus fruits, broccoli, bananas, peas, and beans.[1] However folate in food is unstable; storing fruits and veggies at room temperature or cooking can destroy folate because it is sensitive to light and heat.[2]

In the United States grain products marked as “enriched,” such as cereal, flour, pasta, rice, and white bread are fortified with folic acid. In fact, fortified white bread contains twice as much folic acid as whole grain or whole wheat bread. Cereals known for their nutritional benefits, such as Total, Product 19, Cheerios Plus, Special K Plus, Life, and Smart Start are fortified to contain 400 mcg of folic acid.[3] Sugary cereals and many popular adult cereals also contain folic acid, but usually only up to 100-200 mcg per serving. Breakfast bars contain much less, so to reach 400 mcg, a person may need to consume 1,000 calories or more of these “convenience breakfasts.” People who are on low-carb diets and who aren’t eating fortified grains may need to take vitamins with folic acid.

How Folic Acid Prevents Birth Defects

To prevent birth defects, women need to have the right amount of folic acid in their bodies before they get pregnant. It is not enough to take folic acid after you find out you are pregnant; to prevent birth defects, you need to have enough at the moment you conceive and especially during the first month, as well as throughout the pregnancy. The type of birth defects that are proven to be linked to low levels of folic acid are called neural tube defects. Women who are diabetic, epileptic, or obese also have an increased risk of a having a baby with a neural tube defect.[4]

Neural tube defects occur when the neural tube, which later develops into the brain and spine, does not form correctly. About 2,500 babies in the U.S. are born with these defects each year, including spina bifida. Spina bifida is a relatively common neural tube defect, where the two sides of the spinal cord don’t join together properly. The spinal cord and the bony part covering it are supposed to fuse together at the end of the first month of pregnancy. If that doesn’t happen, the backbones and spinal cord do not develop properly and a sac of spinal fluid may protrude from the baby’s back. Spina bifida is not usually fatal, but can cause lifelong debilitating pain and difficulty walking.[4] Another type of neural tube defect is anencephaly, which is when the brain and skull bones do not form and leave the fetus’s brain unprotected. Sometimes called “water on the brain,” this can cause a miscarriage or the infant may die shortly after birth.[3] The neural tube forms in the first 28 days after conception so if a woman waits until she’s sure she’s pregnant before taking folic acid, she will have missed her chance to prevent many birth defects, including spina bifida.[4]

Studies show that if all women in the United States consumed enough folic acid throughout their pregnancies, birth defects could be reduced by up to 70 percent. Unfortunately, most American women only consume about half of the recommended dietary allowance of folic acid.[4] Obviously, this is most likely among women who avoid carbs and don’t take vitamins. Since so many pregnancies are unplanned, health experts recommend that all women of childbearing age take 400 mcg of folic acid a day. When they are pregnant they should take 600 mcg a day and 500 mcg a day while breastfeeding. Interestingly, low folate levels in fathers-to-be may also be linked to birth defects. A study of rats published in 2013 found that when fathers didn’t have enough folic acid in their diets, their offspring were more likely to have birth defects.[5]

You can increase your folic acid by eating right and taking a supplement but did you know that some of the things you might enjoy can decrease your folic acid? Drinking alcoholic beverages and sunbathing both reduce your folic acid levels. Alcohol interferes with your body’s ability to use the folic acid available to it, so women who drink an average of more than one alcoholic drink a day are especially likely to need more folic acid. A study published in January 2014 found that the more UV light women were exposed to by sunbathing or using tanning beds, the more their blood folate levels dropped. UV light even reduced the effectiveness of the folic acid supplements the women were taking.[6] If you are considering getting pregnant, there’s something else you should know about folic acid:  women who take it for at least a year before becoming pregnant are half as likely to give birth prematurely. Babies born too early are at higher risk for many health problems.[7]

What about Women Who are Not of Childbearing Age?

Women who are not of childbearing age may want to concentrate on eating a balanced and varied diet rather than take a supplement. If they lack a healthy diet or drink alcohol most days, they should probably take a folic acid supplement. They should pick one that doesn’t have more folic acid than the RDA of 400 mcg, especially if they eat a lot of fortified foods already supplemented with folic acid, such as enriched breads, cereals and pastas. When in doubt, this information will be listed on the nutrition label. Folic acid supplements can improve memory and thinking among older people but only when they have very low levels of folic acid to begin with. A 3-year study in the Netherlands found that those who took high doses of folic acid showed improvements in memory skills and ability to process information compared with the study participants who took a placebo.[8]

However, this study might not be relevant to people in the U.S. since food in the U.S. is fortified with folic acid and therefore few adults have dangerously low levels. Until recently, many researchers had hoped that taking folic acid might help delay Alzheimer’s disease. Unfortunately, research has shown no benefit for Alzheimer’s patients who took high doses of folic acid.[9] Studies have also suggested that folic acid supplements may reduce the chances of experiencing a stroke or heart disease in healthy adults.[10,11]


Taking too much folic acid may add some risks to your health:

  • Consuming more than 1000 mcg of folic acid daily, more than double the recommended amount, can hide a vitamin B-12 deficiency.  Lack of vitamin B-12 can cause irreversible nerve damage over time.[4]
  • Some recent studies show that too much folate from folic acid supplements can increase the risk to breast cancer among postmenopausal women.[12,13] A 2013 animal study suggested that too much folate could speed breast cancer progression.[14]

Bottom Line

Making sure pregnant women get the appropriate amount of folic acid or folates is an easy way to protect their unborn child’s health. Since the first month of pregnancy is most important, starting from the day of conception, the best way to avoid spina bifida and other neural tube defects is to make sure that all women of reproductive age (even those not planning to get pregnant) consume 400 mcgs of folic acid every day. Men and older women also benefit from folic acid.  Most people consume too little folic acid rather than too much, but getting too much can also be harmful.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

  1. March of Dimes. Pregnancy and Newborn Health Education Center: Folic Acid. February 2010.
  2. Crider KS, Bailey LB, Berry RJ. Folic acid food fortification—its history, effect, concerns, and future directions. Nutrients. 2011;3(3):370-384.
  3. Centers for Disease Control. Folic Acid Frequently Asked Questions. January 30, 2008.
  4. March of Dimes. Preconception Risk Reduction: Folic Acid. February 2010.
  5. Lambrot R, Xu C, Saint-Phar S, Chountalos G, Cohen T, Paquet M, Suderman M, Hallett M, Kimmins S. Low paternal dietary folate alters the mouse sperm epigenome and is associated with negative pregnancy outcomes. Nature communications. 2013;4.
  6. Jablonski NG. A possible link between neural tube defects and ultraviolet light exposure. Medical Hypotheses. 1999;52(6):581–582.
  7. Bukowski R, Malone FD, Porter FT, Nyberg DA, Comstock CH, Hankins GDV, Eddleman K et al. Preconceptional folate supplementation and the risk of spontaneous preterm birth: a cohort study. PLoS Medicine. 2009;6:e1000061.
  8. Durga, J. et al. Effect of 3-year folic acid supplementation on cognitive function in older adults in the FACIT trial: a randomized, double blind, controlled trial. The Lancet. 2007;369:208-216.
  9. Aisen, P. et al. High-Dose B Vitamin Supplementation and Cognitive Decline in Alzheimer Disease. The Journal of the American Medical Association. 2008;300(15):1774-1783.
  10. Bazzano LA, He J, Ogden LG, Loria C, Vupputuri S, Myers L, Whelton PK. Dietary intake of folate and risk of stroke in US men and women NHANES I epidemiologic follow-up study. Stroke. 2002; 33(5):1183-1189.
  11. Guelpen B, Hultdin J, Johansson I, Stegmayr B, Hallmans G, Nilsson TK, Weinehall L, Witthöft C, Palmqvist R, Winkvist A. Folate, Vitamin B12, and Risk of Ischemic and Hemorrhagic Stroke A Prospective, Nested Case-Referent Study of Plasma Concentrations and Dietary Intake. Stroke. 2005;36(7):1426-1431.
  12. Stevens VL, McCullough ML, Sun J, Gapstur SM. Folate and other one-carbon metabolism-related nutrients and risk of postmenopausal breast cancer in the Cancer Prevention Study II Nutrition Cohort. Am J Clin Nutr. 2010;91:1708–1715.
  13. Stolzenberg-Solomon RZ, Chang S, Leitzmann MF, Johnson KA, Johnson C, Buys SS, Hoover RN, Ziegler RG. Folate intake, alcohol use, and postmenopausal breast cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The American journal of clinical nutrition. 2006;83(4):895-904.
  14. Manshadi SD, Ishiguro L, Sohn KJ, Medline A, Renlund R, Croxford R, Kim YI. Folic Acid Supplementation Promotes Mammary Tumor Progression in a Rat Model. PLOS ONE. 2014; 9(1):e84635.