Jessica Levasseur and Brandel France de Bravo, MPH September 2010
Folic acid, a type of Vitamin B, is added to grains that we eat in the United States and is also in many multi-vitamins. It’s so important we want to make sure you know about it.
Folic acid helps make healthy, new cells.1 Scientists discovered that pregnant women consuming high levels of folic acid were less likely to have children with serious birth defects of the nervous system, such as spina bifida.
Preventing 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-you need to have a sufficient level right at the moment you conceive. Since so many pregnancies are unplanned, health experts recommend that all women of childbearing age take 400 micrograms of folic acid a day.
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.2 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 and close up at the end of the first month of pregnancy. When this fails to 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 children with this defect often suffer from debilitating pain throughout their lives1 and may have difficulty walking.2
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 condition can result in a miscarriage or the infant may die shortly after birth.1
Studies show that if all women in the United States had enough folic acid throughout pregnancy, these birth defects could be reduced by up to 70 percent. By the time a woman is sure she is pregnant, it is too late to prevent birth defects by taking folic acid since the neural tube forms in the first 28 days after conception.2 Women who have been taking folic acid for at least a year before becoming pregnant also reduce the risk for premature birth by half.
Women who could become pregnant or are planning to start a family should consume 400 micrograms of folic acid every day. It is recommended that they increase their daily consumption to 600 micrograms during pregnancy and 500 micrograms while breastfeeding.
Alzheimer’s Disease and Memory Loss in Old Age
Until recently, many researchers hoped that taking folic acid might help delay the onset of Alzheimer’s. Alzheimer’s is a disease that begins its attack in the part of the brain that controls memory and thinking skills and slowly spreads to affect other parts of the brain as well.3
In a study done by scientists at the National Institute of Health, mice were bred to have brain abnormalities that are typical in Alzheimer’s patients. Some of the mice were fed diets low in folic acid and others were given a diet rich in folic acid. Mice that had diets rich in folic acid were able to repair DNA in the nerve cells damaged by Alzheimer’s better than mice that did not have diets rich in folic acid.4
Unfortunately, research on Alzheimer’s patients showed no benefit for those taking high doses of folic acid.5 The folic acid reduced homocysteine levels (an amino acid found in the blood), which tend to be high in people with Alzheimer’s and also in people with low levels of folic acid. While folic acid supplements lowered homocysteine levels in the Alzheimer’s patients, this did not translate into better scores on tests of cognitive functioning.
Although folic acid supplements do not help people with Alzheimer’s, they can improve memory and other measures of cognitive functioning among older people with low levels of folic acid. A study carried out in the Netherlands by Jane Durga and her colleagues looked at the effects of giving 800 micrograms of folic acid twice a day to people who were between 50 and 70 years of age and had high homocysteine levels, indicating a folic acid deficiency.6 The study lasted three years and tested the participants on their ability to pay attention, to recall information, and on their language skills. The individuals who took the high doses of folic acid showed improvements in memory skills and information processing speed as compared with the study participants who took a placebo.
While this seems like an encouraging finding, it might not be relevant to people in the U.S. The study took place in the Netherlands, where food is not fortified with folic acid. In the U.S., it is required that foods made from grains be enriched with folic acid. This is why folic acid deficiency is less likely to occur among people in the U.S., except among people with low anemia, alcoholism, liver disease, or who are undergoing kidney dialysis.7 Some medicines can also interfere with the body’s ability to absorb this nutrient. What the study from the Netherlands does not tell us is whether large doses of folic acid can help improve memory skills and other measures of mental acuity in older people who do not have high homocysteine levels and low levels of folic acid.
How to Make Sure You Have Enough Folic Acid
How do you get folic acid into your diet? Folic acid is the synthetic or man-made version of folate, a naturally occurring B vitamin. Synthetic folic acid is better absorbed and used by our bodies than naturally occurring folate, because about 85% of folic acid in fortified foods and 100% of folic acid in vitamins are absorbed by the body, while only 50% of folate in foods is absorbed by the body. There are many sources of folate, although cooking and storage can destroy it.8 In addition to leafy greens like spinach, many other vegetables and fruits are high in folate, such as citrus fruits, broccoli, bananas, peas, and beans.9
Most daily multivitamin pills contain the recommended daily amount (400 micrograms) of folic acid. In the United States, enriched grain products such as cereal, flour, pasta, rice, and white bread are fortified with folic acid. Fortified white bread actually 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.1 Sugary cereals and many popular adult cereals also contain folic acid, but usually only up to 100-200 mcg per serving. Breakfast bars contain even less. 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 should be sure to take vitamins with folic acid since they don’t consume as much folic acid from fortified grains.
Is it possible to get too much folic acid?
Consuming more than 1000 mcg of folic acid daily, more than double the recommended amount, can hide a vitamin B-12 deficiency because of the similar roles the different B vitamins play in the body. A vitamin B-12 deficiency can cause irreversible nerve damage over time. However, there is not much chance of a woman getting too much folic acid unless she is taking more than one supplement containing folic acid every day. Most American women only consume about half of the daily recommended amounts of folic acid.2
The bottom line is that folic acid is extremely important for fetal health, and making sure pregnant women get the appropriate amounts is an easy way to protect their unborn child’s health. The best way to do that is to make sure that all women of reproductive age are consuming folic acid, not just those who are planning to get pregnant.
 Centers for Disease Control. Folic Acid Frequently Asked Questions. http://www.cdc.gov/ncbddd/folicacid/faqs.html. January 30, 2008.
 March of Dimes. Preconception Risk Reduction: Folic Acid. http://www.marchofdimes.com/professionals/19695_1151.asp#head2. February 2010.
 Alzheimer’s Disease Educational & Referral Center. General Information. http://www.nia.nih.gov/Alzheimers/AlzheimersInformation/GeneralInfo/. July 24, 2008.
 National Institute of Health. Folic Acid Possibly A Key Factor In Alzheimer’s Disease Prevention. http://www.nih.gov/news/pr/mar2002/nia-01.htm. March 1, 2002.
 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.
 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.
 Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Folate. http://ods.od.nih.gov/factsheets/folate.asp. August 2005.
 WomensHealth.gov. Folic Acid; Easy to Read. http://www.womenshealth.gov/faq/folic-acid.pdf. May 2010.
 March of Dimes. Pregnancy and Newborn Health Education Center: Folic Acid. http://www.marchofdimes.com/pnhec/173_769.asp. February 2010.