Pregnancy often makes us take a closer look at our nutrition. Even if we weren’t taking vitamins in the past, we’re likely to start. At the first appointment with our prenatal care provider, likely we discuss some of the recommended requirements or possibly for those of us that are Type A personalities, we’ve already thoroughly researched the topic because we want to be on top of everything by the time we meet our provider. I recall hearing from a variety of sources that Folic Acid was one of the key important nutrients and to be sure to make sure you were getting enough. But what is enough and is a multi-vitamin the best source of this important nutrient? We’ll take a look at recent research to find out how much is enough, is there such a thing as too much of a good thing, and what are the best sources of folic acid or it’s more natural form, folate.
Folic acid and folate are members of the B vitamin family. Their names come from folium, the Latin word for leaf. (1) It is not a surprise that leafy vegetables are by far the best sources of folate. This nutrient is found naturally in various leafy vegetables such as spinach, cabbage, turnip greens, collard greens, and romaine lettuce. (18) Often the terms folic acid and folate are used interchangeably as in this excerpt from the Baby Center, “If you’re pregnant or might become pregnant, it’s critically important to get enough folic acid, the synthetic form of vitamin B9, also known as folate.” (3) But in fact, folate refers to various tetrahydrofolate derivatives naturally occurring in foods. (6) Folic acid, on the other hand, is the fully oxidized synthetic compound (pteroylmonoglutamic acid) used in dietary supplements and in food fortification. (6)
Human exposure to folic acid was non-existent until its chemical synthesis in 1943. (4) In January 1998, the U.S. Food and Drug Administration (FDA) began requiring manufacturers to add folic acid to enriched breads, cereals, flours, cornmeals, pastas, rice, and other grain products. (13) The overwhelming evidence that folic acid supplementation before conception and during early pregnancy prevents neural tube defects (NTD) in newborns is what led to the FDA requirement. Food fortification rather than supplementation was deemed necessary because NTD’s could occur during early pregnancy, before a women knows she is pregnant.
The neural tube is the part of the embryo from which your baby’s spine and brain develop. If something goes wrong in their development, the result is called a neural tube defect. These are birth defects of the spinal cord (such as spina bifida) and the brain (such as anencephaly). (3) A baby’s neural tube is formed and closed in the first four to six weeks of pregnancy. (10) By the time most women know or suspect they are pregnant, the time for the developing fetus to benefit from extra folate has passed. NTDs affect about 3,000 pregnancies a year in the United States. (3) The Centers for Disease Control and Prevention (CDC) reports that women who take the recommended daily dose of folic acid starting at least one month before conception and during the first trimester of pregnancy reduce their baby’s risk of neural tube defects by up to 70 percent. (3)
Beyond protecting against NTD, folate is a key player in essential cell functions. It helps make, protect, and repair DNA (15), aids the complete development of red blood cells that carry oxygen from your lungs to all parts of your body (and to your baby) (14), and helps convert some amino acids (the building blocks of proteins) into others (15). During pregnancy, women’s requirements increase as baby grows in the womb. The rapid cell growth that takes place in the placenta and as your baby grows makes getting additional amounts of folate important. Some research suggests that folate can also reduce your baby’s risk of cleft lip, cleft palate, congenital heart defects, reduces low infant birth weight, preterm delivery and fetal growth retardation. (3, 13) Not only can this important nutrient protect your baby, there can be benefits for the mother also. It may also reduce your risk of preeclampsia, a serious blood pressure disorder that affects about 5 percent of pregnant women. (3)
Folate is found naturally in a wide variety of foods, including vegetables, fruits and fruit juices, nuts, beans, peas , dairy products, poultry and meat, eggs, seafood and grains. (13) Spinach, liver, yeast, asparagus, and Brussel sprouts are among the foods with the highest levels of folate. (13) For a more detailed list, check out the U.S. Department of Agriculture’s Nutrient Database Web site which lists the nutrient content of many foods and provides a comprehensive list of foods containing folate arranged by nutrient content and by food name.
The federal government’s 2015-2020 Dietary Guidelines for Americans notes that “Nutritional needs should be met primarily from foods (13) and folate is no different. Folic acid was once thought to absorb better in the body than natural folate, but studies have found that a whole foods, folate-rich diet is just as effective. (18) Based on a 2007 study published in the American Journal of Clinical Nutrition, the aggregate bioavailability (the degree to which a substance becomes available to the target tissue) of folates from fruit, vegetables, and liver is approximately 80% of that of folic acid. (16) Therefore, it was decided that the consumption of a diet rich in folate from foods can actually improve the folate status of the population more efficiently that was assumed just a few years ago. In part, this may be because although the body may absorb folic acid faster than it absorbs folate, it must then convert it into folate before it can get to work. (15)
Another consideration is that when getting your folate intake through unfortified food, it comes with a whole host of other vitamins, minerals and as-yet undiscovered phytonutrients that work synergistically in the body. In fortified foods and single supplements, it may be working alone. Therefore, it’s best to get your nutrients from food. (15)
During pregnancy though, due to the increased demands of the fetus, it is difficult to obtain a therapeutic dose strictly through diet and may be best to supplement to ensure that you are getting appropriate amounts. Fortified foods can help correct deficiencies, but they can overdo one nutrient. This may prove to be more detrimental that beneficial. For example, some fortified breakfast cereals contain 100 percent of the recommended daily amount. (3) And some breakfast cereals, nutrition bars, and other fortified foods deliver up to 800 micrograms of folic acid, and that’s about double the recommended daily dose. Studies have more recently emerged which raise concern about the safety of chronic intake of high levels of folic acid from fortified foods, beverages and dietary supplements. It has been shown that many ready-to-eat foods are actually over-fortified with folic acid and that the projected daily folic acid intake from fortified food has been greatly exceeded. (2) In fact, the fortification program was projected to increase folic acid intakes by approximately 100 mcg/day, but the program actually increased mean folic acid intakes in the United States by about 190 mcg/day.(13) Considering this may be in conjunction with a daily prenatal vitamin in pregnancy which typically provides 400 mcg or more, we see how this may exceed the Recommended Daily Allowance.
Let’s take a look at what the recommendations actually are for folic acid. The Recommended Daily Allowance (RDA) is the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals. (13) The intake recommendations for folate and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (IOM) of the National Academies.(13). It states that women of childbearing age should get 400 mcg of natural folate daily. It is recommended that women get 600 mcg during pregnancy, and lactating women get 500 mcg of folate each day. (18) In table 1 below taken from the National Institute of Health, you’ll see that folate is listed as micrograms (mcg) of dietary folate equivalents (DFE’s). This term was developed to reflect the higher bioavailability (the amount of a nutrient that reaches the body’s tissues after it is eaten or the amount that your body absorbs) of folic acid than that of food folate. This chart assumes that at least 85% of folic acid is estimated to be bioavailable when taken with food and that only about 50% of folate naturally present in food is bioavailable.
Table 1: Recommended Dietary Allowances (RDAs) for Folate*
|Birth to 6 months*
||65 mcg DFE*
||65 mcg DFE*
||80 mcg DFE*
||80 mcg DFE*
||150 mcg DFE
||150 mcg DFE
||200 mcg DFE
||200 mcg DFE
||300 mcg DFE
||300 mcg DFE
||400 mcg DFE
||400 mcg DFE
||600 mcg DFE
||500 mcg DFE
||400 mcg DFE
||400 mcg DFE
||600 mcg DFE
||500 mcg DFE
*chart from National Institutes of Health (13)
As discussed previously, while there is no agreement on the extent of difference between folic acid and folate bioavailability, folate bioavailability is more efficient than this chart assumes. So, the concern might be that you are consuming too much folate, but rest assured, you can’t get too much from foods that naturally contain folate. (12) It comes naturally packaged in balance with other micronutrients, and the body regulates its absorption. It is possible, however; to get too much folic acid from man-made products such as multivitamins and fortified foods, such as breakfast cereals.
While low levels of folate present many health concerns, new research is showing that excess levels may be a concern as well. The Institute of Medicine advises not to take more than 1,000 mcg per day of folic acid unless advised by your healthcare provider. (15) Certain situations that may require a higher dosage are: (3)
- Women who are obese appear to be more likely to have a baby with a nueral tube defect.
- Previously pregnant with a baby with a neural tube defect (have a 3-5% chance of having another pregnancy complicated by an NTD.
- Carrying twins
- Methylenetetrahydrofolate reductase (MTHFR) mutation – that makes it more difficult to process folate and folic acid (about 50% of women in the U.S. are unable to methylate or fully convert folic acid to folate because of one of more defects in their MTHFR gene (19) )
- Diabetic or taking certain antiseizure medications
Studies show that the body can’t properly process a high intake of folic acid into folate. It is possible that unconverted folic acid circulating in the bloodstream could elbow aside folate for spots inside binding enzymes, carrier proteins, and binding proteins. (16) In theory, this could decrease the amount of folate carried into brain and other tissues—like dying of starvation in a land of plenty. In practice, though, whether this is a real problem is not clear yet. (16)
Looking more specifically at MTHFR issues, this mutation makes it more difficult for the body to detoxify. During pregnancy this is especially concerning because the build up of unusable folic acid (from fortified food and certain prenatal vitamins) can cause toxicity and folate deficiency because it blocks absorption of naturally occurring folate. (20)
Multiple studies have been released in the past few years expressing health concerns about excess folic acid consumption. One of those studies presented preliminary findings in 2016 and suggests that excessive amounts of folate (vitamin B9) and vitamin B12 in a mother’s body might increase a baby’s risk of developing an autism spectrum disorder. (9) The researchers found that if a new mother has a very high level of folate right after giving birth – more than four times what is considered adequate – the risk that her child will develop an autism spectrum disorder doubles. (9) Very high vitamin B12 levels in new moms are also potentially harmful, tripling the risk that her offspring will develop an autism spectrum disorder. If both levels are extremely high, the risk that a child develops the disorder increases 17.6 times. (9)
While this may spark concern in new mothers, it’s important to view the new findings with perspective. M. Daniele Fallen, PhD, director of the Bloomberg School’s Wendy Klag Center for Autism and Developmental Disabilities and the study’s senior author urges us to remember that “Adequate supplementation is protective: That’s still the story with folic acid.” (9) She feels that this study tells us “that excessive amounts (of folic acid) may also cause harm. We must aim for optimal levels of this important nutrient.” (9) In other words, more research needs to be done. It still needs determined just how much folic acid a woman should consume during pregnancy to provide optimal blood folate levels for the best outcome for her baby.
Additional studies point to other concerns of excess folic acid during pregnancy. A 2015 Portugese study published in the Journal of Edocrinology expresses a concern that excessive amounts of folic acid during pregnancy may predispose their daughters to diabetes and obesity later in life. (11) This study also calls for a need to establish a safe upper limit of folic acid intake for pregnant women.
A few studies have also suggested that excess folic acid may be associated with increased risk for colorectal, breast, and prostate cancers. (15) While these studies are limited, they sound an additional warning about getting too much folic acid and confirms that this topic certainly deserves further investigation.
Despite mounting studies about the concerns of excess folic acid and statistics from the CDC that indicate on the other end of the spectrum that one in four women of reproductive age in the U.S. have insufficient folate levels (8), it’s surprising that levels are not routinely monitored during pregnancy. Likely testing was previously thought not to be needed once food fortification requirements were put into place to raise levels of folic acid in women of childbearing age. Since conventional belief is that B vitamins are water soluble it was thought that any excess would be flushed out. Until recently, there wasn’t a concern about high levels in the body.
As discussed previously, most folic acid cannot be converted into the active folate 5-MTHF, and instead it is converted in the liver, or other tissues in the body. (18) While both folate and folic acid need to be converted into the bioactive MTHF for the body to use, it’s easier to convert when it comes from food. (19) The process of converting folic acid is very slow and has been shown to be even worse when fortified foods and folic acid supplements are consumed together. (18) When this happens, it can lead to unmetabolized folic acid in the bloodstream. (18) Possibly as more studies are done to find a safe upper limit of folic acid regular testing will be included in a future prenatal panel checklist to ensure optimum levels. Keep in mind though that by the time you know you are pregnant, it may be too late, so it may be better to be proactive and get testing beforehand if you want to know for sure.
It’s clear that the science is not settled on this issue, so what’s an expecting mama to do regarding folate intake? T.H. Chan of the Harvard School of Public Health recommends to continue taking your standard (prenatal) multivitamin, but to stay away from heavily fortified foods that deliver a full day’s dose – or sometimes more – of folic acid. (15) If eating fortified foods, Chan recommends avoiding foods fortified with more than 100-200 micrograms of folic acid (25% to 50% of the % Daily Value). (15) While no supplement can replace the synergistic effects of whole foods, it’s a great insurance policy, especially when trying to conceive, during pregnancy and lactation. There are now high quality prenatals that contain folate – the natural methylated form, 5-methyltetrahydrofolate (5-MTHF) on the market.
Seeking Health, Optimal Prenatal
Zahler Prenatal + DHA
You can get more info about nutrient profiles of prenatals in this blog post by Mama Natural.
Prenatal vitamins containing l-methylfolate have been compared with ones containing folic acid during pregnancy and the results are mixed. Some experts say that new research will eventually change the guidelines for women, while others say there’s not a compelling case to do so. The choice is yours until more clear information is provided, but as always, be sure to check with your doctor or midwife before making any changes. Let us know what you decide in the comments.
Holly Keich, LSW is the owner of Om Baby Pregnancy & Parenting Center in Camp Hill, PA. When she became pregnant with her first child she began teaching prenatal yoga classes that impart not only the wisdom of poses for the childbearing year, but also knowledge of the spiritual and emotional process of becoming a parent. Holly has attended pre and postnatal yoga teacher trainings with Stephanie Keach and Mindful Mamas. She has also attended Baby Om Yoga training in NYC and is a Certified ChildLight Yoga Instructor, including Baby & Toddler Yoga as well as a Certified Infant Massage Instructor. She supports mother, child & family connections through the opening of Om Baby in 2008.