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Cat. No.: H164-109/2-2009E-PDF (PDF Version)
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FolateFootnote 1, a B vitamin, plays an important role in cell division and in the synthesis of amino acids and nucleic acids like DNA (Antony, 2007). It is essential to the normal development of the spine, brain and skull of the fetus, especially during the first four weeks of pregnancy. This is a time when many women are not yet aware that they are pregnant. Folate also supports the pregnant woman's expanding blood volume and growing maternal and fetal tissues (IOM, 1998).
Key Messages On Folate For Women Of Childbearing Age
Folate requirements have been set mainly based on the amount of dietary folate equivalents (DFEs)Footnote 2 needed to maintain normal red blood cell concentrations (IOM, 1998). The Recommended Dietary Allowance (RDA)Footnote 3 for women of childbearing age is 400 mcg DFEs (IOM, 1998). In addition to dietary folate intake from a varied diet, all women who can become pregnant should take a multivitaminFootnote 4 containing 400 mcg (0.4 mg) of folic acid every day. This reduces the risk of neural tube defects (Van Allen et al., 2002).
Folate requirements increase during pregnancy. There is a dramatic acceleration in cell division and red blood cell development as the uterus enlarges, the placenta develops, maternal blood volume expands, and the fetus grows (IOM, 1998). The mother also transfers folate to the fetus (Antony, 2007). Evidence supports a RDA of 600 mcg DFEs per day to maintain normal folate status during pregnancy (IOM, 1998).
Because the body has a high demand for folate, women may not get enough of this nutrient during their childbearing years (Power, 2005; Ortega et al, 2006; Sherwood et al, 2006; Kirkpatrick and Tarsuk, 2008). Women who are at higher risk include those who:
Neural tube defects (NTDs)Footnote 6 include spina bifida and anencephaly. They occur when the neural tube fails to close properly during the third and fourth week of pregnancy. Often a woman doesn't yet know that she is pregnant during this critical time. A decreased risk of NTD is associated with both increased folate intake and higher red blood cell folate concentrations (greater than 906 nmol/L); though the experimental evidence is stronger for increased folate intake and NTD risk reduction (IOM, 1998).
The risk is reduced when women start taking a daily multivitamin containing folic acid three months before the beginning of pregnancy and continuing in early pregnancy while the neural tube is closing (from 21 to 28 days after conception, or the 6th week after the beginning of the last menstrual period)Footnote 7 (Van Allen et al, 2002). The reduced risk has been observed in women who took a supplement containing 360 to 800 mcg of folic acid per day, in addition to an intake of 200 to 300 mcg per day of natural folate (IOM, 1998).
Many studies also show that multivitamins containing folic acid taken in the early weeks of pregnancy are associated with a decreased risk of oral cleft and cardiovascular anomalies (IOM, 1998; Cziezel et al, 1999; Cziezel, 2004; Eichholzer et al, 2006; Goh et al, 2006). Some evidence also suggests an association with reduced risk of preeclampsia (Bodnar et al, 2006; Wen et al, 2008). This is an area of active and on-going research.
In light of this evidence, and recognizing that pregnancies are not always planned, the Government of Canada has taken steps to help women of childbearing age increase the amount of folate they consume through mandatory food fortification and the promotion of vitamin supplementation for all women who could become pregnant.
Adding folic acid to white flour, enriched pasta, and enriched corn meal has been mandatory in Canada since November 1998. Studies show that this measure has increased folate intake and improved folate status in Canadian women of childbearing age (Ray et al, 2002; Liu et al, 2004). This population health approach has also been associated with a significant reduction in the rate of NTDs. For example, a 7-province study (from 1993 to 2002) showed a reduction of 46% in the overall rate of NTDsFootnote 8 post-fortification (De Wals et al, 2007).
Considering that the level of intake of folic acid from fortified foods is estimated to be no more than 100 to 200 mcg per dayFootnote 9, and recognizing that many pregnancies are unplanned, all women who could become pregnant should take a multivitamin containing 400 mcg (0.4 mg) of folic acid daily. This is in addition to the dietary folate provided by a varied diet. Having women supplement their diets with folic acid between pregnancies can help reduce the risk of NTDs in subsequent births.
Some women, such as those who have had a previous NTD affected pregnancy and those with a near relative who has a NTD, are at higher risk of having a NTD-affected pregnancy. They may need more than 400 mcg (0.4 mg) of folic acid daily (Van Allen and McCourt, 2002). These women should be assessed early and advised on the steps to take to prepare for a healthy pregnancy.
According to Canadian survey data, 58% of women said they took a multivitamin containing folic acid or a folic acid supplement in the three months before becoming pregnant (Public Health Agency of Canada, 2009). It has been shown that the use of supplements is influenced by economic status and educational background (Botto et al, 2005). For instance, the use of folic acid supplements before pregnancy in Canada was lowest among women in lower-income households, among women with less than high school graduation, and among immigrant mothers (Millar, 2004). Women with unplanned pregnancies, mothers under the age of 25 and single mothers are also less likely to supplement with folic acid (Ray et al, 2004).
Although the majority of Canadian women take folic acid supplements in the three months before pregnancy, continued public health efforts are needed to promote awareness of the importance of folic acid supplementation for all women of childbearing age. To avoid increasing socio-economic inequalities in folic acid use, interventions should provide practical support to vulnerable groups (Stockley and Lund, 2008).
Canadian survey data show that it is difficult for most women of childbearing age to consume enough folate from diet alone to meet their pregnancy needs. Over 75% of non-pregnant/non-breastfeeding women aged 19 - 50 have intakes less than the Estimated Average Requirement (EAR)Footnote 10 for pregnancy, 520 mcg of DFEs (Health Canada, 2008). To meet folate needs during pregnancy, women should consume a varied diet that provides dietary folate (see Table I), and continue taking a multivitamin containing 400 mcg (0.4 mg) of folic acid throughout their pregnancy.
|Food||1 Food Guide Serving||MicrogramsTable 1 footnote a of folate as dietary folate equivalents (µg DFEs)|
Table 1 footnotes
|Lentils and romano beans||175 mL||265-270|
|Black beans||175 mL||190|
|White beans||175 mL||125|
|Asparagus and spinach, cooked||125 mL||120|
|Salad greens, such as Romaine lettuce, mustard greens and endive||250 mL||80-110|
|Pinto beans, kidney beans and chickpeas||175 mL||70-100|
|Pasta made with enriched wheat flour||125 mL||90|
|Sunflower seeds, shelled||60 mL||80|
|Bagel made with enriched wheat flour||½ bagel (45 g)||60-75|
|Brussels sprouts, beets and broccoli, cooked||125 mL||70|
|Bread made with enriched wheat flour or enriched corn meal||1 slice or Ż pita or Ż tortilla (35 g)||45-65|
|Spinach, raw||250 mL||60|
|Orange juice from concentrate||125 mL||60|
|Peanuts, shelled||60 mL||45|
|Green peas||125 mL||40|
|Raspberries, strawberries, blackberries||125 mL||15-35|
|Enriched ready to eat cereal||30 g||10-35|
|Broccoli and cauliflower, raw||125 mL||30|
|Snow peas||125 mL||30|
|Pineapple juice||125 mL||30|
|Walnuts, almonds and hazelnuts, shelled||60 mL||20-30|
|Baby carrots||125 mL||25|
Following a healthy eating pattern and choosing foods that are rich in nutrients helps women meet their requirement for folate and other nutrients. To promote adequate dietary folate intake:
For women who can become pregnant, health care professionals play an important role in motivating them to use supplements (Eichholzer et al, 2006). To ensure proper use of multivitamin supplements:
High doses of folic acid can hide signs of vitamin B12 deficiency. They can also bring on or accelerate neurological complications associated with B12 deficiency (IOM, 1998). As well, women who have low vitamin B12 status are at higher risk for NTD (Van Allen and McCourt, 2002; Ray et al, 2007; Molloy et al, 2009). The prevalence of vitamin B12 deficiency in women of childbearing age is considered very low (IOM, 1998). However, some studies suggest that more women in this life stage group may have low vitamin B12 status than expected (Ray et al, 2008). Women who do not or infrequently consume foods of animal origin and do not take a vitamin B12 containing supplement are most likely to have deficient or marginal vitamin B12 status (Allen, 2009).
Emerging data also suggest there may be additional health risks associated with taking folic acid, including the development of colon cancer when preneoplastic cells are present (Kim, 2006; Ashokkumar et al, 2007; Smith et al, 2008). It is important that health care professionals do not advise higher doses of folic acid than is recommended in this document, unless duly warranted.
Health Canada sincerely thanks the members of the Expert Advisory Group on National Nutrition Pregnancy Guidelines who generously gave their time and expertise over the course of preparing these guidelines:
Health Canada would also like to thank the many stakeholders who took part in the online consultation process and provided feedback on draft content of the guidelines.
The term folate includes both natural folate found in food, and the synthetic form, folic acid, found in fortified foods and vitamin supplements. The term dietary folate is used to describe all forms found in food: natural folate, plus folic acid from fortified foods.
The concept of dietary folate equivalents or DFEs for folate intake attempts to adjust for the bioavailability of natural folate compared to folic acid, as natural folate is thought to be less bioavailable (IOM, 1998).
The Recommended Dietary Allowance or RDA is the average daily dietary nutrient intake that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in a particular life stage and gender group. The RDA for a nutrient can be used as a guide for daily intake (IOM, 2006).
The term 'multivitamin' is used throughout this text as a short form for 'multivitamin/multimineral supplement'.
Food insecurity refers to the limited or uncertain availability of nutritionally adequate and safe foods or limited or uncertain ability to acquire acceptable foods in socially acceptable ways.
For more information on the risk and development of NTDs, see Preconception health: folic acid for the primary prevention of neural tube defects. A resource for health professionals
This is a time when many women are not yet aware of their pregnancy.
Data included births, stillbirths and cases detected prenatally that were subsequently terminated.
These estimates are based on mandated levels of folic acid fortification (Canada Gazette part II, 1998).
The Estimated Average Requirement or EAR is the average daily nutrient intake level that is estimated to meet the requirements of half of the healthy individuals in a particular life stage and gender group. The EAR is the primary reference point for assessing the adequacy of estimated nutrient intakes of groups; it is the basis for calculating the RDA (IOM, 2006).
Some imported grain products, such as pasta, may not be enriched. Most rice is also not enriched.
The Canada Prenatal Nutrition Program is developed and delivered in partnership with the provinces and territories, and with First Nations and Inuit communities. The services provided include food supplementations, nutritional counselling, breastfeeding support, education, referral and counselling on health and lifestyle issues.
Eligible First Nations and Inuit women of childbearing age can access multivitamins through the Non-Insured Health Benefits for First Nations and Inuit.
According to Health Canada's Multi-vitamin/mineral supplement monograph, the vitamin A content per daily dose must not exceed the UL for vitamin A.