On Jan. 10, the U.S. Preventive Services Task Force (USPSTF) published its final recommendation statement(www.uspreventiveservicestaskforce.org) and evidence summary(www.uspreventiveservicestaskforce.org) on folic acid supplementation to prevent neural tube defects. The task force recommended that all women who are planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400 to 800 µg) of folic acid -- an "A" recommendation.(www.uspreventiveservicestaskforce.org)
"The task force found convincing evidence that the risk of neural tube defects can be reduced when women take a daily folic acid supplement of 400 to 800 micrograms," said USPSTF member Alex Kemper, M.D., M.P.H., M.S., in a news bulletin.(www.uspreventiveservicestaskforce.org) "These supplements can be taken as a daily multivitamin, prenatal vitamin or single tablet that has the recommended amount of folic acid."
- On Jan. 10, the U.S. Preventive Services Task Force published its final recommendation statement and evidence summary on folic acid supplementation to prevent neural tube defects.
- The task force recommended that all women who are planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400 to 800 µg) of folic acid -- an "A" recommendation.
- The AAFP released its own final recommendation statement that paralleled the task force's recommendation.
This final recommendation reaffirms the USPSTF's 2016 draft recommendation, as well as the final recommendation it issued in 2009.
The AAFP released its own final recommendation statement that paralleled that of the task force.
Recommendation Details and Scope
As noted when the draft version of this current recommendation was released, the recommendation applies to all women who are planning a pregnancy and those who are capable of becoming pregnant. Women who had a previous pregnancy that was affected by a neural tube defect require special management and are not within the scope of this recommendation.
Folic acid occurs naturally in a number of foods and others are fortified with folic acid, as called for in an FDA regulation that took effect in 1998. But even women who consume these foods most often fail to reach the daily minimum recommended dose of 400 µg.
Although all women of childbearing age can have a pregnancy affected by a neural tube defect and should take folic acid supplements, particular risk factors include
- a personal or family history of neural tube defects;
- use of certain antiseizure medications, such as valproic acid and carbamazepine;
- mutations in folate-related enzymes;
- maternal diabetes; and
Moreover, evidence suggests that some racial/ethnic groups may have a higher risk for neural tube defects. Mexican-American women, in particular, may be at increased risk because of lower consumption of folic acid-fortified foods.
Hispanic women may also be at heightened risk because they are more likely to have a genetic polymorphism that appears to predispose them to decreased intracellular folate metabolism.
To update its 2009 final recommendation, the USPSTF evaluated one randomized, controlled trial; two cohort studies and eight case-control studies for evidence of effectiveness of folic acid supplementation. All were judged to be of fair quality, and three of the case-control studies reviewed specifically examined the effects of folic acid supplementation by race/ethnicity.
The task force did not review evidence on folic acid supplementation in women with a history of pregnancy affected by neural tube defects or other high-risk factors. Evidence on folic acid fortification, counseling to increase dietary intake of folic acid or naturally occurring food folate, and screening for neural tube defects are also outside the scope of this review.
Response to Public Comment
A draft version of this recommendation statement was posted for public comment on the USPSTF website from May 10 to June 6, 2016.
Some commenters requested a more detailed definition of "excessive" folic acid. In response, the task force added information about tolerable upper intake levels for folic acid.
Referencing data from the National Academy of Sciences Food and Nutrition Board, the USPSTF said the tolerable upper intake level of folic acid in women age 19 and older is 1 mg/d (1000 µg/d) from supplements or fortified food and 0.8 mg/d (800 µg/d) for those ages 14-18. The task force also noted that fewer than 3 percent of girls and women ages 14-50 receive more than 1 mg/d (1000 µg/d) of folic acid from supplements or food.
Other commenters suggested adding language on the potential harms of folic acid supplementation -- which the USPSTF incorporated into the final recommendation statement -- and emphasizing that many women don't meet daily recommended amounts of folic acid. Noting that an analysis of National Health and Nutrition Examination Survey data found that less than half of respondents of childbearing age reported consuming the recommended amount of folic acid from mandatorily fortified foods, task force members also took that suggestion to heart.
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