Since the FDA authorized adding folic acid to breads, pastas, rice, flour, cereal, and other grain products, the nation has witnessed a 19% drop in devastating birth defects called neural tube defects, according to one of the first studies to look at the impact of the folic acid program.
Neural tube defects, which include spina bifida and anencephaly, affect 4,000 pregnancies each year and result in 2,500-3,000 U.S. births annually. Spina bifida, or open spine, occurs when the backbone never closes completely and is a leading cause of childhood paralysis. Anencephaly is marked by a severely underdeveloped brain and skull.
The findings are published in the June 20 issue of Journal of the American Medical Association.
Increasing folic acid consumption before becoming pregnant and during the first trimester of pregnancy is known to reduce risk for such birth defects. But just 29% of U.S. women were consuming the recommended 400 mcg of folic acid daily. That's why, in 1998, the FDA required that all enriched grain products be fortified with folic acid, providing most people with an added 100 mcg of folic acid daily.
To evaluate the program's success, researchers reviewed birth certificate data for live births in 45 states and Washington, D.C., from January 1990 through December 1999. Before the fortification program began, 37.8 neural tube defects were reported for every 100,000 live births, compared with 30.5 defects for every 100,000 live births after mandatory folic acid fortification began.
"We are viewing the findings as good news," says study author Margaret A. Honein, PhD, MPH, an epidemiologist at the National Center on Birth Defects and Developmental Disabilities at the CDC in Atlanta.
She's not the only one. James L. Mills, MD, and Lucinda England, MD, of the National Institute of Child Health and Human Development in Bethesda, Md., co-wrote an editorial that accompanied the new study.
"This exciting news clearly validates the U.S. government's decision to intervene on a massive scale to prevent these devastating birth defects," they write.
They add, however, that the study findings may be a little off because birth certificate data do not always list birth defects, and certificates don't account for fetal deaths or still births, both of which commonly occur in neural tube defect-affected pregnancies. In addition, many neural tube defects are identified by prenatal screening and subsequently terminated.
Also, the 19% drop is far lower than the 50% reduction that some scientists estimated when the program began, prompting some to wonder if food should be enriched with more folic acid.
"It's a little too soon to be sure [whether more fortification is needed], but probably the answer is yes," says Richard Leavitt, director of science information at the March of Dimes, based in White Plains, N.Y.
An increase in folic acid fortification, however, could trigger an unhealthy consequence: pernicious anemia. This form of anemia, or iron-poor blood, damages the brain and nerves and is caused by a deficiency in vitamin B-12. Increased folic acid levels can interfere with detecting this deficiency.
On the flip side, however, folic acid decreases blood levels of homocysteine. High levels of homocysteine are a risk factor for heart disease. It's conceivable that increased folic acid may lower risk of heart disease, but the evidence is not yet in.
In the meantime, Leavitt says, "if you're sexually active and there's any possibility of pregnancy, you need to be supplementing folic acid because just about half of all pregnancies in this country are unplanned. ... women can't safely wait until they make a definite decision to conceive to start."