Since 1998, the Food and Drug Administration has mandated all enriched grains to be fortified with folic acid, a B vitamin, in an effort to prevent neural tube defects. Now, 16 years later, a study from the Centers for Disease Control and Prevention (CDC) finds that rates of the serious birth defect have dropped by 35 percent.

The study found that grains fortified with folic acid contributed to an estimated 1,300 fewer neural tube defects (NTD) each year since the mandate’s implementation. NTDs typically develop within the first month of pregnancy, when the neural tube starts out shaped like a ribbon and expands in the spine and brain into a tube. When the tube doesn’t completely close, it can cause birth defects like spina bifida and anencephaly, which are sometimes characterized by the neural tube protruding through gaps in a child’s spine or an incompletely developed head, respectively.

NTDs develop early enough in pregnancy that many women won’t even realize they’re pregnant before the defect has emerged. The FDA’s mandate was implemented to ensure women were getting at least some folic acid in their diets. Studies have shown that women capable of getting pregnant were at a 50 to 70 percent lower risk of having a baby with a NTD if they took 400 micrograms of folic acid each day. However, according to the March of Dimes Foundation, fortification may not be enough.

"All women capable of having a baby should be taking a multivitamin containing folic acid every day," said Dr. Siobhan M. Dolan, co-author of the March of Dimes book Healthy Mom, Healthy Baby: The Ultimate Pregnancy Guide, in a press release about the study. "It's also good to eat foods that contain folate, the natural form of folic acid, including lentils, green leafy vegetables, black beans, and orange juice, as well as foods fortified with folic acid, such as bread and pasta, and enriched cereals."

For the study, the CDC looked at surveillance reports on NTDs from 19 different populations around the country between 1995 and 2011. It found that NTD rates had fallen among all groups observed: non-Hispanic whites, non-Hispanic blacks, and Hispanics. However, Hispanic women were at a “consistently greater” risk of having a baby with an NTD. The researchers suspect this is because Hispanics are more likely to use corn masa flour in their food rather than all-purpose flour.

“To target Hispanics who might need additional folic acid intake to prevent NTDs, one strategy under consideration in the U.S. is to fortify corn masa flour with folic acid at the same level as enriched cereal grain products,” the report said. “Implementation of corn masa flour fortification would likely prevent an additional 40 cases of NTDs annually”

Source: Williams J, Mai C, Mulinare J, et al. Updated Estimates of Neural Tube Defects Prevented by Mandatory Folic Acid Fortification — United States, 1995–2011. Morbidity and Mortality Weekly Report. 2015.