Optimal Folate Concentrations for Birth Defect Prevention Identified

August 6, 2014

Folic acid (vitamin B9) can prevent neural tube defects, but how much is needed to substantially reduce risk? Find out here.

A blood test measuring folate concentrations may help identify at-risk populations and offer a way to target neural tube defect prevention efforts, researchers suggested in a study recently published in BMJ.

If childbearing women were to take just 400 µg/d of folic acid, ideally before becoming pregnant, the number of neural tube defects could be reduced by 80%, according to an accompanying editorial.

Pertinent Points

- Researchers have shed light on the relationship between red blood cell folate concentrations and the risk of neural tube defects, providing a marker for identifying at-risk populations for public health prevention efforts.

- The analysis showed that RBC folate concentrations above about 1000 nmol/L reduced the risk of folate-sensitive neural tube defects, and that concentrations above about 1300 nmol/L provided limited additional risk reduction.

With a goal to determine the optimal red blood cell (RBC) folate concentrations needed to prevent neural tube defects, the researchers were able to show that the risk was substantially reduced in women with higher concentrations. Specifically, RBC folate concentrations above about 1000 nmol/L were consistent with an optimal reduction in the risk, the authors reported. In addition, they reported a limited additional risk reduction with concentrations above about 1300 nmol/L.

In conducting the study, the researchers relied on data from two studies in non-folate–fortified regions in China. One of the studies included data from 247,831 participants of a neural tube defect prevention program and the other included a randomized trial of 1,194 women with no plans to become pregnant that evaluated the effect of folic acid supplements on blood folate concentrations.

By determining an optimal threshold level, the authors suggested that clinical blood tests could help in the evaluations of prevention programs and in recognizing which subpopulations might be at an elevated risk for neural tube defects. The findings could help guide policy decisions by giving public health leaders a tool for lowering the number of preventable neural tube defects worldwide, researchers from Nuffield Department of Population Health at the University of Oxford wrote in an editorial accompanying the study.

In the United States, the study authors suggest that there remain public health implications despite the folic acid fortification efforts that have successfully helped lower the risk of neural tube defects. Given that many US women do not begin taking folic acid supplements until after confirming a pregnancy, the authors say the blood test could help in understanding those who are at increased risk for neural tube defects.