Fortify to Prevent Brain and Spine Birth Defects
All people need folic acid (vitamin B9) to produce and maintain healthy cells and prevent folate deficiency anemia. In addition, fortifying wheat flour with folic acid lowered plasma homocysteine levels in Australian adults.
Women especially need folic acid to reduce the risk of brain and spine birth defects called neural tube defects (NTDs). These include spina bifida, anencephaly, and cephalocele. They often cause early death or lifelong disability. (The illustration below is courtesy of the US Centers for Disease Control and Prevention (CDC).
In spina bifida, the baby’s spine does not form correctly. In mild cases, permanent loss of some sensation or movement occurs. Severe cases include paralysis and varying degrees of loss of bowel and bladder control. Children born with spina bifida will undergo a lifetime of surgeries and face many health issues. Spina bifida cannot be cured.
With anencephaly, the brain does not form properly. Pregnancies affected by anencephaly are often miscarried. Babies born with anencephaly die shortly after birth.
With cephalocele, part of the brain protrudes through the skull. This is a rare birth defect.
Fortifying flour with folic acid is credited with preventing 50,270 of these birth defects in 2017 for an average of 137 a day . Only about one-third of the world’s flour from industrial mills is fortified, however, so this is only 18% of the NTDs that might be prevented . One study shows that 71 countries have the immediate potential to fortify wheat flour and prevent 57,000 birth defects of the brain and spine annually .
Many brain and spine birth defects are prevented if women have 400 micrograms of folic acid daily at least one month before conception and in the early stages of pregnancy . These birth defects occur within the first four weeks of pregnancy. If women wait until they learn they are pregnant to take folic acid supplements, it is often too late for folic acid to have the protective effect.
Fortifying food increases folic acid intake without requiring consumers to change their behaviors. One meta-analysis showed that fortifying wheat flour with folic acid reduced the incidence of NTDs by an average of 46%. 
Globally an estimated 260,100 NTDs occured in 2015 . About half of these resulted in terminations of pregnancy or still births. Of the live births, about 75% resulted in death before the child's fifth birthday.
Countries that fortify flour with folic acid report that their NTD prevalence before fortification ranged from 3.8 to 43.7 per 10,000 births. This became less variable after flour was fortified with folic acid (3.0 - 24.3 per 10,000 births) .
Some foods such as spinach and liver are rich in vitamin B9 which is called folate in unfortified foods. However, folate is not easily absorbed, making it "difficult for a woman to eat enough natural food folate to prevent neural tube defects" .
For example, to consume the recommended amount of food folate equivalents, a person would need to eat:
- 23 spears of cooked asparagus or
- 4 cups of cooked okra or
- 4 cups for raw spinach or
- 2 slices of beef liver or
- 6 cups of orange juice or
- 4.5 cups of cooked broccoli 
Some people have been told to avoid folic acid because they have a variation of the MTHFR (methyltetrahydrofolate reductase) enzyme. These individuals process folic acid more slowly than those without the variation, and the CDC recommends that people with the MTHFR variation continue to take folic acid.
A review of the safety of folic acid published in 2018 noted that, "Current folic acid fortification programs support public health in populations, and the exposure levels are informed by and adherent to the precautionary principle." Also see this literature review from December 2016.
For additional information, see Folate Status in Women and Neural Tube Defect Reduction.
 Kancherla, V. et al., A 2017 global update on folic acid‐preventable spina bifida and anencephaly. Birth Defects Research Part A: Clinical and Molecular Teratology. 2018.
 Facts About Folic Acid. U.S. Centers for Disease Control and Prevention
 Blencowe, H.et al. “Folic Acid to Reduce Neonatal Mortality from Neural Tube Disorders.” International Journal of Epidemiology. 2010.
 Blencowe, H.et al. "Estimates of global and regional prevalence of neural tube defects for 2015: a systematic analsys." Anals of the New York Academy of Sciences. 2018.
 Food Fortification Initiative. Fortifying Flour with Folic Acid to Prevent Neural Tube Defects.
 Marchetta, C.M. et al., Assessing the association between natural food folate intake and blood folate concentrations: a systematic review and Bayesian meta-analysis of trials and observational studies. Nutrients. 2015.
 Suitor & Bailey., Dietary folate equivalents: Interpretation and application. Journal of the American Dietetic Association, 2000.