Delay in fortifying flour with folic acid is unjustified. In many countries this public health measure has increased blood folate levels and reduced neural tube defects. When the effect of folic acid on neural tube defects was shown in 1991, prevention was attempted through diet and supplements.1 But supplements must be taken before pregnancy is confirmed, and most pregnancies remain unprotected.

Voluntary fortification has proved inadequate. Expert advisory committees considering mandatory fortification with folic acid have concluded that it is necessary, effective, and safe; about 40 countries, including the United States, have adopted this policy.

It is important to reach people who are less well off—they have most to gain from fortification. In Chile, where fortification has achieved a relatively high folic acid intake, neural tube defects were reduced by 43%; in the United States, with a lower fortification level, the reduction was about 20%.2 With fortification on a global basis, …