A team from Atlanta, Georgia, USA, evaluated the impact of food fortification with folic acid on the birth prevalence of neural tube defect (NTD).
They conducted a national study of birth certificate data for live births to women in 45 US states.
|19% reduction in neural tube defects following US folic acid fortification.
Birth certificate reports of spina bifida and anencephaly before fortification (October 1995 to December 1996) were compared with reports after mandatory fortification (October 1998 to December 1999).
The birth prevalence of NTDs reported on birth certificates decreased from 37.8 per 100,000 live births before fortification, to 30.5 per 100,000 live births conceived after mandatory folic acid fortification. This represented a decline of 19%.
During the same period, NTD birth prevalence declined from 53.4 per 100,000 to 46.5 per 100,000 (13% decline), for women who received only third-trimester or no prenatal care.
Dr Margaret A. Honein, of the Centers for Disease Control and Prevention, Atlanta, concluded on behalf of the group, "A 19% reduction in NTD birth prevalence occurred following folic acid fortification of the US food supply.
"However, factors other than fortification may have contributed to this decline."
In an accompanying editorial, James L. Mills and colleagues, say that the study provides important evidence that food fortification works.
Dr Mills, of the National Institute of Child Health and Human Development, Bethesda, Maryland, comments, "Birth certificate data can, however, provide only imprecise estimates of how well food fortification works."
"This is due to several limitations of using such data. One limitation is that national birth certificate records do not include fetal deaths or stillbirths, both of which are common in NTD-affected pregnancies," he adds.
"Much hard work lies ahead to determine how many cases of NTD are actually being prevented," he concludes.