The challenge
Neural-tube defects such as spina bifida are serious birth defects, and in Canada they were historically more common in the eastern provinces than the western ones.
The case
In 1998 Canada made folic acid fortification of a large variety of cereal products mandatory. Researchers led by Philippe De Wals studied 1.9 million births, stillbirths and terminations for fetal anomalies in seven provinces from 1993 to 2002. The prevalence of neural-tube defects fell from 1.58 per 1,000 births before fortification to 0.86 per 1,000 once it was fully in place, a 46% reduction. Spina bifida fell 53%, anencephaly 38% and encephalocele 31%. The biggest falls came in the eastern provinces, which had the highest rates before, and regional differences almost disappeared.
Why it worked
Adding folic acid to everyday foods was associated with a large fall in these birth defects across Canada. The study compared periods before and after fortification, so it shows a strong association rather than a randomised result.
Sources
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