In the linked study (doi:10.1136/bmj.b1673), Ionescu-Ittu and colleagues investigate whether the 1998 government policy for mandatory fortification of flour and pasta products with folate reduced the prevalence of severe congenital heart disease at birth in Quebec, Canada.1 In 1997 the Teratology Society recommended folic acid supplementation to reduce the risk of neural tube defects through the fortification of staple foods. The aim was to ensure that 95% of women of child bearing age received 0.4 mg folic acid daily, with an additional 0.4 mg for those planning a pregnancy.2 Although the potential role of folic acid in the prevention of neural tube defects was reported as early as 1980, public health campaigns resulted in preconception supplementation in only a third of pregnant women.3

The fortification policy was influenced by a Hungarian trial that reported a 90% reduction in primary neural tube defects in pregnancies supplemented by periconceptional multivitamins containing 0.8 mg folic acid.4 Canada initiated mandatory food fortification in 1998, and fortification of wheat flour is currently practised in 67 countries (47 in response …