The proportion of babies born with neural tube defects such as spina bifida in the province of Newfoundland and Labrador dropped by 78 per cent after the Canadian government in 1998 directed that folic acid must be added to flour, cornmeal and pasta.
While the precise way that folic acid works to reduce the risk of neural tube defects in developing babies is poorly understood, a growing body of science suggests strong benefits to women of childbearing age.
Since 1992, many health organisations have recommended that women take 400 micrograms of supplemental folic acid per day before conception and in the early weeks of pregnancy.
European governments have largely resisted calls to fortify foods, concerned about the possible side-effects of a wide-ranging fortified food initiative. A two-year investigation into flour fortification by the UK's Food Standards Agency concluded in 2002 that this could mask a deficiency of vitamin B12 in elderly people.
But Dr. Catherine McCourt, from the Population and Public Health Branch, Health Canada, that led the Canadian study said their findings "provided no evidence for a deterioration in vitamin B12 status in seniors, and no evidence that improved levels of blood folate masked this vitamin deficiency."
The incidence of neural tube defects in the province reduced from an average of 4.36 defects per 1000 births between 1991 and 1997, prior to fortification, to an average of 0.96 defects per 1000 births between 1998 and 2001, once fortification was introduced.
Of particular interest to the supplement industry, over the study period the number of women aged between 19 and 44 who took folic acid supplements rose significantly from 17 per cent to 28 per cent.
As a result of this increasing use in supplements, the full weight of Canada's food fortification measures are harder to measure and the authors stress that "public education regarding folic acid supplement use by women of childbearing age should continue."
Cost and technical issues still present concerns for the food industry over flour fortification that means buying nutrients, new equipment, further testing and quality control, and marketing spend. With little government support, both the private sector and consumers must bear some of these additional costs.
Speaking at this year's World Economic Forum, current chair of GAIN Jay Naidoo, also chairman of the board of the Development Bank of Southern Africa, said that if wheat flour was fortified in the 75 most needy countries with iron and folic acid, iron deficiency could be reduced by 10 per cent, and birth defects could be lowered by a third.
Such fortification would cost a total of about $85 million, or about 4 cents per person, he said.
Full findings of the folic fortification study are published in the September issue of BMC Pregnancy and Childbirth.