Letters [the Impact of Food Fortification on Folic Acid Intake in Canada] [Criminal Code Sanctions]

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The Impact of Food Fortification on Folic Acid Intake in Canada

Dear Editor:

Re: Ray JG, Vermeulen MJ, Boss SC, Cole DEC. Declining rate of folate insufficiency among adults following increased folic acid food fortification in Canada.

Can J Public Health 2002;93(4):249-53.

In November 1998, Canada introduced a national program by which folic acid was added to all flour, and some corn and rice products, so as to increase folic acid consumption by an estimated 100(mu)g/d. This initiative paralleled a similar program in the US,1 both of which are intended to reduce the occurrence of neural tube defects (NTDs). The study by Ray et al. assessed the effect of fortification on the nutritional status of Canadians, which is an important first step in determining the health impact of this program.

We recently reported an evaluation of published data to determine the relationship between the change in serum folate concentration and folic acid intake.2 A literature review identified four studies (representing a total of 12 treatment regimes) in which folic acid had been consumed daily for periods sufficient for serum folate concentrations to reach equilibrium. From these data, we derived a linear regression equation relating change in serum folate concentration [(Delta)Folate (nmol/L)] to the daily folic acid intervention [FA/d ((mu)g/d)]:

(Delta)Folate = 0.05756 x (FA/d) + 0. 165 (n=12; r=0.984; p <=0.0001)

Using this equation and reverse prediction, it was possible to calculate from observed changes in serum folate concentration the causal change in daily folic acid consumption. This model is internally consistent and is in good agreement with other observational studies. For instance, our estimate that fortification caused an increase in folic acid consumption of 215(mu)g/d in the Framingham Cohort is in good agreement to the estimate of 190(mu)g/d derived3 for the same cohort using food frequency questionnaires and updated food composition tables. On the basis of the change in serum folate concentration reported by Ray et al. for Canadians, we estimate that the Canadian fortification program has increased folic acid consumption by 150(mu)g/d and not the target 100(mu)g/d.

Ray et al. have clearly demonstrated that fortifying cereal grain with folic acid has had the desired effect of increasing folate nutrition and reducing the incidence of deficiency. However, these benefits have been a result of a higher than intended intake of folic acid. While the Canadian level of intake (150(mu)g/d) is considerably less than that estimated for the US (190(mu)g/d^sup 3^ to 245(mu)g/d^sup 2^), it still represents a margin of error within the fortification model. …