Declining Rate of Folate Insufficiency Among Adults Following Increased Folic Acid Food Fortification in Canada

Objective: Canada introduced a mandatory folic acid food fortification program in November 1998. We investigated whether the rate of folate and vitamin B12 insufficiency among adults has changed since this mandatory fortification program was implemented. Methods: We conducted a retrospective cross-sectional study using a large Ontario laboratory database. We included all individuals who underwent evaluation of their serum folate, red cell folate and serum vitamin B12 between April 1, 1997 to July 31, 1998 (Period A), August 1, 1998 to January 30, 1999 (Period B) and February 1, 1999 to March 31, 2000 (PeriodC). Results: A total of 8,884 consecutive samples were analyzed during the period of study. Mean age was 57.4 years (SD 21.1), and 63.2% were female. The prevalence of serum folate insufficiency (below 3.4 nmol/L) fell from 0.52% in Period A to 0.22% in Period C [prevalence ratio (RR) 0.41, 95% confidence interval (CI) 0.18-0.93)]. The prevalence of red cell folate insufficiency (below 215 nmol/L) declined from 1.78% during Period A to 0.41% in Period C (RR 0.23, 95% CI 0.14-0.40). No significant difference was observed between periods in the prevalence of B12 insufficiency below 120 pmol/L (3.93% versus 3.11 %, respectively; RR 0.79, 95% CI 0.62-1.01). Conclusions: There has been a significant decline in the prevalence of folate, but not vitamin B12 insufficiency, following Canadian folic acid food fortification. These changes may have important implications for the prevention and detection of folate and vitamin B12 insufficiency, including identifying the benefits of folie acid food fortification and the need to further consider fortification or supplementation with vitamin B12. Objectif : En novembre 1998, le Canada a lancé un programme d'enrichissement en acide folique obligatoire pour certains aliments. Nous avons voulu déterminer si le taux de carence en folate et en vitamine B12 chez les adultes a changé depuis la mise en oeuvre du programme. Méthode : Étude transversale rétrospective à partir d'une vaste base de données d'un laboratoire ontarien. Nous avons inclus toutes les personnes dont le folate sérique, le folate érythrocytaire et la vitamine B12 sérique ont été évalués entre le 1 er avril 1997 et le 31 juillet 1998 (période A), entre le 1 er août 1998 et le 30 janvier 1999 (période B) et entre le 1 er février 1999 et le 31 mars 2000 (période C). Résultats : En tout, 8 884 échantillons consécutifs ont été analysés durant la période de référ