Folic acid supplement use is the most significant predictor of folate concentrations in Canadian women of childbearing age.

One-fifth of Canadian women of childbearing age (WCBA) have red blood cell (RBC) folate concentrations below those considered optimal for neural tube defect risk reduction (≥906 nmol·L(-1)). Determinants of optimal concentrations have not been examined in a nationally representative sample of Canadian WCBA since food fortification with folic acid was implemented. This study explored correlates of optimal RBC folate concentrations and characteristics of folic acid supplement users in a sample of Canadian WCBA. RBC folate concentrations from the 2007-2009 Canadian Health Measures Survey were assessed in women aged 15 to 45 years (n = 1162). Sociodemographic, behavioural, and clinical determinants of RBC folate ≥906 nmol·L(-1) were examined using univariate and separate multiple logistic regression models that controlled for age and household income. t tests were used to study differences between folic acid supplement users and nonusers. WCBA not taking folic acid supplements were less likely to achieve a RBC folate concentration ≥906 nmol·L(-1) compared with folic acid supplement users (odds ratio, 0.47; 95% confidence interval, 0.24, 0.92). Twenty-five percent of WCBA reported folic acid supplement use, and there was a higher percentage of folic acid supplement users in the highest income group. Folic acid supplement users were also more frequent consumers of supplemental vitamin B(12) and of fruit and vegetables (>3 times per day). Folic acid supplement use was the most significant predictor of WCBA achieving optimal RBC folate concentrations. These results indicate a need for targeted strategies to improve compliance with folic acid supplement recommendations among WCBA.