Prevalence and correlates of folic acid supplement use in Canada.

Dietary supplements are an important source of folic acid, a nutrient that is vital in reducing the risk of neural tube defects. As part of the 2007 to 2009 Canadian Health Measures Survey, data were collected on supplement use, and biomarkers were directly measured. Use of supplements that contain folic acid was reported by 25% of Canadians aged 6 to 79. Females were more likely than males to report taking folic acid supplements. People who ate fruit and vegetables less than once a day had significantly lower odds of taking folic acid-containing supplements than did those who ate fruit and vegetables at least three times a day. Of those who consumed a folic acid supplement, 91% reported also taking a supplement that contained vitamin B12. Red blood cell folate concentrations below the median (less than 1,248 nmol/L), low-to-marginal serum vitamin B12 concentrations (221 pmol/L or less), and high concentrations of plasma homocysteine were negatively correlated with folic acid-containing supplement use.