Introduction Canadians' red blood cell (RBC) folate has shifted towards high concentrations (>1360 nmol/l based on the 97th percentile of Americans post-fortification (NHANES)). Determinants of these high concentrations are poorly understood, though an association has been posited between high intakes of folic acid and adverse health outcomes. This research investigated determinants of high folate concentrations in Canadians.

Methods RBC folate concentrations from the nationally representative Canadian Health Measures Survey were examined in participants aged 6–79 years (N=5248). The population was described using frequencies and percentages. Sociodemographic, behavioural and clinical determinants of high RBC folate concentrations were examined using univariate and separate multiple logistic regression models controlling for age and household income.

Results The greatest proportion of high concentrations occurred in females (42.5%), higher age groups (6–11 years (36.4%), 12–19 years (25.6%), 20–39 years (32.9%), 40–59 years (44.5%), 60–79 years (53.6%)) and higher income quartiles (33.5% (Q1), 37.6% (Q2), 41.6% (Q3), 46.6% (Q4)). Folic acid containing supplement users had a greater prevalence of high concentrations (62.8%) than non-users (37.2%). Prevalence of high concentrations climbed with increasing intake of fruit/vegetables (>3 times per day (46.8%)) and grain products (>3 times per day (45.5%)). Never smokers (39.5%) and former smokers (49.1%) had a greater prevalence of high concentrations than daily smokers (28.4%). Detailed regression results will be presented at the conference.

Conclusion Determinants of high folate concentrations should be considered when refining folic acid supplementation and fortification policies. Future research on the relationship between high folate concentrations and health outcomes is warranted.