title: Prevalence and correlates of high red blood cell folate concentrations in the Canadian population using 3 proposed cut-offs.
abstract: A distinct shift towards higher folate concentrations has emerged in Canada. These higher concentrations have known benefits, including prevention of neural tube defects, but concerns have been raised regarding potential associations with adverse health outcomes. The aim of this research was to propose cut-offs for high red blood cell (RBC) folate concentrations and identify their correlates. RBC folate was measured in a nationally representative cross-sectional sample of Canadians (N = 5248) aged 6 to 79 years. RBC folate concentrations were adjusted from the IMMULITE 2000 immunoassay to a microbiologic assay. The population was characterized at 3 RBC folate cut-offs: 1450 nmol/L, 1800 nmol/L, and 2150 nmol/L. We used t tests to examine differences by age, sex, income, and body mass index (BMI) at each cut-off and logistic regression to explore associations with folic acid supplement intake. The prevalence of high RBC folate was 16%, 6%, and 2% at thresholds of 1450 nmol/L, 1800 nmol/L, and 2150 nmol/L, respectively. Females, those aged 60 to 79 years, and overweight or obese participants had the greatest prevalence of having high RBC folate at each cut-off. Folic acid supplement users were more likely than non-users to have high RBC folate concentrations. Older age, higher BMI, and folic acid supplement use were identified as correlates of high folate status. A high RBC folate concentration cut-off will advance the field towards consistent measurement and reporting of high folate status. This may facilitate future investigation of associations between RBC folate concentrations at the upper end of the distribution and health outcomes.
authors: a Institute of Population Health, University of Ottawa, Ottawa, ON K1N 6N5, Canada.|b Healthy Active Living and Obesity Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada.
authors: Cynthia K
authors: CK
authors: Colapinto
authors: c Department of Nutritional Sciences, University of Toronto, Toronto, ON M5S 3E2, Canada.|d Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
authors: Deborah L
authors: DL
authors: O'Connor
authors: a Institute of Population Health, University of Ottawa, Ottawa, ON K1N 6N5, Canada.|e School of Epidemiology, Public Health and Preventive Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
authors: Lise
authors: L
authors: Dubois
authors: b Healthy Active Living and Obesity Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada.|f Department of Pediatrics, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, ON K1H 8L1, Canada.
authors: Mark S
authors: MS
authors: Tremblay
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D002170:Canada; D002648:Child; D003430:Cross-Sectional Studies; D019587:Dietary Supplements / Q000706:statistics & numerical data; D004912:Erythrocytes; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys / Q000706:statistics & numerical data*; D015995:Prevalence; D064167:Recommended Dietary Allowances; D055815:Young Adult
chemical_list: D005492:Folic Acid
keywords: CHMS; Canadian Health Measures Survey; ECMS; Enquête canadienne sur les mesures de la santé; RBC folate; acide folique; folate; folate élevé; folate érythrocytaire; folic acid; high folate; red blood cell folate