title: Determinants of folate and vitamin B12 plasma levels in the French E3N-EPIC cohort.
abstract: OBJECTIVE
  Impaired B vitamin status has been identified as a risk factor for major chronic diseases. This study aims at examining the determinants of plasma folate and vitamin B12 concentrations, considering lifestyle factors and MTHFR polymorphisms.
  
  
  METHODS
  A total of 988 women aged 40-65 years from the French E3N cohort were investigated. Intakes of folate and vitamin B12 were assessed using food frequency questionnaires, and plasma concentrations were measured by microbiological assay. Dietary scores were computed to summarize folate and vitamin B12 dietary sources. MTHFR-C677T and MTHFR-A1298C were determined by Kaspar assay. Pearson's partial correlation coefficients and multivariable linear regression models were used to assess correlations between main determinants and plasma folate and vitamin B12 levels.
  
  
  RESULTS
  The partial correlation coefficient between dietary intakes and plasma folate was 0.19 (p value <0.001) and 0.08 (p value = 0.008) for vitamin B12. Dietary scores were the main determinant of B vitamin plasma concentrations with a percent change per unit increase of 12.64% (p value <0.001) for folate and 7.6% (p value <0.001) for vitamin B12. Homozygous (T/T) or heterozygous (C/T) women for MTHFR-C677T had lower plasma folate concentrations [C/T: -6.48% (p value = 0.038) and T/T: -15.89% (p value <0.001)] compared to women carrying the C/C genotype. Other determinants of B vitamin plasma concentration include: smoking status for folate, and age and hormone replacement therapy for vitamin B12.
  
  
  CONCLUSIONS
  We confirmed previous findings on the role of diet as main determinant of folate and vitamin B12 plasma concentrations. However, the impact of genetic polymorphisms and lifestyle factors on plasma B vitamin concentrations should not be neglected.
authors.affiliation: International Agency for Research on Cancer (IARC), 150 cours Albert Thomas, 69008, Lyon, France. jordidebatlle@gmail.com.
authors.forename: Jordi
authors.identifier: http://orcid.org/0000-0003-3500-6608
authors.initials: J
authors.lastname: de Batlle
authors.affiliation: International Agency for Research on Cancer (IARC), 150 cours Albert Thomas, 69008, Lyon, France.
authors.forename: Marco
authors.initials: M
authors.lastname: Matejcic
authors.affiliation: International Agency for Research on Cancer (IARC), 150 cours Albert Thomas, 69008, Lyon, France.
authors.forename: Veronique
authors.initials: V
authors.lastname: Chajes
authors.affiliation: Universidad Autónoma Metropolitana, Mexico City, Mexico.
authors.forename: Hortensia
authors.initials: H
authors.lastname: Moreno-Macias
authors.affiliation: International Agency for Research on Cancer (IARC), 150 cours Albert Thomas, 69008, Lyon, France.
authors.forename: Amina
authors.initials: A
authors.lastname: Amadou
authors.affiliation: International Agency for Research on Cancer (IARC), 150 cours Albert Thomas, 69008, Lyon, France.
authors.forename: Nadia
authors.initials: N
authors.lastname: Slimani
authors.affiliation: INSERM U1052, Cancer Research Center of Lyon, Centre Léon Bérard, Lyon, France.
authors.forename: David G
authors.initials: DG
authors.lastname: Cox
authors.affiliation: Team 9: Lifestyle, Genes and Health: Integrative Trans-generational Epidemiology, Center for Research in Epidemiology and Population Health, Institut National de la Santé et de la Recherche Médicale (INSERM), U1018, Villejuif, France.|Université Paris-Sud, Villejuif, France.|Gustave Roussy Institute, Villejuif, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Clavel-Chapelon
authors.affiliation: Team 9: Lifestyle, Genes and Health: Integrative Trans-generational Epidemiology, Center for Research in Epidemiology and Population Health, Institut National de la Santé et de la Recherche Médicale (INSERM), U1018, Villejuif, France.|Université Paris-Sud, Villejuif, France.|Gustave Roussy Institute, Villejuif, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Fagherazzi
authors.affiliation: International Agency for Research on Cancer (IARC), 150 cours Albert Thomas, 69008, Lyon, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Romieu
mesh_terms: D019943:Amino Acid Substitution; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D015331:Cohort Studies; D004032:Diet / Q000009:adverse effects*; D000072001:Diet, Healthy; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005494:Folic Acid Deficiency / Q000097:blood / Q000209:etiology* / Q000235:genetics / Q000517:prevention & control; D005602:France / Q000453:epidemiology; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D008875:Middle Aged; D009752:Nutritional Status; D010349:Patient Compliance; D020641:Polymorphism, Single Nucleotide; D011446:Prospective Studies; D057566:Self Report; D014805:Vitamin B 12 / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000209:etiology* / Q000235:genetics / Q000517:prevention & control
chemical_list: D015415:Biomarkers; D005492:Folic Acid; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12
keywords: Biomarkers; Dietary intake; Folate; MTHFR polymorphisms; Vitamin B12