title: Associations between dietary methods and biomarkers, and between fruits and vegetables and risk of ischaemic heart disease, in the EPIC Norfolk Cohort Study.
abstract: BACKGROUND
  Methods for assessing diet are prone to measurement error, which may be substantial in large cohort investigations. Biomarkers can be used as objective measures with which to compare estimates of nutritional exposure using different methods
  
  
  METHODS
  Cross sectional comparisons in 12 474 men and women of regression between biomarkers for vitamin C, sodium, potassium, fibre, carbohydrate, fat and phytoestrogens with intakes derived from food diaries and food frequency questionnaires (FFQ), and odds ratios for risk of ischaemic heart disease (IHD) by dietary and plasma vitamin C.
  
  
  RESULTS
  There were strong (P < 0.001) associations between biomarkers and intakes as assessed by food diary. Coefficients were markedly attenuated for data obtained from the FFQ, especially so for vitamin C, potassium and phytoestrogens (Z P < 0.05). Risk of IHD was associated with plasma vitamin C (P < 0.001) and intake of vitamin C and fruit and vegetables assessed by food diary (P quintile trends <0.001, 0.001) but not by the FFQ (P quintile trends 0.923, 0.186).
  
  
  CONCLUSIONS
  Nutritional data that reflect the findings from biomarkers reduce measurement error and will thus improve statistical power in studies of gene nutrient interactions in cohort studies.
authors.affiliation: Medical Research Council, Dunn Human Nutrition Unit, Welcome Trust/MRC Building, Cambridge, UK. sab@mrc-dunn.cam.ac.uk
authors.forename: Sheila
authors.initials: S
authors.lastname: Bingham
authors.forename: Robert
authors.initials: R
authors.lastname: Luben
authors.forename: Ailsa
authors.initials: A
authors.lastname: Welch
authors.forename: Yen Ling
authors.initials: YL
authors.lastname: Low
authors.forename: Kay Tee
authors.initials: KT
authors.lastname: Khaw
authors.forename: Nick
authors.initials: N
authors.lastname: Wareham
authors.forename: Nick
authors.initials: N
authors.lastname: Day
mesh_terms: D000368:Aged; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood; D015415:Biomarkers / Q000097:blood; D002338:Carotenoids / Q000097:blood; D015331:Cohort Studies; D004032:Diet; D015930:Diet Records; D004034:Diet Surveys; D004739:England; D005260:Female; D005638:Fruit; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000097:blood / Q000209:etiology*; D011795:Surveys and Questionnaires; D014675:Vegetables; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood
chemical_list: D015415:Biomarkers; D014815:Vitamins; D002338:Carotenoids; D001205:Ascorbic Acid