title: Validity and reliability of a new food frequency questionnaire compared to 24 h recalls and biochemical measurements: pilot phase of Golestan cohort study of esophageal cancer.
abstract: BACKGROUND
  A pilot study was carried out to evaluate validity and reproducibility of a food frequency questionnaire (FFQ), which was designed to be used in a prospective cohort study in a population at high risk for esophageal cancer in northern Iran.
  
  
  METHODS
  The FFQ was administered four times to 131 subjects, aged 35-65 years, of both sexes. Twelve 24-h dietary recalls for two consecutive days were administered monthly during 1 year and used as a reference method. The excretion of nitrogen was measured on four 24-h urine samples, and plasma levels of beta-carotene, retinol, vitamin C and alpha-tocopherol was measured from two time points. Relative validity of FFQ and 24-h diet recall was assessed by comparing nutrient intake derived from both methods with the urinary nitrogen and plasma levels of beta-carotene, retinol, vitamin C and alpha-tocopherol.
  
  
  RESULTS
  Correlation coefficients comparing energy and nutrients intake based on the mean of the four FFQ and the mean of twelve 24-h diet recalls were 0.75 for total energy, 0.75 for carbohydrates, 0.76 for proteins and 0.65 for fat. Correlation coefficients between the FFQ-based intake and serum levels of beta-carotene, retinol, vitamin C and vitamin E/alpha-tocopherol were 0.37, 0.32, 0.35 and 0.06, respectively. Correlation coefficients between urinary nitrogen and FFQ-based protein intake ranged from 0.23 to 0.35. Intraclass correlation coefficients used to measure reproducibility of FFQ ranged from 0.66 to 0.89.
  
  
  CONCLUSIONS
  We found that the FFQ provides valid and reliable measurements of habitual intake for energy and most of the nutrients studied.
authors.affiliation: Digestive Disease Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: A F
authors.initials: AF
authors.lastname: Malekshah
authors.forename: M
authors.initials: M
authors.lastname: Kimiagar
authors.forename: M
authors.initials: M
authors.lastname: Saadatian-Elahi
authors.forename: A
authors.initials: A
authors.lastname: Pourshams
authors.forename: M
authors.initials: M
authors.lastname: Nouraie
authors.forename: G
authors.initials: G
authors.lastname: Goglani
authors.forename: A
authors.initials: A
authors.lastname: Hoshiarrad
authors.forename: M
authors.initials: M
authors.lastname: Sadatsafavi
authors.forename: B
authors.initials: B
authors.lastname: Golestan
authors.forename: A
authors.initials: A
authors.lastname: Yoonesi
authors.forename: N
authors.initials: N
authors.lastname: Rakhshani
authors.forename: S
authors.initials: S
authors.lastname: Fahimi
authors.forename: D
authors.initials: D
authors.lastname: Nasrollahzadeh
authors.forename: R
authors.initials: R
authors.lastname: Salahi
authors.forename: A
authors.initials: A
authors.lastname: Ghafarpour
authors.forename: S
authors.initials: S
authors.lastname: Semnani
authors.forename: J P
authors.initials: JP
authors.lastname: Steghens
authors.forename: C C
authors.initials: CC
authors.lastname: Abnet
authors.forename: F
authors.initials: F
authors.lastname: Kamangar
authors.forename: S M
authors.initials: SM
authors.lastname: Dawsey
authors.forename: P
authors.initials: P
authors.lastname: Brennan
authors.forename: P
authors.initials: P
authors.lastname: Boffetta
authors.forename: R
authors.initials: R
authors.lastname: Malekzadeh
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004032:Diet; D004034:Diet Surveys; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake / Q000502:physiology; D004938:Esophageal Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000652:urine; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D009584:Nitrogen / Q000652:urine*; D010865:Pilot Projects; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires / Q000592:standards*; D014815:Vitamins / Q000097:blood*
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D014815:Vitamins; D009584:Nitrogen