title: Validity and reproducibility of a food frequency questionnaire for assessment of fruit and vegetable intake in Iranian adults(*).
abstract: BACKGROUND
  This study's aim was to design and validate a semi-quantitative food frequency questionnaire (FFQ) for assessment of fruits and vegetables (FV) consumption in adults of Isfahan by comparing the FFQ with dietary reference method and blood plasma levels of beta-carotene, vitamin C, and retinol.
  
  
  METHODS
  This validation study was performed on 123 healthy adults of Isfahan. FV intake was assessed using a 110-item FFQ. Data collection was performed during two different time periods to control for seasonal effects, fall/winter (cold season) and spring/summer (warm season). In each phase a FFQ and 1 day recall, and 2 days of food records as the dietary reference method were completed and plasma vitamin C, beta-carotene and retinol were measured. Data was analyzed by Pearson or Spearman and intraclass correlations.
  
  
  RESULTS
  Serum Lipids, sex, age, body mass index (BMI) and educational level adjusted Pearson correlation coefficient of FV with plasma vitamin C, beta-carotene and retinol were 0.55, 0.47 and 0.28 in the cold season (p < 0.05) and 0.52, 0.45 and 0.35 in the warm season (p < 0.001), respectively. Energy and fat intake, sex, age, BMI and educational level adjusted Pearson correlation coefficient for FV with dietary reference method in the cold and warm seasons were 0.62 and 0.60, respectively (p < 0.001). Intraclass correlation for reproducibility of FFQ in FV was 0.65 (p<0.001).
  
  
  CONCLUSIONS
  The designed FFQ had a good criterion validity and reproducibility for assessment of FV intake. Thus, it can serve as a valid tool in epidemiological studies to assess fruit and vegetable intake.
authors.affiliation: MSc in Nutrition, Department of Nutrition, Isfahan Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Noushin
authors.initials: N
authors.lastname: Mohammadifard
authors.forename: Nasrin
authors.initials: N
authors.lastname: Omidvar
authors.forename: Anahita
authors.initials: A
authors.lastname: Houshiarrad
authors.forename: Tirang
authors.initials: T
authors.lastname: Neyestani
authors.forename: Gholam-Ali
authors.initials: GA
authors.lastname: Naderi
authors.forename: Bahram
authors.initials: B
authors.lastname: Soleymani