title: Validity of a questionnaire to assess fruit and vegetable intake in adults.
abstract: OBJECTIVE
  To validate a method for assessing fruit and vegetable intake among adults in a population of low intake. The method assesses mean intake and ranks individuals by their usual intake.
  
  
  METHODS
  A precoded fruit and vegetable Questionnaire included a 24-h recall and a food frequency. The participants filled in the Questionnaire, a week later they started a 7-day food record, 1-day weighed record and 6 days using household measures.
  
  
  METHODS
  Following advertisements 40 participants were recruited, 36 returned food records(mean age=37 years).
  
  
  RESULTS
  No difference was observed between the average intake yielded by the 24-h recall and that from the 1-day weighed food record of fruits or vegetables. Correlation coefficients between results from the food frequency questionnaire and the 7-day food records were 0.45 (P=0.007) for vegetables, 0.63 (P<0.001) for fruits and 0.73 (P<0.001) for fruits and vegetables combined. Cross-classification into quartiles showed that the proportion of participants in the same or the adjacent quartile of the intake distribution were 94% for fruit intake and 80% for vegetable intake. Registered intake of fruits and vegetables was higher the first 4 days of the record than the last 3 days (P=0.002). The 4-day food record correlated with the food frequency questionnaire in similar manner as the 7-day record.
  
  
  CONCLUSIONS
  The present study indicates that the precoded 24-h recall may be valuable tool for measuring average intake of fruits and vegetables among adults in a population of low intake. Moreover, the food frequency questionnaire was valid for ranking individuals according to their usual intake. A 4-day food record might be sufficient when validating food frequency questionnaires for fruits and vegetables.
authors.affiliation: Unit for Nutrition Research, Landspitali-University Hospital & Department of Food Science, University of Iceland, Reykjavik, Iceland.
authors.forename: A G
authors.initials: AG
authors.lastname: Kristjansdottir
authors.forename: L F
authors.initials: LF
authors.lastname: Andersen
authors.forename: J
authors.initials: J
authors.lastname: Haraldsdottir
authors.forename: M D V
authors.initials: MD
authors.lastname: de Almeida
authors.forename: I
authors.initials: I
authors.lastname: Thorsdottir
mesh_terms: D000328:Adult; D015930:Diet Records; D004034:Diet Surveys; D005260:Female; D005638:Fruit; D006801:Humans; D007055:Iceland; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D015203:Reproducibility of Results; D012650:Self Disclosure; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires / Q000592:standards*; D014675:Vegetables