title: Development, validity, and reliability of a food frequency questionnaire for antioxidants in elderly Iranian people.
abstract: BACKGROUND
  The food frequency questionnaire (FFQ), as a way to assess the dietary intake in comparison with other methods, is easier to analyze and takes less time and is less costly. Our aim in this study was to develop and validate an FFQ for estimating the intakes of selected antioxidants in elderly Iranian people.
  
  
  METHODS
  A total of 185 elderly people were randomly selected. Three-day food records were completed by the subjects and collected every 2 months and dietary intake levels of zinc, selenium, carotenes and vitamins C and E were estimated. Based on the food records data, geographic location, and age, an FFQ was designed to estimate antioxidant intakes during 1 year. In addition, for controlling energy intake, 2-day food records were also collected with the food frequency questionnaire. To assess the reliability, 40 individuals were asked to complete the FFQ twice with an interval of 3 months in between.
  
  
  RESULTS
  Intraclass correlation coefficient (ICC) between the two FFQs for antioxidant C, antioxidant E, carotene, selenium, and zinc were 0.62, 0.47, 0.51, 0.54, and 0.58, respectively (P< 0.05). In addition, Pearson correlation coefficients between the FFQ and the food records, after controlling energy for vitamin C, vitamin E, carotene, selenium, and zinc, were 0.46, 0.48, 0.38, 0.55, and 0.47 respectively (P< 0.001).
  
  
  CONCLUSIONS
  According to the results of this study, considering the fact that the FFQ was designed for the elderly and the special conditions (patience, memory, etc.) and vulnerability of this age group, the questionnaire is relatively valid and reliable to use.
authors.affiliation: Department of Community Nutrition, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Malekahmadi
authors.affiliation: Department of Community Nutrition, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Amirmansour Alavi
authors.initials: AA
authors.lastname: Naeini
authors.affiliation: Department of Community Nutrition, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Sakineh
authors.initials: S
authors.lastname: Shab-Bidar
authors.affiliation: Department of Health Sciences, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Awat
authors.initials: A
authors.lastname: Feizi
authors.affiliation: Department of Community Nutrition, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abolghasem
authors.initials: A
authors.lastname: Djazayery
keywords: Antioxidants; elderly; food frequency questionnaire (FFQ); reliability; validity