title: [Seasonal variation of food intake in food frequency questionnaire among workers in a nuclear power plant].
abstract: OBJECTIVE
  This study was conducted to investigate the systematic error, such as seasonal change or inadequate food items, in a food frequency questionnaire administered to workers in a Nuclear Power Plant, Korea.
  
  
  METHODS
  We performed three repeat-tests with 28 subjects on May 13, July 8 and Dec 16, 1992. Our food frequency questionnaire (FFQ) comprised 84 foods organized into 7 food-groups, and was composed of the items of usual intake frequency (8 categories) and the amount per intake (3 or 4 categories) over the previous year. We compared the means of intake frequency and the frequency of the portion-size according to each season using Repeated Measures ANOVA and Pearson's chi-square test with Fisher's exact test.
  
  
  RESULTS
  We found the significant seasonal changes of several food items in intake frequency measurement. These items were typical seasonal foods such as mandarin orange, plum and green vegetables, while the single questions consisted of inadequate food items such as thick beef or similar soup and various kimchi products. Significant seasonal changes in portion-size were found in only two items: cooked rice-brown and fresh/frozen fishes.
  
  
  CONCLUSIONS
  The systematic errors observed could caused loss of validity in the FFQ. Consideration should be given for seasonal variation in FFQ survey and methodological concerns are needed to improve the quality for measuring usual diet pattern.
authors.affiliation: School of Public Health, Seoul National University, Korea.
authors.forename: Jae Jeong
authors.initials: JJ
authors.lastname: Yang
authors.forename: Sue Kyung
authors.initials: SK
authors.lastname: Park
authors.forename: Hyun-Sul
authors.initials: HS
authors.lastname: Lim
authors.forename: Kwang-Pil
authors.initials: KP
authors.lastname: Ko
authors.forename: Younjhin
authors.initials: Y
authors.lastname: Ahn
authors.forename: Yoon Ok
authors.initials: YO
authors.lastname: Ahn
mesh_terms: D004034:Diet Surveys; D006801:Humans; D007723:Korea; D011210:Power Plants; D015203:Reproducibility of Results; D012621:Seasons; D011795:Surveys and Questionnaires