title: A review of food frequency questionnaires developed and validated in Japan.
abstract: BACKGROUND
  The food frequency questionnaire (FFQ) has been used throughout the world for epidemiological purposes. Because dietary habits vary greatly, the FFQ must be tailored for use with specific populations. The usefulness of FFQs in Japan was assessed by reviewing questionnaires developed and validated in that country.
  
  
  METHODS
  A literature search was conducted to identify articles on the development and/or validation of FFQs for Japanese populations. For each FFQ identified, validation studies were used to abstract its characteristics and information. The correlation coefficients between diet records (DRs) and FFQ estimates and those between the same FFQs completed twice were used to evaluate validity and reproducibility, respectively, of the questionnaires.
  
  
  RESULTS
  Twenty-one eligible FFQs were identified. They were found to be reasonably valid and reproducible. The median of correlation coefficients between DRs and FFQs ranged from 0.31 to 0.56 for target nutrients, and that between the same FFQs completed twice within a period of 9 months to 1 year ranged from 0.50 to 0.72. Relatively poor validity was found for FFQ estimates on consumption of potatoes, seaweed, sodium, niacin, and polyunsaturated fatty acids. For the purpose of analysis, FFQs were divided into long FFQs (97 or more food items) and short FFQs (<70 items); the former had slightly higher validity.
  
  
  CONCLUSIONS
  FFQs are useful for assessing dietary intake in Japan, although careful consideration is required for the food groups and nutrients for which FFQs had low validity.
authors.affiliation: Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Japan. wakai@med.nagoya-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
mesh_terms: D015930:Diet Records; D004034:Diet Surveys; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D019317:Evidence-Based Medicine; D005247:Feeding Behavior; D005502:Food; D006801:Humans; D007564:Japan / Q000453:epidemiology; D015596:Nutrition Assessment; D009753:Nutritive Value; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*; D014675:Vegetables
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins