title: Validity and reliability of a self-administered food frequency questionnaire for the JPHC study: The assessment of amino acid intake.
abstract: BACKGROUND
  The Japanese database of food amino acid composition was revised in 2010 after a 24-year interval. To examine the impact of the 2010 revision compared with that of the 1986 revision, we evaluated the validity and reliability of amino acid intakes assessed using a food frequency questionnaire (FFQ).
  
  
  METHODS
  A FFQ including 138 food items was compared with 7-day dietary records, completed during each distinct season, to assess validity and administered twice at approximately a 1-year interval, to assess reliability. We calculated amino acid intakes using a database that compensated for missing food items via the substitution method. Subjects were a subsample of two cohorts of the Japan Public Health Center-based prospective study. A total of 102 men and 113 women in Cohort I and 174 men and 176 women in Cohort II provided complete dietary records and the FFQ, of whom 101 men and 108 women of Cohort I and 143 men and 146 women of Cohort II completed the FFQ twice.
  
  
  RESULTS
  In the comparison of the FFQ with dietary records, the medians (ranges) of energy-adjusted correlation coefficients for validity were 0.35 (0.25-0.43) among men and 0.29 (0.19-0.40) among women in Cohort I, and 0.37 (0.21-0.52) and 0.38 (0.24-0.59), respectively, in Cohort II. Values for reliability were 0.47 (0.42-0.52) among men and 0.43 (0.38-0.50) among women in Cohort I, and 0.59 (0.52-0.70) and 0.54 (0.45-0.61), respectively, in Cohort II.
  
  
  CONCLUSIONS
  The FFQ used in our prospective cohort study is a suitable tool for estimating amino acid intakes.
authors.affiliation: Public Health, Department of Social Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Okada
authors.affiliation: Public Health, Department of Social Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan. Electronic address: iso@pbhel.med.osaka-u.ac.jp.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iso
authors.affiliation: Graduate School of Nutritional Sciences, Sagami Women's University, Sagamihara, Kanagawa, Japan; Epidemiology and Prevention Group, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Ishihara
authors.affiliation: Department of Public Health, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Koutatsu
authors.initials: K
authors.lastname: Maruyama
authors.affiliation: Epidemiology and Prevention Group, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
authors.forename: Norie
authors.initials: N
authors.lastname: Sawada
authors.affiliation: Epidemiology and Prevention Group, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage*; D015930:Diet Records; D004034:Diet Surveys; D002149:Energy Intake; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012737:Sex Factors; D011795:Surveys and Questionnaires
chemical_list: D000596:Amino Acids
keywords: Amino acid intake; Diet; Food frequency questionnaire; Reliability; Validity