title: Validity of a food frequency questionnaire varied by age and body mass index.
abstract: OBJECTIVE
  The validity of food frequency questionnaires (FFQs) in measuring food consumption and nutrient intake has to be assessed. The objective of this study was to assess the validity of a 128-item FFQ in specific subgroups of Finnish adults.
  
  
  METHODS
  The study included 294 subjects (137 men and 157 women). A 3-day food record was used as the reference method.
  
  
  RESULTS
  The mean intake of all nutrients except alcohol was higher measured with the FFQ than with the food records. In general, the Pearson correlations for energy adjusted nutrients between the FFQ and the food records were higher in women than in men. The correlations ranged from 0.14 (retinol) to 0.66 (fiber and alcohol) in men, and from 0.20 (long-chain n-3 fatty acids) to 0.70 (alcohol) in women. The results in subgroups showed that measuring nutrient intakes is more difficult among younger (30-50 years) women and overweight men and women than among others.
  
  
  CONCLUSIONS
  The study showed that the FFQ is a useful tool in epidemiologic studies in measuring the diet of Finnish adults given that the problems among specific subgroups are taken into account in interpretation.
authors.affiliation: Department of Health Promotion and Chronic Disease Prevention, National Public Health Institute, Helsinki, Finland. laura.paalanen@ktl.fi
authors.forename: Laura
authors.initials: L
authors.lastname: Paalanen
authors.forename: Satu
authors.initials: S
authors.lastname: Männistö
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Virtanen
authors.forename: Paul
authors.initials: P
authors.lastname: Knekt
authors.forename: Leena
authors.initials: L
authors.lastname: Räsänen
authors.forename: Jukka
authors.initials: J
authors.lastname: Montonen
authors.forename: Pirjo
authors.initials: P
authors.lastname: Pietinen
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D015992:Body Mass Index; D004032:Diet; D015930:Diet Records; D004034:Diet Surveys; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D011795:Surveys and Questionnaires