title: Validity of food frequency questionnaire-based estimates of long-term long-chain n-3 polyunsaturated fatty acid intake.
abstract: OBJECTIVE
  To evaluate how long-term dietary intake of long-chain n-3 polyunsaturated fatty acids (LCn-3 PUFAs), estimated by repeated food frequency questionnaires (FFQs) over 15 years, is correlated with LCn-3 PUFAs in adipose tissue (AT).
  
  
  METHODS
  Subcutaneous adipose tissue was obtained in 2003-2004 (AT-03) from 239 randomly selected women, aged 55-75 years, after completion of a 96-item FFQ (FFQ-03). All participants had previously returned an identical FFQ in 1997 (FFQ-97) and a 67-item version in 1987-1990 (FFQ-87). Pearson product-moment correlations were used to evaluate associations between intake of total and individual LCn-3 PUFAs as estimated by the three FFQ assessments and AT-03 content (% of total fatty acids).
  
  
  RESULTS
  FFQ-estimated mean relative intake of LCn-3 PUFAs (% of total fat intake) increased between all three assessments (FFQ-87, 0.55 ± 0.34; FFQ-97, 0.74 ± 0.64; FFQ-03, 0.88 ± 0.56). Validity, in terms of Pearson correlations between FFQ-03 estimates and AT-03 content, was 0.41 (95% CI 0.30-0.51) for total LCn-3 PUFA and ranged from 0.29 to 0.48 for individual fatty acids; lower correlation was observed among participants with higher percentage body fat. With regard to long-term intake estimates, past dietary intake was also correlated with AT-03 content, with correlation coefficients in the range of 0.21-0.33 and 0.21-0.34 for FFQ-97 and FFQ-87, respectively. The correlations were improved by using average estimates from two or more FFQ assessments. Exclusion of fish oil supplement users (14%) did not alter the correlations.
  
  
  CONCLUSIONS
  These data indicate reasonable validity of FFQ-based estimates of long-term (up to 15 years) LCn-3 PUFA intake, justifying their use in studies of diet-disease associations.
authors.affiliation: Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, 171 77, Stockholm, Sweden.
authors.forename: Alice
authors.initials: A
authors.lastname: Wallin
authors.forename: Daniela
authors.initials: D
authors.lastname: Di Giuseppe
authors.forename: Ann
authors.initials: A
authors.lastname: Burgaz
authors.forename: Niclas
authors.initials: N
authors.lastname: Håkansson
authors.forename: Tommy
authors.initials: T
authors.lastname: Cederholm
authors.forename: Karl
authors.initials: K
authors.lastname: Michaëlsson
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000818:Animals; D001823:Body Composition; D018797:Cell Cycle Proteins; D004032:Diet; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage* / Q000032:analysis; D005260:Female; D005399:Fishes; D005502:Food; D006801:Humans; D008460:Meat; D008875:Middle Aged; D011200:Poultry; D011505:Protein-Tyrosine Kinases; D015203:Reproducibility of Results; D029701:Saccharomyces cerevisiae Proteins; D017747:Seafood; D050151:Subcutaneous Fat / Q000737:chemistry; D011795:Surveys and Questionnaires
chemical_list: D018797:Cell Cycle Proteins; D015525:Fatty Acids, Omega-3; D029701:Saccharomyces cerevisiae Proteins; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases