title: Using exploratory factor analysis of FFQ data to identify dietary patterns among Yup'ik people.
abstract: OBJECTIVE
  An FFQ developed by the Center for Alaska Native Health Research for studies in Yup'ik people includes market foods and subsistence foods such as moose, seal, waterfowl and salmon that may be related to disease risk. Because the FFQ contains >100 food items, we sought to characterize dietary patterns more simply for use in ongoing pharmacogenomics studies.
  
  
  METHODS
  Exploratory factor analysis was used to derive a small number of 'factors' that explain a substantial amount of the variation in the Yup'ik diet. We estimated factor scores and measured associations with demographic characteristics and biomarkers.
  
  
  METHODS
  South-west Alaska, USA.
  
  
  METHODS
  Yup'ik people (n 358) aged ≥18 years.
  
  
  RESULTS
  We identified three factors that each accounted for ≥10 % of the common variance: the first characterized by 'processed foods' (e.g. salty snacks, sweetened cereals); the second by 'fruits and vegetables' (e.g. fresh citrus, potato salad); and the third by 'subsistence foods' (seal or walrus soup, non-oily fish). Participants from coastal communities had higher values for the 'subsistence' factor, whereas participants from inland communities had higher values for the 'fruits and vegetables' factor. A biomarker of marine intake, δ 15N, was correlated with the 'subsistence' factor, whereas a biomarker of corn- and sugarcane-based market food intake, δ 13C, was correlated with 'processed foods'.
  
  
  CONCLUSIONS
  The exploratory factor analysis identified three factors that appeared to reflect dietary patterns among Yup'ik based on associations with participant characteristics and biomarkers. These factors will be useful for chronic disease studies in this population.
authors.affiliation: 1 Department of Epidemiology, School of Public Health, University of Washington, Box 357236, Seattle, WA 98195, USA.
authors.forename: Tove K
authors.initials: TK
authors.lastname: Ryman
authors.affiliation: 1 Department of Epidemiology, School of Public Health, University of Washington, Box 357236, Seattle, WA 98195, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Austin
authors.affiliation: 2 Center for Alaska Native Health Research, Irving I, University of Alaska Fairbanks, Fairbanks, AK, USA.
authors.forename: Scarlett
authors.initials: S
authors.lastname: Hopkins
authors.affiliation: 2 Center for Alaska Native Health Research, Irving I, University of Alaska Fairbanks, Fairbanks, AK, USA.
authors.forename: Jacques
authors.initials: J
authors.lastname: Philip
authors.affiliation: 2 Center for Alaska Native Health Research, Irving I, University of Alaska Fairbanks, Fairbanks, AK, USA.
authors.forename: Diane
authors.initials: D
authors.lastname: O'Brien
authors.affiliation: 3 Department of Pharmaceutics, University of Washington, Seattle, WA, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Thummel
authors.affiliation: 2 Center for Alaska Native Health Research, Irving I, University of Alaska Fairbanks, Fairbanks, AK, USA.
authors.forename: Bert B
authors.initials: BB
authors.lastname: Boyer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000413:Alaska / Q000208:ethnology; D015415:Biomarkers; D002247:Carbon Isotopes / Q000032:analysis / Q000097:blood; D003466:Cultural Characteristics; D004032:Diet / Q000208:ethnology* / Q000523:psychology / Q000706:statistics & numerical data; D002149:Energy Intake; D005163:Factor Analysis, Statistical; D005260:Female; D005518:Food Preferences / Q000523:psychology; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009587:Nitrogen Isotopes / Q000032:analysis / Q000097:blood; D015596:Nutrition Assessment; D044382:Population Groups / Q000523:psychology*; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires / Q000592:standards; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes