title: Separate estimates of portion size were not essential for energy and nutrient estimation: results from the Southern Community Cohort food-frequency questionnaire pilot study.
abstract: OBJECTIVE
  A food-frequency questionnaire (FFQ) was developed to assess habitual dietary intake in the Southern Community Cohort Study (SCCS), a prospective epidemiological study to analyse disparities in cancer and other chronic diseases between African-Americans and Whites.
  
  
  METHODS
  Frequency and portion size estimates were obtained for each of 104 foods. Daily intakes of 13 food groups, energy and 18 nutrients were computed. Each participant's rank and quintile classification of nutrient intakes was determined with and without the use of the subject's reported portion size.
  
  
  METHODS
  The sample was obtained from the SCCS pilot study conducted in Tennessee, Mississippi and Florida, and consisted of 209 adults, 54% African-American, with a mean (standard deviation) age of 57.1 (12.5) years.
  
  
  RESULTS
  Correlations between the ranks from the two methods of estimation were high, ranging from 0.66 to 0.94 for food groups and 0.81 to 0.94 for nutrients. Pearson correlations were similarly high for food groups and nutrients. Concordance in exact quintile rank across the nutrient indices ranged from 52 to 70%, rising to 90-99% for concordance within adjacent quintiles.
  
  
  CONCLUSIONS
  To reduce the respondents' burden and to increase data completeness, the assignment of a uniform portion size when scoring the SCCS FFQ was considered acceptable.
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, TN 37232, USA. david.schlundt@vanderbilt.edu
authors.forename: David G
authors.initials: DG
authors.lastname: Schlundt
authors.forename: Maciej S
authors.initials: MS
authors.lastname: Buchowski
authors.forename: Margaret K
authors.initials: MK
authors.lastname: Hargreaves
authors.forename: Jean H
authors.initials: JH
authors.lastname: Hankin
authors.forename: Lisa B
authors.initials: LB
authors.lastname: Signorello
authors.forename: William J
authors.initials: WJ
authors.lastname: Blot
mesh_terms: D001741:Black or African American / Q000523:psychology / Q000706:statistics & numerical data; D015331:Cohort Studies; D002149:Energy Intake / Q000502:physiology*; D005260:Female; D005502:Food / Q000145:classification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D012858:Size Perception; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D044465:White People / Q000523:psychology / Q000706:statistics & numerical data