title: Cruciferous vegetable intake questionnaire improves cruciferous vegetable intake estimates.
abstract: OBJECTIVE
  To develop a validated, focused Cruciferous Vegetable Food Frequency Questionnaire (FFQ) as an assessment tool for specific quantification of dietary cruciferous vegetable exposure.
  
  
  METHODS
  Participants (n=107; 18 to 76 years old) completed a standard FFQ and the Cruciferous Vegetable FFQ twice over a 2-week period. Repeat dietary recalls were collected on 3 days over the same 2-week period. Urinary dithiocarbamate was determined as a biomarker of cruciferous vegetable intake.
  
  
  METHODS
  Descriptive statistics of intake; paired t tests and sign tests for comparison of intake estimates between instruments; Spearman correlations to assess reliability and associations between diet instruments and urinary dithiocarbamate.
  
  
  RESULTS
  Cruciferous vegetable intake was significantly correlated between the two FFQs (r(s)=0.58), although the Cruciferous Vegetable FFQ estimated intake 35 g higher than the standard FFQ. The Cruciferous Vegetable FFQ was reliable, with a repeated measures correlation of 0.69 (P</=0.01). Urinary dithiocarbamate excretion correlated with cruciferous vegetable intake from the Cruciferous Vegetable FFQ (r(s)=0.26, P<0.01), and from the standard FFQ (r(s)=0.19, P=0.06).
  
  
  CONCLUSIONS
  The Cruciferous Vegetable FFQ provided a reproducible, valid estimate of cruciferous vegetable exposure and improved the relationship between crucifer consumption and urinary dithiocarbamate, a biomarker of cruciferous vegetable exposure. The nearly twofold difference in exposure estimates between the Cruciferous Vegetable FFQ and the standard FFQ could change the statistical significance of risk estimates in the context of epidemiological research. This questionnaire is an appropriate research tool to evaluate cruciferous vegetable intake more accurately than a standard FFQ, particularly in the context of dietary intervention studies that promote increased vegetable intake to reduce the risk for chronic disease.
authors: Department of Nutritional Sciences, The University of Arizona, Tucson 85721-0038, USA. cthomson@email.arizona.edu
authors: Cynthia A
authors: CA
authors: Thomson
authors: Tara R
authors: TR
authors: Newton
authors: Ellen J
authors: EJ
authors: Graver
authors: Kelly A
authors: KA
authors: Jackson
authors: Phyllis M
authors: PM
authors: Reid
authors: Vernon L
authors: VL
authors: Hartz
authors: Ellen C
authors: EC
authors: Cussler
authors: Iman A
authors: IA
authors: Hakim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D019607:Brassicaceae / Q000378:metabolism; D004034:Diet Surveys; D004435:Eating; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D015203:Reproducibility of Results; D012650:Self Disclosure; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires / Q000592:standards*; D013859:Thiocarbamates / Q000652:urine*; D014481:United States
chemical_list: D015415:Biomarkers; D013859:Thiocarbamates