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. DESIGN/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. STATISTICAL ANALYSES: 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
Subject(s)
Brassicaceae , Surveys and Questionnaires/standards , Thiocarbamates/urine , Adolescent , Adult , Aged , Biomarkers/urine , Brassicaceae/metabolism , Diet Surveys , Eating , Female , Humans , Male , Mental Recall , Middle Aged , Reproducibility of Results , Self Disclosure , Sensitivity and Specificity , Statistics, Nonparametric , United StatesABSTRACT
Measurement of dietary change was assessed in a systematic quota subsample (n = 397) of women recruited into the Women's Healthy Eating and Living Study between 1996 and 1998, a multicenter, randomized dietary intervention trial among breast cancer survivors. Women from the intervention and comparison arms completed the Arizona Food Frequency Questionnaire (AFFQ) and 24-hour dietary recalls at baseline (prerandomization) and at year 1 (postrandomization). Both dietary measurement methods demonstrated significant changes in intake of key intervention-associated nutrients at year 1 in the intervention group subjects compared with minimal or no change in the comparison group subjects. The reliability of the AFFQ and recalls was measured in the comparison group and showed correlations of 0.63 and 0.43, respectively. Both instruments captured differences in dietary intake associated with the diet intervention. These results demonstrate the utility of using a multimode, multimethod approach (AFFQ and 24-hour dietary recalls) to measure differences in self-reported dietary intake over time as shown in this dietary intervention trial being conducted among breast cancer survivors.
Subject(s)
Diet Records , Diet Therapy , Nutrition Assessment , Adult , Breast Neoplasms/diet therapy , Female , Humans , Interviews as Topic , Mental Recall , Middle Aged , Multicenter Studies as Topic , Randomized Controlled Trials as Topic , Surveys and QuestionnairesABSTRACT
OBJECTIVE: Increasing recognition of the potential importance of phytochemicals in the aetiology of cancer and heart diseases has highlighted the need for methods to measure individual phytochemical consumption that are sufficiently simple to be used in large epidemiological studies and whose reproducibility and accuracy have been quantified. d-Limonene is a natural component of a variety of foods and beverages and is found mainly in citrus fruits. However, d-limonene is not assessed by any nationally available analysis database. DESIGN: We designed our study to assess the d-limonene content of different citrus juices and beverages and to develop a dietary assessment instrument to measure consumption of citrus foods (fruit, juice and peel) and d-limonene intake and test it for reliability. SUBJECTS AND METHODS: A total of 120 citrus juice samples were analysed and used to develop the preliminary d-limonene database. A self-administered citrus food-frequency questionnaire was developed and administered twice to participants, separated by a 2-month interval. The questionnaire was tested for reproducibility of estimates of citrus food consumption and d-limonene intake among 120 participants. RESULTS: Correlation coefficients between the two administrations of the questionnaire ranged from 0.50 for citrus peel use to 0.82 for orange juice. Mean intakes (range) of d-limonene from citrus juices among consumers were 13.0 (0.24-141.9) mg day-1 and 13.2 (0.07-83.9) mg day-1 (r = 0.60, P < 0.001). CONCLUSION: The citrus frequency questionnaire developed in this study provided highly reproducible estimates of citrus foods, citrus peel and d-limonene intakes. This instrument may be a useful tool in studies of the associations between citrus peel use, d-limonene intake and risk for chronic disease.
