title: Measuring the dietary intake of Samoans living in New Zealand: Comparison of a food frequency questionnaire and a 7 day diet record.
abstract: The purpose of this study was to determine the accuracy of a quantitative food frequency questionnaire for measuring the usual dietary intake of Samoans living in New Zealand. We compared a self-administered 89 item quantitative food frequency questionnaire (FFQ) with a 7 day diet record (DR) in a sample of 55 Samoan adults aged 20 years and over. The FFQ asked people to report their dietary intake in frequency and amount and included photos of standard serving sizes. The DR was collected over non-consecutive three and four day periods, including two weekend days. Food weighing scales and measuring cups and spoons were provided to measure food portions. Correlations between the two methods were poor for both crude (range -0.03-0.48) and energy-adjusted (range -0.12-0.54) nutrient intakes. Approximately 29-53% of people fell into the same tertile when classified by the two methods and 9-22% of subjects were grossly misclassified into opposite tertiles. Agreement was also poor when the differences in energy, fat, protein and carbohydrate intake between the methods were plotted against mean intake. Relative to an estimate of energy expenditure, both methods underestimated usual energy intake; however, underestimation occurred to a greater extent with the DR. We conclude that agreement between the two dietary assessment methods was poor and we were unable to use the DR to calibrate the FFQ. In terms of total energy, the FFQ gave a better assessment of usual dietary intake than did the DR.
authors.affiliation: Public Health Nutrition Group, Department of Community Health, Faculty of Medicine and Health Science,University of Auckland, Auckland, New Zealand.
authors.forename: A C
authors.initials: AC
authors.lastname: Bell
authors.forename: B A
authors.initials: BA
authors.lastname: Swinburn
authors.forename: H
authors.initials: H
authors.lastname: Amosa
authors.forename: R
authors.initials: R
authors.lastname: Scragg
authors.forename: S J
authors.initials: SJ
authors.lastname: Sharpe