Validity of a food frequency questionnaire in the assessment of vitamin A intake when compared to an eight day diet record.
Abstract: Background: Food frequency questionnaires are a method of dietary assessment which has been used in healthcare practices since the early 1950's (1). These assessments are used in the evaluation of large populations nutrient intakes based on food frequency consumption. (2) On the other hand diet records are a complete and accurate account of exact food types and quantities consumed by individuals and have the ability to measure exact nutrient levels. (2) This study looks to compare and contrast the two research methods in relation to determining vitamin A intake. Objective: To evaluate the efficacy and validity of a student administered food frequency questionnaire in the assessment of vitamin A intake in comparison to an eight day dietary record. Design: Cross-sectional dietary survey using a food frequency questionnaire and an eight day diet record.
A FFQ was specifically designed to include vitamin A rich foods along with those of which were seen to be commonly consumed and contain relevant levels. 16 University of Otago nutrition students completed the FFQ, and from the results obtained specific individual's average daily vitamin A intakes were calculated. A previously completed eight day diet record was use as a comparison, the results of which were used to contrast the vitamin A consumed from within each diet. The results from both the 8DDR and FFQ were then ranked into quartiles according to their average vitamin A intake per individual and a contingency table was assembled. Mean vitamin A levels per quartile were calculated along with the standard deviation which were tabulated and graphed in order to establish statistical significance via student paired t-tests and their corresponding p-values. Results: When compared to the eight day...