• Teresa A Marshall, Julie M Eichenberger Gilmore, Barbara Broffitt, Phyllis J Stumbo, and Steven M Levy.
• Department of Preventive and Community Dentistry, University of Iowa College of Dentistry, N335 Dental Science Bldg, Iowa City, IA 52242, USA. teresa-marshall@uiowa.edu
• J Am Diet Assoc. 2008 Mar 1;108(3):465-72.

ObjectiveFood frequency questionnaires are commonly developed and subsequently used to investigate relationships between dietary intake and disease outcomes; such tools should be validated in the population of interest. We investigated the relative validities of the Iowa Fluoride Study targeted nutrient semi-quantitative questionnaire and Block Kids' Food Questionnaire in assessing beverage, calcium, and vitamin D intakes using 3-day diaries for reference.DesignCross-sectional.SubjectsChildren who completed Iowa Fluoride Study nutrient questionnaire at age 9.0+/-0.7 years (n=223) and/or the Block Kids' Food Questionnaire at age 8.3+/-0.3 years (n=129) and 3-day diaries during similar time periods.Main OutcomesIntakes of beverages, calcium, and vitamin D.Statistical AnalysesSpearman correlation coefficients, weighted kappa statistics, and percentages of exact agreement were used to estimate relative validities.ResultsCorrelations between milk intakes (r=0.572) reported on diaries and the Iowa Fluoride Study nutrient questionnaires were higher than correlations for 100% juice, juice drinks, soda pop, and water (r=0.252 to 0.379). Correlations between milk intakes (r=0.571) and 100% juice intakes (r=0.550) reported on diaries and Block Kids' Food Questionnaires were higher than correlations for other beverages (r=0.223 to 0.326). Correlations with diaries for calcium (r=0.462) and vitamin D (r=0.487) intakes reported on Iowa Fluoride Study nutrient questionnaires were similar to correlations with diaries for calcium (r=0.515) and vitamin D (r=0.512) reported on Block Kids' Food Questionnaires. Weighted kappa statistics were similar between the Iowa Fluoride Study nutrient questionnaires and the Block Kids' Food Questionnaires for milk, 100% juice, and vitamin D, but were higher on the Iowa Fluoride Study nutrient questionnaires than on the Block Kids' Food Questionnaires for calcium. Percentages of exact agreement were higher for calcium, but lower for vitamin D for intakes reported on the Iowa Fluoride Study nutrient questionnaires compared to the Block Kids' Food Questionnaires relative to diaries.ConclusionsBoth the Iowa Fluoride Study nutrient questionnaire and the Block Kids' Food Questionnaire provide reasonable estimates of milk, calcium, and vitamin D intakes when compared to 3-day diaries.

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