Objective: The validity of the 24-hour recall, 3-day food record, and 5-day food frequency was assessed to decide on a dietary assessment method for the National Heart, Lung, and Blood Institute (NHLBI) Growth and Health Study.
Design: All subjects were assigned to one of three dietary assessment methods. Unobtrusive observers recorded types and amounts of foods eaten during lunch, and these were compared with the foods reported by the girls in the study.
Setting: School lunchrooms in California and Ohio.
Subjects: 58 girls, aged 9 and 10 years.
Main outcome measures: Reporting errors for dietary assessment methods.
Statistical analyses performed: Descriptive statistics, matched pair t tests, and Spearman correlation coefficients.
Results: Comparison of the intakes of energy and selected macronutrients showed different ranges of, and median percentage absolute errors for, each dietary assessment method. Percentage absolute errors ranged between 20 and 33 for the 5-day food frequency method; 19 and 39 for the 24-hour recall; and 12 and 22 for the 3-day food record. The proportion of missing foods (ie, observed food items not reported) and phantom foods (ie, reported food items not observed) by each method were 46% and 40%, respectively, for the 5-day food frequency; 30% and 33%, respectively, for the 24-hour recall; and 25% and 10%, respectively, for the 3-day food record.
Applications/conclusions: Errors in food reporting and quantification can vary with the type of dietary methodology. Agreement between observed and reported intakes from 3-day food records made it the best overall choice. On this basis, it was selected as the method of assessment for the NHLBI Growth and Health Study.