Validation of a food frequency questionnaire for assessing dietary nutrients in Brazilian children 5 to 10 years of age

Objective This study aimed to assess the relative validity of a food frequency questionnaire (FFQ), previously validated to measure usual intakes in adults, for measuring dietary intakes in children 5 to 10 y of age. Methods Dietary intakes were measured using an FFQ and a 3-d dietary record. Healthy children, 5 to 10 y old (n = 151), were recruited from public schools and asked to answer the questions in the FFQ and to provide non-consecutive 3-d dietary records based on reported estimated portion sizes. Paired sample t tests and Pearsonʹs correlation coefficients were conducted to determine whether the two instruments reported similar values for energy and nutrients. The agreement of quartile categorization between the two instruments was also examined. Results Estimated energy and nutrient intakes derived from the FFQ were significantly higher than those derived from 3-d dietary records. As expected, Pearsonʹs correlations increased after adjusting for residual measurement error, presumably due to exclusion of the high within-person variability in intake of these nutrients. Moderate to high (r > 0.50) correlation coefficients were verified for some nutrients such as calcium, folate, vitamin B2, vitamin A, and vitamin C. Conclusion This FFQ, originally developed for use in adults, appears to overestimate usual energy and nutrient intakes in children 5 to 10 y of age. Further work is necessary to conduct a calibration study to establish adequate portion sizes before instrument adoption in this population.