Background: The food frequency questionnaire (FFQ) is the most efficient and cost-effective method to investigate the relationship between usual diet and disease in epidemiologic studies. Although FFQs have been validated in many adult populations worldwide, the number of valid FFQ in preschool children is very scarce. The aim of this study was to evaluate the reproducibility and validity of a semi-quantitative FFQ designed for children aged 4 to 5 years.
Materials and methods: In this study, we have included 169 children aged 4-5 years from the INMA project in Valencia, a population-based prospective cohort study of mothers and children in Spain. The 105-items FFQ was administered twice to the parents or care-givers of children over a 9-month period. Reproducibility was explored by comparing intake of nutrients by the FFQs, while validity was examined by comparing the nutrient values from the FFQs with the average nutrient values of three 24 hour dietary recall (24hDR) taken in the period, and also, with the concentration in blood specimens for several vitamins (carotenoids, folate, vitamin B12, vitamin C and α-tocopherol). Pearson correlation coefficients and de-attenuated correlation coefficients were calculated and we also evaluated misclassification by quintile distribution.
Results: All correlation coefficients for reproducibility for nutrients and major food groups were statistically significant; the average correlation coefficients for daily intake were 0.43 for food groups and 0.41 for nutrients. The average correlation coefficients for validity for daily intakes against 24hDR was r = 0.30, and the average for de-attenuated correlation coefficients was r = 0.44. When evaluating validity against the blood concentration of vitamins, statistically significant correlations were observed for vitamin C (0.35), lycopene (0.31), β-Cryptoxantin (0.40), and vitamin E (0.29); the average of correlation coefficients was r = 0.21.
Conclusion: Despite some low to moderate correlations for reproducibility and validity, overall this study suggests that the FFQ may be a good method for assessing a wide range of food groups and nutrients intake in children aged 4-5 years.