Validation of a food frequency questionnaire for retrospective estimation of diet during the first 2 years of life.

This study aims to validate a Food Frequency Questionnaire (FFQ), specifically designed to retrospectively estimate dietary intake and supplement consumption during the first 2 years of life in children from resource poor households in semi-rural Mexico. The FFQ querying about diet during the first 2 years of life was administered to mothers of children (N = 84), who participated in a prospective study 3-5 years earlier, in which complementary feeding practice questionnaires and 24-h recall (24hrR) were collected at several time points during the first 2 years of life to evaluate dietary and vitamin supplement intake. The resulting FFQ data were compared to intake data collected during the original study using Spearman correlations, deattenuated correlations and Wilcoxon signed-rank tests. Total energy intake, as estimated by the retrospective and original instruments, did not differ in the second year (Yr2); correlations between the measures were significant (r = 0.40, p < 0.001). The 24hrR and FFQ-Yr2 were significantly correlated for dietary intake of vitamins B6, B12 (p < 0.001) and folate (p < 0.01); however, after including vitamin supplement intake, the two dietary instruments were correlated only for vitamins A and B12 (p < 0.05). The FFQ provides a reasonable estimate of a child's dietary intake of energy and key micronutrients during the second year of life, and permits accurate ranking of intake 3-5 years after birth.