Comparison of a short food-frequency questionnaire and derived indices with a seven-day diet record in Belgian and Italian children

To compare food group intakes and dietary indices estimated from a 14-item food frequency questionnaire (FFQ) with a seven day diet record. 112 Belgian and 114 Italian children (11-12 years) completed the FFQ followed by a seven-day diary (FD) and a retest one week later. Dietary indices were calculated from the FFQ and the FD. Spearman's correlations between the FFQ items and the diary varied between -0.13 and 0.67. When comparing the FFQ with the FD an overestimation was found for most items. The Excess Index was significantly correlated with energy intake (respectively 0.35 and 0.25 for Belgian and Italian children); the Variety Index with fiber intake (0.26 for both) and Calcium intake (respectively 0.32 and 0.41); the Fiber Index with fiber intake (respectively 0.30 and 0.37) and the Calcium Index with Calcium intake (respectively 0.47 and 0.50). When the FFQ is used for estimating consumption frequencies, overestimation must be considered. The ability to rank individuals varies considerably between food items. The Calcium index can be useful in situations requiring brief dietary instruments. The value of the other indices is lower although still associations in the expected directions were found.