A self-administered semiquantitative food-frequency questionnaire with optical reading and its concurrent validation.

An improved semiquantitative self-administered food frequency questionnaire has been designed in order to investigate possible associations between diet and health, to plan nutrition education programmes, and to examine dietary compliance. The questionnaire consists of 16 printed forms and 16 pages with coloured photos of the most common foods and courses from the Italian diet. Instructions and other questions are included. The questionnaire uses optical reading from a scanner connected to a personal computer. The questionnaire was validated by comparing it with the seven-day weighed record method using 46 healthy adult volunteers. Significant correlations were found for all nutrients tested (Spearman rank correlation procedure), r ranging from 0.33 for ascorbic acid to 0.84 for alcohol. The two methods gave comparable results (Wilcoxon matched-pairs signed rank test) for all nutrients except riboflavin and alcohol. Similarity of the two methods in classifying relative intakes was examined by determining the frequency of similar classification into tertiles. Half of the subjects were correctly classified for most nutrients and for frequency of consumption of 18 food groups.