Development of a food frequency questionnaire to estimate calcium intake of Asian, Hispanic, and white youth

Objective To develop a food frequency questionnaire (FFQ) that estimates calcium intake of Asian, Hispanic, and white youth living in the western United States. Design A list of 80 foods was assembled to create an FFQ to measure calcium intake. Evaluation of the FFQ spanned four consecutive weeks. An FFQ was completed during Week 1 and Week 4, and a 24-hour dietary recall was completed during Week 2 and Week 3. Subjects/setting A convenience sample of 162 Asian, Hispanic, and white youth ages 10 to 18 years was selected. Statistical analyses performed Percent agreement, paired t tests, Pearson correlation coefficients of cube-root transformed values, and deattenuated Pearson correlation coefficients of cube-root transformed values were used to evaluate the FFQ. Results The correlation between calcium intake estimates, when measured by first and second administrations of the FFQ, was 0.68 (Pearson's r) for the total sample. Correlations differed by age, sex, and ethnic subgroups as follows: 10 to 13 years (r=0.62), 14 to 18 years (r=0.73), male (r=0.73), female (r=0.64), Asian (r=0.77), Hispanic (r=0.72), and white (r=0.48). The correlation between calcium intakes as estimated by the second FFQ vs the average of the two 24-hour dietary recalls was 0.54 (deattenuated Pearson's r) for the total sample. This correlation differed by age, sex, and ethnic subgroups as follows: 10 to 13 years (r=0.46), 14 to 18 years (r=0.59), male (r=0.65), female (r=0.45), Asian (r=0.64), Hispanic (r=0.18), and white (r=0.57). Conclusions A unique dietary survey has been developed to estimate calcium intake among Asian, Hispanic, and white youth in the United States.