Comparison of a quantitative dairy questionnaire with a dietary history in young adults

There is growing interest in the potential role of calcium in the prevention of osteoporosis. Therefore a quantitative dairy questionnaire (DQ) was developed to estimate the calcium intake from dairy products. The aim of this study was to evaluate the relative validity and reproducibility of the DQ in 27-29 year old males and females.

The DQ was validated against a cross-check dietary history method (DH) in 160 subjects, and the reproducibility was assessed in 29 subjects by repeating the administration of the DQ with a one-year interval.

In the validity study, the nutrient calcium and the food groups cheese and milk and milk products measured by the DQ tend to show higher intakes as compared to the results of the DH. However, only for the calcium intake was the difference between the DQ and DH (7%) significant. The Bland-Altman plot showed that this bias was constant over the range of calcium intakes. The Pearson correlation coefficients between the DQ and the DH varied from 0.58 to 0.65. On average, about 52% of the subjects were classified in the same quartile in the DQ and the DH for the intake of calcium as well as dairy products. The weighted kappas were between 0.60 and 0.67. In the reproducibility study, the Pearson correlation coefficient for the calcium intake assessed by the DQ one year apart was 0.78.

These data indicate that the DQ is reasonably accurate in young adults as a means of assessing the calcium intake from dairy products.