A rapid self-administered food frequency questionnaire for the evaluation of dietary protein intake

Background Dietary calcium and proteins are important determinants of bone health. Among the various methods to evaluate dietary intakes, food frequency questionnaires provide a self-administered, quick and simple estimation of dietary intakes. Objectives To validate a simple, rapid, self-administered food frequency questionnaire for the estimation of dietary protein intake. Design and methods A self-administrable food frequency questionnaire comprising 20 items was developed. The accuracy of dietary protein evaluation by this questionnaire was verified by comparing it to the results of a diary performed over a 4-day-period in 29 normal healthy subjects (mean age±SD, 40.1±12.3), and to the mean of three last 24-h recalls, administered at 6-week intervals in 43 healthy men (mean age±SD, 51.2±5.1). Results As compared with the values from both reference methods, the slope coefficient of linear regression analysis was statistically different from zero, but the percent of variance explained by the frequency questionnaire results amounted to 35% (diary) and 18% (24-h recall), respectively. Bland and Altman graphs as well as the Pitmanʹs test did not show any difference in variability between the reference methods and the new food frequency questionnaire. This indicates a reliable estimate of group average dietary protein intakes. Conclusion This rapid, self-administered food frequency questionnaire could be a useful tool for the evaluation of dietary protein intakes in groups of subjects.