Development and validation of the semi-quantitative brief food frequency questionnaire to assess the magnesium intake in young women.

Abstract

The aim of the study was to develop and validate the semi-quantitative brief food frequency questionnaire to assess the magnesium intake (Mg-FFQ). The developed questionnaire consists of 39 questions and it was validated in a group of 75 women aged 20-30. The validity was assessed with reference to the 3-day dietary record and the reproducibility was assessed for a period of 6 weeks. The Bland-Altman index for the assessment of validity was 6.7% and for reproducibility-8.0%, while the kappa statistic indicated a slight and substantial agreement, respectively. The high reproducibility was confirmed by a high share of respondents correctly classified into tertiles (73.3%) and correctly classified into categories of adequate/inadequate intake (85.3%). For the developed and validated Mg-FFQ, a high reproducibility, accompanied by a satisfactory validity, was confirmed, so it may be used to assess the magnesium intake in the epidemiological studies in young Polish women aged 20-30.