Reproducibility and validity of a food frequency questionnaire among women of Japanese ancestry living in Brazil

A 120-item food frequency questionnaire (FFQ) was assessed among Female Registered Dietitians of Japanese ancestry living in Sao Paulo, Brazil. The reproducibility of the FFQ was assessed by repeated administration at one-month interval (n = 77). The relative validity was evaluated by comparison with dietary intake obtained from 4 three-day weighed dietary records (DR), covering the same 12-month period assessed by the FFQ (n = 52). Reproducibility: Pearson correlation coefficients for 24 energy-adjusted nutrients ranged from 0.52 for protein to 0.75 for retinol. Validity: Pearson correlation coefficients between the mean energy-adjusted intakes from the DR and those from the FFQ ranged from 0.27 for sodium to 0.68 for dietary fiber without supplements. These correlations were higher after adjusting for day-to-day variation in DR intakes. We conclude that this FFQ is reproducible and can be used to classify persons according to their nutrient intake over a one-year period. (C) 2001 Elsevier Science Inc. Ah rights reserved.