Validation of the food frequency questionnaire with the 4-day record method and analysis of 24-h urinary nitrogen

OBJECTIVE: To validate a semi-quantitative food frequency questionnaire (FFQ). DESIGN: FFQ was evaluated by a 4-day food record (FR), four consecutive 24-h urinary collections, and study-specific cut-off limits for ratio between energy intake (EI) and basal metabolic rate (BMR). SETTING: Department of geriatric medicine, Goteborg University, Vasa Hospital, Gothenburg, Sweden. SUBJECTS: 76 consecutive 70-year-olds from representative population studies. RESULTS: FFQ provided consistently higher intakes of energy and nutrients than