Copenhagen County Centre for Preventive Medicine, Research Unit for Dietary Studies, Medical Dept M, Glostrup University Hospital, Glostrup, Denmark. sh@ipm.hosp.dk
OBJECTIVE: To examine the quantitative agreement between a 7 day food record and a diet history interview when these are conducted under the same conditions and to evaluate whether the two methods assess habitual diet intake differently among subgroups of age and body mass index (BMI). DESIGN: Cross-sectional study. SETTING: Population study, Denmark. SUBJECTS: A total of 175 men and 173 women aged 30-60 y, selected randomly from a larger population sample of Danish adults. INTERVENTIONS: All subjects had habitual diet intake assessed by a diet history interview and completed a 7 day food record within 3 weeks following the interview. The diet history interview and coding of records were performed by the same trained dietician. MAIN OUTCOME MEASURE: Median between-method difference in assessment of total energy intake, absolute intake of macronutrients, and nutrient energy percentages. Difference between reported energy intake from both methods and estimated energy expenditure in different subgroups. RESULTS: Energy and macronutrient intake was assessed slightly higher by the 7 day food record than by the diet history interview, but in absolute terms the differences were negligible. The between-method difference in assessment of total energy intake appeared to be stable over the range of age and BMI in both sexes. As compared to estimated total energy expenditure, both diet assessment methods underestimated energy intake by approximately 20%. For both methods the under-reporting increased by BMI in both sexes and by age in men. CONCLUSIONS: Energy and macronutrient intake data collected under even conditions by either a 7 day food record or a diet history interview may be collapsed and analysed independent of the underlying diet method. Both diet methods, however, appear to underestimate energy intake dependent on age and BMI. SPONSORSHIP: Danish Medical Research Council, the FREJA programme.