*Institute of Food Research and Nutrition, Danish Veterinary and Food Administration. **Copenhagen County Centre for Preventive Medicine, Medical Dept., Glostrup Hospital. Contributors: ANP was principal investigator and made the study design. SFA contributed to the study design of the validation study. LO contributed to the statistical analysis. MS was chief organiser of the 1914-population study. All took part in the writing of the paper. Correspondence: Agnes N Pedersen, Veterinary and Food Administration , Mørkhøj Bygade 19, DK-2860 Søborg, Denmark. phone: +45 33 95 64 43 o E-mail: anp@fdir.dk

Abstract: Background: Quality control including validation in dietary surveys is needed to reduce and detect errors which would lead to an attenuated scientific foundation for the diet-disease relationship. Especially studies in the elderly are needed because of limited knowledge of reference values, cut-off values etc. Objective: To validate a modified dietary history method (the SENECA-method) in elderly subjects. Design: A survey of Danish men and women aged 80 years, who participated in the 1914-population study in Glostrup. Subjects and method: A pilot study (n = 34) validated the dietary history against 24-h urine collections; a main study (n = 240) compared dietary history with a 3-day estimated food record. Results: Protein intake from dietary history was 10% higher than calculated protein intake from 24-h urine collections. Differences in intakes of energy and macronutrients between dietary history and 3-day food record were generally small and non-significant, and there was good agreement between the methods in classifying nutrient intakes into same tertiles. A Bland & Altman plot indicated increasing differences in energy intake between methods with increased energy intake. Evidence for under-reporting of energy intake and/or over-reporting of the physical activity level was further made plausible when physical activity ratio was compared to recognized cut-off limits. Conclusions: The modified dietary history method can be used to estimate dietary intake in 80 year old subjects, but some degree of misreporting, especially under-reporting, appears to be present. Keeping this in mind it is, however, possible to analyse dietary intake against other survey data.

Keywords: Aged, nutrition survey, survey methodology, dietary history, estimated food record, validation study, quality control.