Validation of a self-administered food-frequency questionnaire administered in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study: comparison of energy, protein, and macronutrient intakes estimated with the doubly labeled water, urinary nitrogen, and repeated 24-h dietary recall methods.
BACKGROUND
The validation of dietary assessment instruments is critical in the evaluation of diet as a chronic disease risk factor.


OBJECTIVE
The objective was to assess the validity of a self-administered food-frequency questionnaire by comparison with dietary recall, urinary nitrogen excretion, and total energy expenditure data.


METHODS
Over a 1-y period, data from twelve 24-h dietary recalls, a food-frequency questionnaire, and four 24-h urine samples were obtained from 134 study participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) Study in Potsdam, Germany. In a substudy of 28 participants, total energy expenditure from doubly labeled water measurements was assessed.


RESULTS
Energy-adjusted, deattenuated correlation coefficients between the questionnaire and the recalls ranged from 0.54 for dietary fiber to 0.86 for alcohol. Cross-classification of quintiles of nutrient intakes from the questionnaire and recalls indicated severe misclassification to be <4%. Reported protein intake correlated with estimated protein excretion (r = 0.46). Energy intake and total energy expenditure were also significantly correlated (r = 0.48); however, all but one subject underreported their energy intake. The magnitude of underreporting varied considerably, by 22% on average, and increased slightly with increasing energy intake. A similar pattern of underreporting was observed when energy intakes from the 24-h dietary recalls were compared with total energy expenditure.


CONCLUSIONS
These data indicate an acceptable relative validity of the food-frequency questionnaire in this study population. Compared with measurements of total energy expenditure and protein excretion, however, only moderate agreement with both the food-frequency questionnaire and the 24-h dietary recalls was observed.
Kroke
A
A
Departments of Epidemiology, Intervention Studies, and Nutritional Biochemistry and Physiology, German Institute of Human Nutrition, Potsdam-Rehbruecke, Germany. Kroke@www.dife.de
Klipstein-Grobusch
K
K
Voss
S
S
Möseneder
J
J
Thielecke
F
F
Noack
R
R
Boeing
H
H
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D015992:Body Mass Index; D015331:Cohort Studies; D017666:Deuterium Oxide / Q000652:urine; D004034:Diet Surveys; D004044:Dietary Proteins / Q000008:administration & dosage*; D002149:Energy Intake / Q000502:physiology*; D005060:Europe; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D010104:Oxygen Radioisotopes / Q000652:urine; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires / Q000592:standards*; D014508:Urea / Q000652:urine
D015415:Biomarkers; D004044:Dietary Proteins; D010104:Oxygen Radioisotopes; D014508:Urea; D017666:Deuterium Oxide