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Validation Information: German EPIC FFQ1

Boeing 1997

The Relative Validity of Vitamin Intakes Derived from a Food Frequency Questionnaire Compared to 24-Hour Recalls and Biological Measurements: Results from the EPIC Pilot Study in Germany

Background:For the European Prospective Investigation into Cancer and Nutrition (EPIC) study Germany, a self-administered food frequency questionnaire (FFQ) was developed and tested for its relative validity and reproducibility in 1991/1992. Study participants were 92 potential cohort members. This paper reports results regarding retinol, carotenoids, tocopherols and ascorbic acid.

Methods:Study participants were invited to the study centre in Heidelberg once a month over one year. At each visit, a 24 hour recall was obtained. The FFQ was filled in twice with a 6-month interval (FFQ1, FFQ2). In addition, a questionnaire on general consumption frequencies of 14 broad food groups was completed. This information was combined with estimates derived from FFQ2 and frequency-corrected food and nutrient intakes were calculated (FFQcorr). Blood specimens were taken in winter and summer 1992.

Results:The intraclass correlation of the FFQ ranged from 0.65 to 0.67 for retinol, tocopherols, carotenoids, and ascorbic acid. Intake of carotenoids by FFQcorr showed de-attenuated Pearson correlation coefficients with blood values in the order of 0.37, and with recall data of 0.44. Respective correlations for retinol were 0.21 and 0.29, for tocopherols 0.18 and 0.52, and for ascorbic acid 0.36 and 0.69. Errors of FFQcorr and 24-hour diet recalls were not correlated.

Conclusions:In general, it was demonstrated that the FFQ was able to rank participants into biologically meaningful categories of intake or blood concentrations for carotenoids and ascorbic acid, but misclassification was higher for tocopherol and retinol.

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Validation Information

Year of Publication

Tool Information

Dietary Exposure Measured
Energy, Macronutrient, Micronutrient, Food Groups
Tool Type
Food Frequency Questionnaire
Timeframe Tool Measures info
1 Year
Portion Size Measures info
87 coloured portion size photographs.
Reporting Method info
Usual; Retrospective
Format info
Supplements Measured
Not Reported
Administration Method info

Study Information

Study Location
Heidelberg, Germany
Associated Nutrient Database
Bundeslebensmittelschlüssel BLS, version II.1
Comparator Validated Against
24hr Recall, Biomarkers


Sample Size
92 (24hr Recall), 92 (Biomarkers)
Age of Population

Range: 35-64 years

Mean(SD): 48 years (Male); 49 years (Female)

Other Notable Characteristics

Total number of nutrients validated: 4 info

Not all of the nutrients validated in the validation studies are included in the table below, as statistical data was only selected to be displayed for a number of nutrients, this included:

  • Energy
  • Fat
  • Saturated Fat
  • Mono-unsaturated Fat
  • Poly-unsaturated Fat
  • Carbohydrates
  • Protein
  • Sugar
  • Non‐starch polysaccharides(NSP)
  • Sodium
  • Calcium
  • Iron
  • Zinc
  • Retinol
  • Folate
  • Folic Acid
  • Vitamin B12
  • Vitamin C
  • Fruit & Vegetables
  • Urinary Nitrogen

To find information on the other validated nutrients please read the validation study.

  • Macronutrients: 0
  • Micronutrients: 4
Comparator Lifestage Sex Nutrient Measured info Mean Difference Standard Deviation info Correlation Coefficient info Cohen's Kappa Coefficient Percentage Agreement Percentage Agreement Categories info Lower Limits of Agreement Upper Limits of Agreement
24hr Recall Adults Both Retinol (µg) 0.22 (P)
Vitamin C (mg) 0.61 (P)
Biomarkers Adults Both Retinol (µg) 0.19 (P)
Vitamin C (mg) 0.24 (P)

Some results have been calculated using statistical techniques based on the published data.

For further information on statistical terms click on Statistical tests used in validation studies

All correlations coefficients in the table are unadjusted unless stated otherwise. For adjusted correlation coefficients and other statistical methods used in the study e.g. paired t-tests, please read the validation articles.

  • # Adjusted
  • † Energy adjusted.
  • ‡ For loge-transformed, energy-adjusted nutrient intakes.
  • ^ Adjacent included.
  • ᵟ Participants provided identical responses.
  • (w) = Weighted.

Boeing H, Bohlscheid-Thomas S, Voss S, Schneeweiss S, Wahrendorf J. The relative validity of vitamin intakes derived from a food frequency questionnaire compared to 24-hour recalls and biological measurements: results from the EPIC pilot study in Germany. European Prospective Investigation into Cancer and Nutrition. International journal of epidemiology. 1997;26 Suppl 1:S82-90.