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Validation Information: FFQ (Protein and potassium)

Geelan 2014

Comparison of approaches to correct intake-health associations for FFQ measurement error using a duplicate recovery biomarker and a duplicate 24h dietary recall as a reference method

Objective: To illustrate the impact of intake-related bias in FFQ and 24-hr recall and correlated errors between these methods, on intake–health associations. Design: Dietary intake was assessed by a 180-item semi-quantitative FFQ and two 24-hr recalls. Urinary N and urinary K were estimated from two 24 -hr urine samples. We compared four scenarios to correct associations for errors in an FFQ estimating protein and K intakes. Setting: Wageningen, the Netherlands. Subjects: Fifty-nine men and fifty-eight women aged 45–65 years. Results: For this FFQ, measurement error weakened a true relative risk of 2.0 to 1.4 for protein and 1.5 for K. As compared with calibration to duplicate recovery biomarkers (i.e. the preferred scenario 1), estimating a validity coefficient using this duplicate biomarker resulted in overcorrected associations, caused by intake-related bias in the FFQ (scenario 2). The correction factor based on a triad using biomarkers and 24-hr recall was hampered by this intake-related bias and by correlated errors between FFQ and 24-hr recall, and in this population resulted in a nearly perfect correction for protein but an overcorrection for K (scenario 3). When the 24-hr recall was used for calibration, only a small correction was done, due to correlated errors between the methods and intake-related bias in the 24-hr recall (scenario 4).Conclusions: Calibration to a gold standard reference method is the preferred approach to correct intake–health associations for FFQ measurement error. If it is not possible to do so, using the 24-hr recall as reference method only partly removes the errors, but may result in improved intake–health associations.

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Validation Information

Year of Publication

Tool Information

Dietary Exposure Measured
Macronutrient, Micronutrient
Tool Type
Food Frequency Questionnaire
Timeframe Tool Measures info
1 month
Portion Size Measures info
Portions sizes were estimated using household measures and standard units.
Reporting Method info
Format info
Supplements Measured
Not reported
Administration Method info

Study Information

Study Location
Associated Nutrient Database
The 2006 Dutch Food Composition Table
Comparator Validated Against
24hr Recall


Sample Size
59 (Male), 58 (Female)
Adults (45-65 years)
Age of Population

Mean (SD): 57.4 (4.3) years

Male Only, Female Only
Other Notable Characteristics
Subjects were recruited by convenience sampling from Wageningen, The Netherlands

Total number of nutrients validated: 2 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: 1
  • Micronutrients: 1
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 (45-65 years) Male Only Protein -24.5 -7.7
24hr Recall Adults (45-65 years) Female Only Protein -11.3 -5.6

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.

Geelen A, Souverein O.W, Busstra M.C, de Vries J.H.M. & van t Veer P. Comparison of approaches to correct intake health associations for FFQ measurement error using a duplicate recovery biomarker and a duplicate 24h dietary recall as a reference method. (2014. Public Health Nutrition. 18 (2) 226-233