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Validation Information: 7 day Estimated Food Diary

Mckeown 2001

Use of biological markers to validate self-reported dietary intake in a random sample of the European Prospective Investigation into Cancer United Kingdom Norfolk cohort

Background: The validity of dietary assessment methods should be established before diet-disease associations are reported.

Objective: Our objective was to validate a 7-d food diary and a food-frequency questionnaire (FFQ) against independent biomarkers of intake in urine (nitrogen, potassium, and sodium) and blood (plasma ascorbic acid).

Design: A total of 146 healthy middle-aged men and women were recruited from the European Prospective Investigation into Cancer UK Norfolk cohort, a free-living cohort of ∼25000 persons. Over a 9-mo period, urinary nitrogen, potassium, and sodium were estimated from 2-6 complete 24-h urine collections in 134 subjects and plasma ascorbic acid was estimated from 2-3 fasting blood samples in 118 subjects. Subjects completed 2 FFQs and two 7-d food diaries.

Results: In men and women combined, correlations between 24-h urinary nitrogen excretion and dietary intake from the 7-d food diary were high (r = 0.57-0.67) compared with those for the FFQ (r = 0.21-0.29). Similarly, correlations between urinary potassium and dietary potassium were higher for the 7-d food diary (r = 0.51-0.55) than for the FFQ (r = 0.32-0.34). There was no overall difference in correlations between plasma ascorbic acid and dietary vitamin C between the 7-d food diary (r = 0.40-0.52) and the FFQ (r = 0.44-0.45).

Conclusions: These data indicate that, despite increased subject burden, the 7-d food diary provided a better estimate of nitrogen and potassium intakes than did the FFQ in this study population. However, with respect to plasma ascorbic acid, both the FFQ and
7-d food diary provided a similar ranking of subjects according to vitamin C intake.

Web Link

Validation Information

Year of Publication

Tool Information

Dietary Exposure Measured
Macronutrient, Micronutrient
Tool Type
Food Diary Estimated
Timeframe Tool Measures info
1 Day
Portion Size Measures info
Colour photographs of 17 foods, each with 3 different portion sizes. Weights and household measures were also used when appropriate.
Reporting Method info
Format info
Supplements Measured
Administration Method info

Study Information

Study Location
Norfolk, England
Associated Nutrient Database
Comparator Validated Against


Sample Size
57 (Male), 77 (Female), 134 (All)
Adults, Elderly
Age of Population

Range: 45-75 years

Mean(SD): 60(10) years (Male); 58(10) years (Female)

Male Only, Female Only, Both
Other Notable Characteristics
Healthy Population who had participated in the main EPIC study

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: 1
  • Micronutrients: 3
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
Biomarkers Adults, Elderly Male Only Sodium (mg) 0.39 (S)
Plasma Ascorbic Acid (µmol/L) 0.41 (P)
Urinary Nitrogen 0.51 (S)
Biomarkers Adults, Elderly Female Only Sodium (mg) 0.17 (S)
Plasma Ascorbic Acid (µmol/L) 0.56 (P)
Urinary Nitrogen 0.48 (S)
Biomarkers Adults, Elderly Both Sodium (mg) 0.48 (S)
Plasma Ascorbic Acid (µmol/L) 0.53 (P)
Urinary Nitrogen 0.66 (S)

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.

McKeown NM, Day NE, Welch AA, Runswick SA, Luben RN, Mulligan AA, et al. Use of biological markers to validate self-reported dietary intake in a random sample of the European Prospective Investigation into Cancer United Kingdom Norfolk cohort. The American journal of clinical nutrition. 2001 Aug 1;74(2):188-96.