Validation Information: Weighed Food Diary
Bingham 1997
Validation of Dietary Assessment Methods in the UK Arm of EPIC Using Weighed Records, and 24-hour Urinary Nitrogen and Potassium and Serum Vitamin C and Carotenoids as Biomarkers
Background: In the UK EPIC validation studies, the accuracy of several methods was assessed by comparison with 16-day weighed records and the biomarkers, 24-hour urine nitrogen (N) and potassium (K), plasma carotenoids and plasma vitamin C.
Methods: Comparisons between methods were made on 156 women, studied over 1 year at 3-monthly intervals at home. On each of four occasions, volunteers completed 4 days of weighed records and provided two 24-hour urine collections and a fasting blood sample.
Results: In comparison with the 16 days of weighed records, a food frequency questionnaire (FFQ) yielded higher values mainly due to greater reported consumption of milk and of vegetables. A 24-hour recall was as good as the FFQ in placing individuals in the distribution of habitual diet from weighed records. Results obtained from a 7-day estimated record were closest to those obtained from the weighed record. Correlations between 24-hour urine excretion and dietary N intake from weighed records were high (0.78-0.87) as were those with estimated food diaries (0.60-0.70). Correlations between urine N and the FFQ and 24-hour recall were lower (0.10 to 0.27), but improved by energy adjustment using residuals for N and K which are correlated with total energy intake. Comparisons between dietary estimates and urinary K and serum carotenoids and vitamin C showed broadly similar results. Limited biomarker information amongst 200 UK EPIC participants supported the findings of the validation study.
Conclusions: UK EPIC uses three methods (the 7-day diary, an improved FFQ, and the 24-hour recall) to assess diet. 93% of first food diaries are returned completed by participants. Repeated diaries are the main dietary assessment method for nested case- control analyses.
Total number of nutrients validated: 4
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 | Mean Difference | Standard Deviation | Correlation Coefficient | Cohen's Kappa Coefficient | Percentage Agreement | Percentage Agreement Categories | Lower Limits of Agreement | Upper Limits of Agreement |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Biomarkers | Adults | Female Only | Urinary Nitrogen | 0.69 (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.
Bingham SA, Gill C, Welch A, Cassidy A, Runswick SA, Oakes S, et al. Validation of dietary assessment methods in the UK arm of EPIC using weighed records, and 24-hour urinary nitrogen and potassium and serum vitamin C and carotenoids as biomarkers. International journal of epidemiology. 1997 Jan 1;26(suppl 1):S137.1;26(suppl 1):S137.