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 validity of dietary assessment methods should be established before diet-disease associations are reported.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).A total of 146 healthy middle-aged men and women were recruited from the European Prospective Investigation into Cancer UK Norfolk...