The current case-control study was nested within the EPIC cohort, which is an ongoing multi-centre prospective study that recruited more than 520,000 healthy individuals between 1992 and 2000. Baseline non-dietary and dietary questionnaires were completed at enrolment, as well as anthropometric measurements and blood samples which were collected during an enrolment examination at a study centre. Detailed study descriptions of recruitment, follow-up, collection of questionnaire data and blood samples in EPIC have been provided elsewhere (20).
