A self-completed 24hDR was sent out to all potential EPIC-Norfolk participants with the invitation to join the study. A second 24hDR was sent out with the invitations to the 2HC three years later. This short questionnaire asked for a record of all food and drink consumed the previous day.

Completed 24hDRs were returned by post. Those that participated in the health check went on to complete a 7dDD. For those who did not attend a health check the 24hDR is the only dietary data collected.

The 24hDRs were coded using DINER.