Further details of the health check and laboratory protocols for the analysis of the blood and urine samples are available here. A calibration exercise was undertaken regularly to check on accuracy of both equipment and operators at a meeting of the nurses and co-ordinators in Norfolk.

At the end of the health check, the nurse gave the participant guidance on how to complete the remaining questionnaire, the seven-day food diary. The diary required participants to record in detail what they ate and drank over a period of a week. The nurses received special training in dietary survey methods to ensure that participants recorded their diet accurately, and that nurses were not 'judgmental' about food intake. As a result, 93% of participants completed the food diary. The diaries were completed to a very high standard, some people sending recipes and packaging from foods. This helped us to identify accurately the nutritional composition of their diet.

All the results from the health check, including blood pressure and cholesterol levels, were sent to the participant's GP, who was responsible for any further follow-up and treatment.

After the baseline measurements, a calibration study was carried out on a sample of 600 EPIC-Norfolk participants. This used a standardised, computerised 24-hour diet recall method (EPIC-SOFT) to enable dietary comparisons to be made between the 10 countries taking part in EPIC. Weight and height measurements were taken and 24-hour urine collections made.

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