The collection of additional data in people below the age of 50 has been carried out as NBS3 between 2008 and 2010. NBS3 participants filled out a food frequency questionnaire. Fasting blood samples were obtained for determination of thyroid function, kidney function and CRP. Also urine was collected. In total, 2011 people were invited; 1053 sent in a food frequency questionnaire and 474 participants donated blood and urine.
The questionnaire data of NBS1 and NBS2 have been used to answer a variety of research questions. To increase the compatibility and similarity in available data between the NBS and patient groups (cancer cases) that were frequently used for our research purposes, the NBS participants who had given consent for further research and were still alive were again contacted in 2008 and invited to fill out an additional questionnaire (NBS4). In total, 8109 people were approached and 5613 (69%) completed the questionnaire (see section ‘Researcher data’ for detailed information on included questions).