Dietary data in the Norwegian Women and Cancer Study : validation and analyses of health related aspects

The objectives of the present thesis were to design a semi-quantitative food frequency questionnaire for use in epidemiological research among Norwegian women, to validate certain components of the dietary data, to collect dietary data from a large nation-wide sample of women, and to analyse selected nutritional aspects related to health, both cross-sectionally and prospectively. The data are collected as part of the Norwegian Women and Cancer Study (NOWAC), a large population-based cohort study established in 1991. The dietary data are collected by means of self-administered food frequency questionnaires asking about usual diet during the last year. In this thesis, three different questionnaires and three different study samples are included. First, in 1991-92, 52 592 women aged 34- 49 years (mean 41.1 yrs) completed a limited food frequency questionnaire (Appendix A): Second, in 1995, 234 women aged 40-42 years participated in a validation study and completed an extended semi-quantitative food frequency questionnaire (Appendix B). Third, in 1996, 10 249 women aged 45-69 years (mean 54.8 yrs) completed a revised version of the extended semi-quantitative food frequency questionnaire (Appendix C)