The 14-page questionnaire was designed to capture the habitual food intake among Norwegian adults the preceding year. The FFQ was an extended and revised version of the semi-quantitative food-frequency questionnaire used in the Norwegian nation wide survey NORKOST 1997 (NFFQ). The original NFFQ was a validated, 180 items optical readable FFQ, developed to cover 100% of the total EI of the population [3 -6 (link)]. Based on our extensive screening of antioxidant content in foods and beverages [7 (link)], the NFFQ was updated and revised with questions about food products and food categories assumed to be important sources of antioxidant intake in Norway. The new FFQ included 270 food items, grouped together according to the Norwegian meal pattern. Additional questions were added concerning intake of several food categories. In detail, 19 questions about berries, 4 questions about fruit, 6 questions about vegetables, 2 questions about chocolate, 3 questions about coffee and 2 questions about tea were added. Questions concerning the variable intake of berries due to seasonal variations were included. Furthermore, 10 questions were added about nuts and seeds and 27 questions about spices and herbs. The options of frequency of consumption of particular food items varied from several times a day to never/seldom, with portion sizes based on typical household units: slices, glasses, cups, pieces, spoons and teaspoons. When frequency was answered but not portion size, the food item was given the smallest portion size. When portion size was answered but not frequency, the food item was given the value zero. One participant was excluded from the study because a substantial amount of the questions in the FFQ were left unanswered. The dietary questions totaled 11 pages of the questionnaire whereas the last 3 pages were dedicated to questions concerning dietary supplements, smoking, physical activity and past and present illnesses and medication. The answered FFQs were scanned and the image files translated into data files using the Cardiff Teleform 2006 software.
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