EVALUATION OF A QUANTITATIVE FOOD FREQUENCY QUESTIONNAIRE USED IN A GROUP OF NORWEGIAN ADOLESCENTS

Objective. The study was conducted to assess the reproducibility and v alidity of a 190-item self-administered quantitative food frequency qu estionnaire, used in a nation-wide study of adolescents. Design and su bjects: Reproducibility study; 103 11th grade students (18 years) comp leted the questionnaire twice, with a 6-week interval. Validation stud y; 49 11th grade students filled in the questionnaire and kept 7-day w eighed food records. Results: Spearman rank correlations between the n utrient intakes from the two questionnaires varied from 0.63 (sugar en ergy percentage) to 0.91 (alcohol). The median coefficient was 0.85. T he first questionnaire produced generally higher nutrient intake estim ates than the second. Correlations between nutrient intake values from the records and the questionnaire ranged from 0.14 (vitamin D, nonsig nificant, cod liver oil not included) to 0.66 (monounsaturated fatty a cids). The median coefficient was 0.52. Adjustment for energy intake d id not materially affect the correlations. On average 41% of the subje cts were classified in the same quartile in the questionnaire and the records, and 2% in the opposite quartiles. However, the percentage of subjects in the same/opposite quartiles for vitamin D and fibre were 3 3/12 and 22/6, respectively. Conclusions: It is concluded that the que stionnaire is able to rank subjects according to the tested nutrients, except vitamin D and fibre. Sponsorship: Ministry of Education, Resea rch and Church Affairs, Ministry of Children and Family Affairs, Minis try of Health and Social Affairs. Descriptors: adolescence, diet recor ds, epidemiological methods, nutrition surveys, questionnaires.