Development of the Norwegian diet index and the Norwegian lifestyle index and evaluation in a national survey

Background: Dietary and lifestyle indices are composite tools that are used to estimate risk of health outcomes. Objective: We aimed to develop a diet and a lifestyle index assessing adherence to the national guidelines in Norway, and to investigate adherence in a nationwide survey of healthy subjects (Norkost3). Design: Cut-off values for the indices were based on the Norwegian food based dietary guidelines and national lifestyle guidelines. Adherence was evaluated in the Norkost3 (n = 1,787). Results: Twelve dietary components were included in the diet index 1) fruit and berries, 2) vegetables, 3) whole grains, 4) unsalted nuts, 5) fish, 6) low-fat dairy products, 7) margarine/oils, 8) red meat, 9) processed meat, 10) foods rich in sugar and fat, 11) drinks with added sugar, and 12) dietary supplements. Each of the components was assigned a value of 0, 0.5 or 1 corresponding to low, intermediate and high adherence, except for plant-based foods, which were assigned a value of 0, 1.5 or 3, providing a composite diet index ranging from 0 to 20 points. The five components in the lifestyle index (i.e. diet, body mass index (BMI), physical activity, tobacco and alcohol) was assigned a value of 0, 0.5 or 1, giving a final score ranging from zero to five points. In Norkost3, 49% (95% CI: 47, 52) of the participants had low adherence to the diet component, whereas only 2% (95% CI: 2, 3) achieved high adherence, although most of the subjects had high educational level. High adherence to the recommendations of BMI, tobacco and alcohol intake was observed in 50% (95% CI: 47, 52), 72% (95% CI: 70, 74) and 68% (95% CI: 66, 70) of the participants, respectively. Due to the lack of data on physical activity, adherence to this component in the lifestyle index is not presented in this study. Conclusion: The new diet and lifestyle indices assess adherence to the Norwegian food-based dietary guidelines (FBDGs) and other national lifestyle guidelines. In this study, half of the subjects had low diet and lifestyle index scores. There is a need to implement interventions to improve this by focusing on the specific lifestyle components with low adherence.