Development and evaluation of an index assessing adherence to the Norwegian food-based dietary guidelines: the Norwegian Dietary Guideline Index (NDGI).

backgroundMonitoring adherence to the Norwegian food-based dietary guidelines (FBDGs) could provide valuable insight into current and future diet-related health risks. This study aimed to develop and evaluate an index measuring adherence to the Norwegian FBDGs to be used as a compact tool in nutrition surveillance suitable for inclusion in large public health surveys.

methodsThe Norwegian Dietary Guideline Index (NDGI) was designed to reflect adherence to the Norwegian FBDGs on a scale from 0-100, with a higher score indicating better adherence. Dietary intakes were assessed through 19 questions, reflecting 15 dietary components covered by the Norwegian FBDGs. The NDGI was applied and evaluated using nationally representative dietary data from the cross-sectional web-based Norwegian Public Health Survey which included 8,558 adults.​

resultsThe population-weighted NDGI score followed a nearly normal distribution with a mean of 65 (SD 11) and range 21-99. Mean scores varied with background factors known to be associated with adherence to a healthy diet; women scored higher than men (67 vs. 64) and the score increased with age, with higher educational attainment (high 69 vs. low 64) and with better self-perceived household economy (good 67 vs. restricted 62). The NDGI captured a variety of dietary patterns that contributed to a healthy diet consistent with the FBDGs.

conclusionThe NDGI serve as a compact tool to assess and monitor adherence to the Norwegian FBDGs, to identify target groups for interventions, and to inform priorities in public health policies.​ The tool is flexible to adjustments and may be adaptable to use in other countries or settings with similar dietary guidelines.