Development and application of a 2-step methodology to select a reference society providing Dietary Reference Values for national implementation

To describe and discuss a 2-step methodology developed to select a reference society that provides Dietary Reference Values (DRV) for national implementation and to illustrate its application in Switzerland with one macronutrient and one micronutrient. During Step 1, we searched and compared DRV and methodologies used to define DRV from eight European societies for seven selected nutrients. We repeated this procedure during Step 2 for DRV from two preselected societies for forty-four nutrients. The 2-step methodology applied here for Switzerland may be used in other countries. The research team commissioned six external experts from three linguistic regions of Switzerland, who provided their opinions through two online surveys, individual interviews and a focus group. After Step 1, we excluded five societies because of old publication dates, irrelevant publication languages for Switzerland, difficulty in accessing documents, or because their DRV were mainly based on another society. After Step 2, the two societies were qualified based on the analysis of the values and methodologies used. The need for free and easily accessible scientific background information favoured the European Food Safety Authority (EFSA). We chose alternative societies for nine nutrients for the overall population or subgroups and for the elderly. To manage heterogeneous and complex data from several societies, adopting a 2-step methodology including fewer nutrients and more societies during Step 1, and fewer societies but all nutrients in Step 2, was very helpful. With some exceptions, we selected EFSA as the main society to provide DRV for Switzerland.