The Mediterranean diet (MD) emerged as a healthy food regimen long before it could be recognised which nutrients or foods were responsible for its observed benefits, and it was only in the middle of the last century that the first scientific approach ‘The Seven Countries Study’ appeared. Epidemiological and anthropological studies of the MD converged, first by investigating at single nutrients or foods, then by adopting the more holistic approach of dietary patterns (DP), and now with a molecular approach. These studies resulted in convincing evidence that a MD decreases the risk of all-cause mortality and cardiovascular mortality and incidence. A risk reduction of developing type 2 diabetes is probable. Evidence is less stringent for other metabolic diseases and all cancers but from possible to probable for some cancer sites. Although DP showed that the MD has to be considered in its totality, olive oil could have a specific role. Lifestyle factors such as physical activity for energy balance, outdoor life for vitamin D synthesis and conviviality are also probably partly responsible for the health benefits. The MD is a lifestyle well suited for coping not only with personal health but also with wider societal concerns in relation to environment, public health and economy.

Objectives: Health services research is a typical instance of applied research, meaning that its research findings should contribute to a more evidence-based health policy. A basic assumption for the usefulness of policy research is that it is of good scientific quality, but evaluation of health services research would be incomplete without an assessment of its societal relevance. However, there is no generally accepted framework in which criteria to assess societal relevance are defined.

Methods: In this study, we made an effort to specify criteria and indicators for policy relevance.

Results and Conclusions: In general, we concluded that it is important to define from the start of a research project, what kind of answers are being sought to the questions at hand, who the intended users of these answers will be, and how they can be reached. Furthermore, a productive dialogue between researchers and policy makers is indispensable for remaining in tune with policy thinking. In addition, we specified domains and a list of potential criteria for assessing policy relevance. For the purpose of quality assurance, these criteria have to be integrated into a quality improvement cycle. This means that the societal output of health services research should be related to the aims and missions at the level of projects, programs, and institutes. Furthermore, it is important that consensus is reached about (the weighting of) relevant indicators and that routines are developed for collecting information on these indicators.