A blood biomarker score that can help measure an individual's adherence to the so-called Mediterranean diet is reported in PLOS Medicine this week, providing a tool that could be used to evaluate links between the diet and the risk of diseases such as type 2 diabetes. The Mediterranean diet — which is characterized by high consumption of fruits, vegetables, grains, fish, and olive oil, with moderate intake of red meat, dairy, and wine — has been associated with a decreased incidence of type 2 diabetes. But because adherence to this diet is largely self-reported, there is uncertainty about the validity and magnitude of this association. To address this, a group led by University of Cambridge researchers developed a biomarker score of a Mediterranean diet based on certain blood carotenoids and fatty acids that were previously shown to reflect adherence to the diet in a clinical study. They then applied the biomarker score in a large observational study, which included more than 22,000 participants in eight European nations, to assess its association with type 2 diabetes incidence over a nearly 10-year period. When comparing the roughly 9,500 participants who developed type 2 diabetes with the nearly 12,800 who didn't, the investigators confirmed that those whose biomarker score indicated a greater adherence to the Mediterranean diet were less likely to develop the disease. Notably, the findings indicate that even modestly higher adherence to the Mediterranean diet can cut type 2 diabetes risk, adding to the evidence supporting the benefits of the diet to Western European adults.