We examined associations between two Mediterranean diet (MD) adherence indexes (the MD index, MDI, and the MD score, MDS) and several blood biomarkers of diet and disease.

We studied 328 individuals from Catalonia (Northeastern Spain), ages 18–75, who provided fasting blood samples, a subset of the 2346 individuals as part of a larger representative and random sample from the 1992–1993 Catalan Nutritional Survey.

Diet was measured using 24-h recalls. Biomarkers studied were plasma levels of β-carotene, α-tocopherol, retinol, vitamins B12, C and folates as well as serum total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides. Multivariate linear regression was used to analyse associations of the nutrient biomarkers with the dietary pattern indexes, adjusting for potential confounders.

Subjects with higher MD adherence, as measured by the two dietary indexes, had significantly higher plasma concentrations of β-carotene, folates, vitamin C, α-tocopherol and HDL cholesterol. The most highly significant relationship was that between folates and the adherence to the MD Pattern, as determined by both indexes.

These research findings suggest the potential usefulness of biomarkers as complementary tools for assessing adherence to a dietary pattern. This type of data not only informs the development of robust dietary adherence indexes, but it also provides specific clues about the potential physiological mechanisms that explain the beneficial effects of the MD pattern on chronic disease risk.