Inhibition of circulating immune cell activation: a molecular antiinflammatory effect of the Mediterranean diet

Background: Adherence to the Mediterranean diet (Med-Diet) is associated with a reduced risk of cardiovascular disease (CVD). However, the molecular mechanisms involved are not fully understood. Objective: The objective was to compare the effects of 2 Med-Diets with those of a low-fat diet on immune cell activation and soluble inflammatory biomarkers related to atherogenesis in subjects at high risk of CVD. Design: In a controlled study, we randomly assigned 112 older subjects with diabetes or >= 3 CVD risk factors to 3 dietary intervention groups: Med-Diet with supplemental virgin olive oil (VOO), Med-Diet with supplemental nuts, and low-fat diet. Changes from baseline in cellular and serum inflammatory biomarkers were assessed at 3 mo. Results: One hundred six participants (43% women; average age: 68 y) completed the study. At 3 mo, monocyte expression of CD49d, an adhesion molecule crucial for leukocyte homing, and of CD40, a proinflammatory ligand, decreased (P < 0.05) after both Med-Diets but not after the low-fat diet. Serum interleukin-6 and soluble intercellular adhesion molecule-1, inflammatory mediators crucial in firm adhesion of leukocytes to endothelial surfaces, decreased (P, 0.05) in both Med-Diet groups. Soluble vascular cellular adhesion molecule-1 and C-reactive protein decreased only after the Med-Diet with VOO (P < 0.05), whereas interleukin-6, soluble vascular cellular adhesion molecule-1, and soluble intercellular adhesion molecule-1 increased (P < 0.05) after the low-fat diet. Conclusions: Med-Diets supplemented with VOO or nuts down-regulate cellular and circulating inflammatory biomarkers related to atherogenesis in subjects at high risk of CVD. The results support the recommendation of the Med-Diet as a useful tool against CVD. Am J Clin Nutr 2009; 89: 248-56.