Does Mediterranean diet have a positive influence on microvascular function ? Evidence and doubts.

The Mediterranean is a vast area characterized by populations and countries with different culture, economy and agricultural production. Diet habits vary significantly between these countries but a peculiar and common pattern is represented by a high consumption of fruit, vegetables and low intake of meat and saturated fats. The preference for fresh fruit and vegetables results in high consumption of raw foods and contributes to a reduced production of cooking-derived carcinogens and oxidants. Popularized by Ancel Keys in 1975, the Mediterranean diet (MD) has been associated with a significant improvement in health status and with a significant reduction in coronary heart disease, cancer, and overall mortality. The benefits of the MD are mainly ascribed to its high antioxidant potential and to the richness in flavonoids and other polyphenols contained in food and beverages. These substances are reducing agents and along other dietary macro- and micronutrients may protect tissues against oxidative stress, thus preventing cellular oxidative reactions and scavenging reactive oxygen species. Consequently, antioxidant properties of typical Mediterranean foods (olive oil, herbs, fruits and vegetables, wine) might limit the development and the progression of oxidative stress-associated diseases. In particular, it has been suggested that the protective effect of MD on cardiovascular system may be ascribed to a variety of antioxidant-mediated mechanisms including a substantial improvement of endothelial function and blood lipid profile, a higher resistance to in vitro copper-mediated oxidation of LDL-cholesterol as well as a positive modulation of cytokines and eicosanoids involved in the inflammatory response. Many investigations have also identified a possible effect of MD in reducing blood platelet’s responsiveness, mainly adhesion and aggregation, via different mechanisms usually maintained by the antioxidant activity of MD components. Although results of studies in vitro disclose the potential mechanisms of the Mediterranean diet in disease prevention and epidemiological findings suggest the clinical relevance for public health of a strict adherence to MD, no controlled studies are carried out to evaluate the effects on MD nutrient components of modern intensive agriculture and of the present methods of technology for food preservation, processing, transport and marketing, particularly throughout the less developed and marginal regions of the world. Furthermore it is alarming that modern society appears to abandon the traditional diet and this is indicative of the need for new approaches in transmitting the MD pattern.