International research through epidemiological techniques has provided information on risk factors and preventive approaches in chronic disease. Causation complementing this base of knowledge with laboratory research on associated markers for each disease has outlined the possible mechanisms whereby risk factors and preventive conditions operate. Furthermore, laboratory research in animal models and cell cultures has expanded the appropriate elements associated with each condition. Individuals in the Mediterranean area present with a lower risk of several important chronic diseases, including coronary heart disease and a number of types of cancer associated with nutritional traditions, such as breast, colon, and prostate cancer. Vegetables and fruits in general and cooked tomatoes, together with olive oil, appear to be the nutritional traditions that account for this lower risk. These results lead to public health recommendations to consume more vegetables and, especially, cooked tomatoes with olive oil.