Observational epidemiological studies provide valuable information regarding naturally occurring protective factors observed in populations with very low prevalences of vascular disease. Between 1935 and 1965, the Italian-American inhabitants of Roseto (Pennsylvania, USA) observed a traditional Italian diet and maintained half the mortality rates from myocardial infarction compared with neighboring cities. In the Seven Countries Study, during 40years (1960–2000) Crete maintained the lowest overall mortality rates and coronary heart disease fatalities, which was attributed to strict adherence to the Mediterranean diet. In the French Three-City Study, a ten-year follow-up (2000–2010) showed that higher consumption of olive oil was associated with lower risk of death, as well as protection from cognitive decline and stroke. A large number of population-based studies and intervention trials have demonstrated that the Mediterranean diet is associated with lower prevalence of vascular disease, obesity, arthritis, cancer, and age-associated cognitive decline. Many of these effects are the result of consumption of fruits, seeds, legumes and vegetables but olive oil is the chief dietary fat in Mediterranean countries and the main source of monounsaturated fatty acids, as well as an important source of beneficial polyphenols and other antioxidants. Considering the critical role of vascular factors in the pathogenesis of late-onset Alzheimer disease it seems appropriate to focus on disease modification through proven dietary therapy. The authors base their hypothesis on meta-analyses of epidemiological data, numerous experimental studies, and a comprehensive review of the mechanisms of action of extra-virgin olive oil and its components in the prevention of vascular disease. In addition, extra-virgin olive oil has had positive effects on experimental animal models of Alzheimer disease. We therefore propose that extra-virgin olive oil is a promising tool for mitigating the effects of adverse vascular factors and may be utilized for potential prevention of late-onset Alzheimer disease.