A study conducted by the Columbia University Medical Center examined the association between adherence to the Mediterranean diet and mild cognitive impairment (MCI) among 1393 multi-ethnic participants.  Using Cox proportional hazards, the association between adherence to the Mediterranean diet (0-9 scale) and the incidence of MCI, as well as the progression of MCI to Alzheimer’s disease was assessed.  The models were all adjusted for age, sex, ethnicity, education, genotype, caloric intake, body mass index, and duration between baseline dietary assessment and baseline dietary diagnosis.  The study concludes that a higher adherence to the Mediterranean diet correlates to a reduced risk of developing mild cognitive impairment and reduced risk of MCI conversion to Alzheimer’s disease.
Archives of Neurology 2009 Feb; 66(2):216-25 (Scarmeas et al.)
 

Oxidative DNA damage is one of the metabolic precursors to cancer and coronary vascular disease and phenols are organic compounds with antioxidant properties. A study conducted in Florence, Italy measured the oxidative DNA damage in ten healthy, post-menopausal women when they consumed olive oils with different concentrations of natural phenols. Subjects replaced fats and oils habitually consumed with the study oil (50g/d), which was either a high-phenol extra virgin olive oil (592 mg total phenols/kg) or a low-phenol extra virgin olive oil (147 mg total phenols/kg) for eight weeks in each period.  The study found that during treatment of high-phenol-EVOO, the average oxidative DNA damage was 30% lower than the average during low-phenol-EVOO treatment. Though the sample size was small, the study indicated that consuming an extra-virgin olive oil rich in phenols, particularly hydroxytryosol, may reduce DNA damage.
British Journal of Nutrition 2006 Apr; 95(4): 742-51 (Salvini et al.)