The research has been based on a plethora of observational epidemiological studies, local population experiences, meta-analyses of epidemiologic data, and experimental studies, all converging to the connection between the Mediterranean diet and a reduced prevalence of different ailments. The study scopes extend over long periods, such as the Italian-American experience from 1935 to 1965, or the Seven Countries Study spanning four decades from 1960 to 2000. Another significant evidence base is the French Three-City Study, which followed participants for ten years from 2000 to 2010. Apart from human trials, the article includes results from experimental animal models, specifically concerning late-onset Alzheimer disease.

The findings showcase a consistent trend linking reduction in vascular diseases, obesity, arthritis, cancer, cognitive decline, and specifically Alzheimer's disease with increased adherence to a Mediterranean dietary pattern, particularly high intake of extra-virgin olive oil. Certain dietary components such as fruits, seeds, legumes, and vegetables contribute to the benefits. However, olive oil stands out as the chief dietary fat in Mediterranean countries. It provides plentiful monounsaturated fatty acids, beneficial polyphenols, and other antioxidants, which play a crucial part in these health benefits. The most striking discovery is extra-virgin olive oil's potential to mitigate the effects of adverse vascular factors, indicating a promising approach to preventing late-onset Alzheimer's disease.