Wikispanishfood editorial team
There are dozens of analyses on the benefits of olive oil, including PREDIMED.
PREDIMED is a long-term nutritional study entitled "Effects of the Mediterranean diet on the primary prevention of cardiovascular diseases."
It is a large-scale randomized nutritional intervention study on people with a high risk of cardiovascular disease. The main objective is to evaluate whether the Mediterranean diet supplemented with extra virgin olive oil and tree nuts prevents cardiovascular illnesses (cardiac death, heart attack and/or stroke) compared with a low-fat diet. The study also looks at secondary variables, evaluating the effects of the Mediterranean diet on overall mortality and the incidence of heart failure, diabetes, cancer, dementia and other neurodegenerative diseases.
The study has evaluated 7,447 people with high cardiovascular risk, who were divided into three groups at random and assigned the following eating regimens: Mediterranean diet supplemented with extra virgin olive oil, Mediterranean diet enriched with tree nuts (walnuts, hazelnuts and almonds), and a diet low in fat (both animal and vegetable). The participants met with a dietitian every three months and took part in informative group sessions at which they learned in detail about Mediterranean and low-fat diets. The study, the results of which were presented in 2013, yielded two important conclusions.
Reduction in Cardiovascular Risk
The PREDIMED study, coordinated by Ramon Estruch at Hospital Clínic in Barcelona, yielded scientific evidence that the Mediterranean diet reduces all cardiovascular disease risk factors.
At the end of the project, 30% of the participants who initially had risk factors (smoking, diabetes, high blood pressure) registered a reduction in risk, especially those that ate a diet supplemented with olive oil and nuts. However, among participants that only ate a low-fat diet, and who ended up eating a Mediterranean-style diet on their own, the incidence of serious problems was notably lower. This implies not only that extra virgin olive oil and nuts have protective properties, but that the Mediterranean diet in general has a positive effect on health. Cardiovascular mortality rates are lower in Mediterranean countries.
Prevention of dementia
A team headed by professor Miguel Ángel Martínez worked with a sample group of 522 people in Navarre who were monitored for six and a half years. The participants in the trial, aged 55 to 80, were randomly enrolled in the three abovementioned groups.
After six and a half years, people in the two Mediterranean diet groups had notably better cognitive function and mental performance, especially the group eating extra virgin olive oil, compared with the group assigned the low-fat diet.
This data confirms the results of several multiyear research projects on the effects of olive oil on health. According to the study, extra virgin olive oil contains oleocanthal, a molecule which plays a role in decreasing levels of amyloid beta (AB) proteins. Patients with Alzheimer's Disease have a build-up of AB in the brain; however, when extra virgin olive oil is consumed, oleocanthal helps remove those proteins. That is just one of the mechanisms for which olive oil is considered to be beneficial, as seen in this study.
The Mediterranean diet
The Mediterranean diet is characterized by a higher intake of extra virgin olive oil, fruit, vegetables, nuts, whole grains, legumes and fish, and limited consumption of meat and derivatives as well as dairy products. The diet is generally accompanied by moderate consumption of wine, mainly with meals (Source: Primary prevention of cardiovascular disease with a Mediterranean diet. Estruch R., Ros E., Salas-Salvadó J., et. al.).