Several studies have reported that the Mediterranean diet slows cognitive decline and lowers risk of neurodegenerative diseases. While most of the research has been conducted in Mediterranean countries, consumption of the Mediterranean diet by other population groups have provided similar results.
A study on 2,000 New Yorkers who consumed the Mediterranean diet reported lower risk of Alzheimer’s disease; and another study on 1,410 elderly French individuals found slower cognitive decline with higher adherence to the Mediterranean diet. Last year, a review article called the Mediterranean diet a “model” diet for the prevention of Alzheimer’s disease.
While high intakes of cereals, vegetables, legumes, fruits and olive oil that make up the typical Mediterranean diet are recognized to be beneficial, a recent study found that long-term consumption of a Mediterranean diet supplemented with extra virgin olive oil or nuts had a positive impact on cognitive function in an older Spanish population. Phenolic compounds present in extra virgin olive oil and nuts may be the components responsible for this positive effect on cognition, according to the investigators of the study.
See Also: Olive Oil Health Benefits
In an article published in the March, 2015 issue of the journal Molecules, researchers specifically reviewed literature to explain how phenols present in extra virgin olive oil prevent neurodegenerative diseases.
According to the paper, olive oil contains about 230 chemical compounds of which carotenes and phenolic compounds are the main antioxidants. Of the phenols, hydroxytyrosol is the key phenolic compound present mainly in olives and olive products that are, in turn, the chief source of hydroxytyrosol in the Mediterranean diet.
Scientific evidence suggests that, as a potent antioxidant, hydroxytyrosol is not only effective in removing reactive oxygen species produced during oxidative stress, but it may also improve an organism’s defense against oxidative stress.
Oxidative stress, which produces more reactive oxygen species than the body can detoxify, may cause damage to the DNA and body proteins, and may be the origin of neurodegenerative diseases such as Alzheimer’s and Parkinson’s, as well as cancer, atherosclerosis, and diabetes.
Extensive research has identified hydroxytyrosol from olive oil to possess antioxidant, antimicrobial, and antidiabetic abilities. Additionally, hydroxytyrosol may provide protection against heart diseases and play a role in preventing or slowing the growth of tumors.
Research carried out in vitro and ex vivo to determine hydroxytyrosol’s role as a neuroprotective agent shows that hydroxytyrosol from olive oil protects cells from oxidative stress, improves resistance to oxidative stress, lowers incidence of brain cell death, and reduces neurotoxicity and DNA damage.
Furthermore, in some in vitro studies, hydroxytyrosol has been associated with the nuclear factor E2-related factor 2 (Nrf2) and Antioxidant Responsive Elements (ARE) neuroprotective pathways. The Nrf2 plays a positive role in regulating antioxidant response elements, which in turn regulate gene expression of several phase II detoxifying enzymes.
Supplementing the diet of mice with extra virgin olive oil and hydroxytyrosol enhanced cognitive function, and reversed oxidation, learning and memory damage. In another study, EVOO and hydroxtyrosol acted as brain antioxidants and provided protection against oxidative damage in mice with Huntington disease.
While in vitro and in vivo studies on animal models have linked hydroxytyrosol to improved health and cognition, there are very few studies on the effect of hydroxytyrosol in humans. So far, only three clinical trials on the role of hydroxytyrosol on breast cancer prevention; the effect of hydroxytyrosol supplements on multiple sclerosis; and its influence on phase II enzymes are underway.
Although more research is needed to establish the role of EVOO hydroxytyrosol in preventing neurodegenerative diseases, there is ample evidence that suggests that consuming a Mediterranean diet is beneficial for cognitive health.