There is mounting evidence demonstrating the positive impact of olive oil on conditions involving cognitive deficits, such as mild cognitive impairment (MCI) and Alzheimer's disease.
Obtained by pressing fresh olives, olive oil has been hailed for its nutritional and health benefits since ancient Mediterranean times.
Famously described in ancient times by Homer as 'liquid gold', olive oil has been known throughout time to be high in antioxidants and of great medicinal value.
Olive oil is a central and distinguishing component of the Mediterranean diet, one of the healthiest diets around.
In recent years, researchers have been exploring olive oil's potential to help prevent and treat various illnesses including cognitive disorders, also known as neurocognitive disorders - a category of mental health disorders that primarily affect cognitive abilities such as learning, memory, perception, and problem-solving.
Despite this, on 7 June this year, the U.S. Food and Drug Administration (FDA) approved a controversial drug that may slow cognitive decline in patients in the early stages of Alzheimer's.
Neurologist Allan Levey, MD, PhD, director of Emory University's Goizueta Alzheimer Disease Research Center, was blunt in his assessment of aducanumab, sold under the brand name Aduhelm and marketed by Biogen, based in Cambridge, Massachusetts, and Eisai, headquartered in Tokyo.
"I would not have approved it," Levey, who is not a member of the FDA advisory committee that reviewed aducanumab, said in an interview. "I think the scientific question of whether it works is still open."
Uncertainty about the drug's efficacy and cost and concern about the possibility of severe side effects led three FDA advisory committee members to resign.
All the while, studies worldwide show that a natural compound, none other than extra virgin olive oil, provides high protection over cognitive function and can potentially achieve better results than existing manufactured drugs in the prevention and treatment of cognitive impairment.
Most recently, the six-year MICOIL study was the first in the world to test extra virgin olive oil (EVOO) in a clinical trial in humans with mild cognitive impairment (MCI).
The objective of the study was to investigate for the first time the effect of Greek High Phenolic Early Harvest Extra Virgin Olive Oil (HP-EH-EVOO) versus Moderate Phenolic (MP-EVOO) and Mediterranean Diet (MeDi) in people with mild cognitive impairment (MCI).
The beneficial effects of olive oil are primarily attributed to some phenolic compounds derived from olive oil, such as oleocanthal, oleuropein and ligstroside.
Oleocanthal has been researched more extensively than the remaining olive oil phenol components, showing promising results in neuroprotection against Alzheimer's through various suggested mechanisms, such as the enhancement of amyloid-beta clearance in the brain and the inhibition of neurofibrillary tangles formation.
For this reason, the researchers of the MICOIL study sought to examine the effects of freshly-pressed extra virgin olive oil, as it is known that it contains oleocanthal in higher concentrations than the regular extra virgin olive oil.
The MICOIL study divided the sample participants randomly into three groups. Group 1 received 50 mL per day of High Phenolic Early Harvest Extra Virgin Olive Oil (HP-EVOO). Group 2 received 50mL per day of Moderate Phenolic (MP-EVOO), and Group 3 received only the Mediterranean diet instructions for the test period.
Genetic predisposition (APOEɛ4) to Alzheimer's disease was tested, and an extensive neuropsychological battery (series of tests) administered prior to the study commencing, and again after 12 months to assess cognitive domains including attention, language, memory, spatial and executive functions.
After the 12 months, better follow-up performance was found in Group 1 compared to Group 2 and Group 3 in almost all cognitive domains.
Group 1 showed significantly improved cognitive scores compared to Group 2 in ADAS-cog (the Alzheimer's Disease Assessment Scale–Cognitive Subscale developed in the 1980s to assess the level of cognitive dysfunction in Alzheimer's disease) as well as MMSE (the Mini Mental State Examination, the most commonly used test for memory and other mental abilities). In contrast, Group 3 exhibited worse or similar to baseline performance across all cognitive domains.
Moreover, there was a significant difference in the presence of proteins in the blood that indicate the presence of Alzheimer's (APOEɛ4) between Groups 1 and 2 versus Group 3. The MCI patients who consumed 50mL of EVOO per day for a year had significantly decreased levels of the APOEɛ4.
As a result, the MCOIL study concluded that a long-term diet rich in EVOO can help protect against mild cognitive impairment and Alzheimer's disease.
In addition, the research also demonstrated that consumption of EVOO with moderate to high amounts of the natural plant compounds called phenols could provide even more benefits than low-phenolic olive oil.
Additional research has shown that the benefits of taking high phenolic olive oil is dose-dependent with the higher the concentration of phenolic compounds, the greater the potential health benefit.
Most human research trials showing the effectiveness of high phenolic EVOO on illnesses such as Alzheimer's have used olive oils of around 800 mg/kg, with the highest ratio of phenolic compounds being oleocanthal and oleacein.
As well as protecting against mild cognitive impairment and Alzheimer's disease, olive oil has also been identified as playing a successful role in the prevention of other chronic illnesses such as cardiovascular disease, diabetes and cancer.
So as proclaimed by Hippocrates, the father of medicine, 2,500 years ago: 'Let food be your medicine, and medicine be your food.'