Olive oil compounds as a potential therapy for Neurodegeneration

The Mediterranean diet has long been touted for its ability to decrease one’s risk of suffering from health problems such as diabetes, cardiovascular disease, certain types of cancer, and neurodegenerative diseases. Although various studies support these claims, it isn’t always clear how the Mediterranean diet confers these benefits. While olive oil isn’t the only component in the Mediterranean diet, research suggests that it may be a crucial factor contributing to the diet’s favorable reputation. More specifically, polar compounds in olive oil called phenols could potentially prevent neurodegeneration and therefore act as a potential treatment for neurodegenerative diseases.

Phenols are aromatic or ring-containing organic compounds with a hydroxyl -OH group attached to at least one of the carbons in the ring. One phenol in olive oil called hydroxytyrosol seems to be the main compound responsible for olive oil’s neuroprotective potential due to its antioxidant properties and interaction with pathways that manage oxidative stress. As an antioxidant, hydroxytyrosol donates a hydrogen atom from one of its hydroxyl groups to stabilize free radicals, which are unstable molecules with an unpaired electron in their orbital. When a free radical pairs with the donated hydrogen, its unpaired electron pairs with the hydrogen’s electron, ultimately becoming stable and less likely to damage other molecules. One of the pathways with which hydroxytyrosol is thought to interact is the Keap1/Nrf2/ARE pathway. This pathway regulates the expression of phase II detoxification enzymes that defend against harmful chemicals like carcinogens and free radicals.

It is important that hydroxytyrosol plays a role in antioxidation because neurodegenerative diseases are often characterized by oxidative stress which is caused by an imbalance between oxygen-derived radicals and antioxidants in the brain.

It is important that hydroxytyrosol plays a role in antioxidation because neurodegenerative diseases are often characterized by oxidative stress which is caused by an imbalance between oxygen-derived radicals and antioxidants in the brain. Consequently, any substance that acts as an antioxidant or increases the concentration of enzymes that assist in neutralizing free radicals could be a beneficial therapy to treat neurodegenerative diseases. Other factors to consider include how well the substance is absorbed by the body, how it interacts with other systems of the body, its ability to cross the blood-brain barrier, and its bioavailability. According to a review in Molecules, hydroxytyrosol is well-absorbed and able to cross the blood-brain barrier, but the chemical also undergoes processing in the small intestine and liver before entering the bloodstream, resulting in poor bioavailability. However, poor bioavailability doesn’t necessarily mean that hydroxytyrosol is a poor therapeutic candidate. Instead, it means that more research should be conducted with higher concentrations of hydroxytyrosol as well as in vivo in humans to gain a better understanding of how hydroxytyrosol functions.

Any substance that acts as an antioxidant or increases the concentration of enzymes that assist in neutralizing free radicals could be a beneficial therapy to treat neurodegenerative diseases.

If olive oil contains hydroxytyrosol, how does olive oil impact neurodegeneration? Unfortunately, consuming high amounts of olive oil daily is unlikely to have a large impact in preventing neurodegeneration. One issue is that most olive oils don’t have sufficient concentrations of hydroxytyrosol. The European Food and Safety Authority set a minimum daily requirement of five milligrams of hydroxytyrosol for beneficial effects to occur, but the median concentration of hydroxytyrosol in olive oil is 1.9 mg/kg, which isn’t nearly enough for people to reach the minimum daily requirement. However, the International Olive Council is currently evaluating methods to accurately estimate the concentration of hydroxytyrosol in olive oils, which could be useful if oil producers decide to prepare hydroxytyrosol-enriched olive oils. The other issue, as previously mentioned, is hydroxytyrosol’s poor bioavailability once consumed. If olive oil doesn’t have high concentrations of hydroxytyrosol, it is highly unlikely that a significant amount of hydroxytyrosol would be usable anyway.

Extra virgin olive oil — relative to coconut oil and butter — improved learning and memory in an early-learning and memory decline mouse model

Despite evidence that olive oil currently doesn’t have enough hydroxytyrosol for people, studies have analyzed the neuroprotective effects of olive oil in mice. One study published in the Journal of Alzheimer’s Disease found that extra virgin olive oil — relative to coconut oil and butter — improved learning and memory in an early-learning and memory decline mouse model known as SAMP8. While it is unknown whether studies like this will translate to humans, there is still potential for hydroxytyrosol to be a therapy for neurodegenerative diseases and for producers to create hydroxytyrosol-enriched olive oil or other hydroxytyrosol-enriched products.

Molecules (2015). DOI: 10.3390/molecules20034655

Mechanisms of Aging and Development (2022). DOI: 10.1016/j.mad.2022.111637

Encyclopedia of Cancer (2011). DOI: 10.1007/978-3-642-16483-5_4510

Journal of Alzheimer’s Disease (2012). DOI: 10.3233/JAD-2011-110662