People who consume at least half a tablespoon of extra virgin olive oil daily have a 28% lower risk of dying from dementia-related causes, the seventh highest cause of death world-wide.
Findings from a 28-year study amongst more than 92 000 American adults by Harvard Medical School suggest that olive oil represents a potential strategy to reduce the risk of mortality due to dementia.
The Harvard study, published in 2024:
A higher olive oil intake is associated with a lower risk of cardiovascular disease and mortality, but its association with dementia-related mortality was previously unknown. As olive oil is rich in monounsaturated fats and contains compounds with antioxidant activity, it was suspected to play a protective role in the brain.
The Harvard study extracted data from two American studies, the Nurses’ Health Study (1990-2018) and the Health Professionals Follow-up Study (1990-2018). 92 383 participants were free of cardiovascular disease and cancer when the studies commenced. The study attempted to identify possible links between olive oil consumption and the risk of dementia-related mortality.
A food frequency questionnaire every 4 years monitored diet and olive oil consumption. Deaths due to dementia as the underlying cause of death, or as a contributing cause of death, was ascertained from death records during the length of the study.
Main findings of the Harvard study:
- Consuming at least 7 grams of extra virgin olive oil daily (half a tablespoon) was associated with a 28% lower risk of dementia-related death, compared with participants who rarely or never consumed olive oil.
- Interestingly, this is irrespective of the diet followed by the participants, which suggests specific olive oil benefits.
- Replacing 5 gram (one teaspoon) per day of mayonnaise with the same amount of olive oil was associated with a 14% lower risk of dementia-related mortality. (At the time of the study, mayonnaise contained significant levels of hydrogenated trans-fats.)
- Replacing 5 gram per day of margarine with the equivalent amount of olive oil resulted in an estimated 8% lower risk of dementia-related death. (At the time of the study, margarine contained significant levels of hydrogenated trans-fats.)
- Although substituting other vegetable oils or butter with olive oil were not statistically significant in terms of dementia-related mortality, substitution with olive oil is associated with a lower risk of type 2 diabetes, cardiovascular disease, and total mortality.
- Participants who inherited a risk gene tied to Alzheimer’s disease from both parents, were five to nine times more likely to die from dementia.
Main markers of Alzheimer’s disease:
There is currently no medicine (drug) available to prevent, slow down, or cure the cognitive decline that is associated with dementia, of which Alzheimer’s disease is the most common form.
Alzheimer’s disease gradually robs its victims of their humanity with the loss of memory, capacity for thought, and the ability to live full and independent lives, resulting in an unrelenting descent into an abyss of mental fog.
Alzheimer’s disease is a progressive neurogenerative brain disorder which, amongst other causes, is characterized by several key pathological markers:
- Deposition of amyloid plaques. The fatty membrane that surrounds brain cells contain a protein molecule called beta-amyloid, which can cause plaque build-up outside the cells of the brain when it clumps together. These sticky globs of amyloid can gung up the spaces (the synapses) between brain cells (neurons). As neurons communicate with each other via the synapses, the damage caused by the plaque can have devastating consequences for the transfer of signals (communication) between neurons. This can ultimately kill neurons.
- Neurofibrillary tangles. Tau is a normal protein that transports nutrients into brain cells and move waste products out of brain cells. Aging, or errant genes, can cause tau to become abnormal, resulting in pieces of the tau protein to tangle and clump together. These neurofibrillary tangles are bundles of filaments composed primarily of tau protein, which often first form in the regions in the brain that is used for memory, but can soon spread across the rest of the brain. In this event the nutrients and toxic waste products can no longer move freely in or out of brain cells and affected cells may eventually die.
- Neuroinflammation. Neuroinflammation refers to inflammation of the nervous tissue within the brain or spinal cord. Alzheimer’s disease is characterized by sustained neuroinflammation, leading to memory loss and cognitive decline. The chronic neuroinflammation is primarily driven by the immune system’s inflammatory response, in trying to protect the brain from damage.
- Blood-brain barrier dysfunction. A primary protective boundary exists between the blood microcirculation system and the functional tissue in the brain (made up of neurons and glial brain cells) as an active exchange platform to transport molecules between the blood and the extracellular fluid of the central nervous system and is aptly called the blood-brain barrier. The blood-brain barrier effectively protects brain tissue from circulating pathogens and other potentially toxic substances. Dysfunction of the blood-brain barrier makes it permeable, allowing entry of toxic substances to the brain.
- Increased oxidative stress. Oxidative stress occurs when there are too many unstable molecules called free radicals in the body and not enough antioxidants to get rid of them, which can lead to cell damage, including neuronal (brain cell) damage, contributing to Alzheimer’s disease.
- Autophagy dysfunction. Autophagy is described as the body’s cellular recycling system, disassembling the litter (junk parts), while repurposing the salvageable parts into new and usable cell parts. As too many junk parts can take up too much space in the cell and affect its functioning, autophagy helps the cell to discard the parts it doesn’t need. It also converts the clutter into components the cell can use, which optimizes the cell’s performance. Dysfunctional autophagy is closely linked to Alzheimer’s disease.
Studies on extra virgin olive oil in Alzheimer’s disease:
As currently available medications only offer symptomatic relief, but fail to provide a cure or halt the progression of Alzheimer’s disease, the focus of research has shifted towards prevention rather than treatment.
Studies have highlighted the remarkable impact of the Mediterranean diet to decrease the risk of cognitive decline and dementia. Central to the Mediterranean diet’s neuroprotective arsenal is extra virgin olive oil, a substantial portion of the daily dietary fat intake and a source of over 100 phenolic compounds (natural bioactive molecules). As these phenolic compounds have anti-inflammatory, antioxidant, and neuroprotective properties, they are increasingly receiving attention for their potential role in preserving cognitive function and in combatting Alzheimer’s disease.
Laboratory experiments, animal studies, and human trials suggest that the more than 100 phenolic compounds in extra virgin olive oil may have potential influences on the key pathological hallmarks of Alzheimer’s disease, with some of the key actions described here in very simplistic terms:
- Deposition of amyloid plaques. These phenolic compounds may modulate the formation and accumulation of amyloid plaques and may potentially enhance their clearance from the brain.
- Neurofibrillary tangles. Phenolic compounds may also modulate the formation and accumulation of tau protein tangles and mitigate the associated disruptions in neuronal communication.
- Neuroinflammation. As the advent of amyloid plaques and tau protein tangles triggers the immune system as the brain tries to protect itself, resulting in chronic neuroinflammation, any reduction in or slowing down in the forming of plaques and tangles in the brain would result in reduced neuroinflammation.
- Blood-brain barrier dysfunction. The role of extra virgin olive oil extends to assisting with maintaining the integrity of the blood-brain barrier, as it potentially strengthens its selective permeability while limiting the infiltration of neurotoxic substances.
- Increased oxidative stress. The rich array of antioxidants in extra virgin olive oil may help to counteract the oxidative stress that is a characteristic of Alzheimer’s disease.
- Autophagy dysfunction. By playing a role in autophagy, extra virgin olive oil and its compounds may contribute to the upregulating of autophagy.
Scientists are suggesting that extra virgin olive oil and its phenolic compounds collectively have potential as part of a dietary strategy to manage or prevent Alzheimer’s disease.
A number of in-vitro (laboratory) and in in-vivo (animal) studies, which evaluated the effects of certain individual olive oil compounds, resulted in some significant findings, of which a few key ones are listed:
- Upregulated antioxidant enzymes.
- Reduced cell damage and mitochondrial impairment.
- Reduced oxidative damage.
- Reduced apoptosis (cell death).
- Reduced neurotoxic effects.
- Reduced neuroinflammation.
- Reduced amyloid plaque and tau tangle levels, with increased clearance of amyloid plaque.
- Enhanced autophagy.
- Restored blood-brain barrier function.
- Improved memory.
A number of clinical studies in humans indicated that a high adherence to the Mediterranean diet showed a 33% lower risk of cognitive impairment and results further indicate that consuming extra virgin olive oil as part of the Mediterranean diet could reduce the risk of dementia or slow the conversion of mild cognitive impairment to Alzheimer’s disease.

Conclusion:
The promising outcomes of pilot studies as well as the Harvard study highlight the significance of extra virgin olive oil and its phenolic compounds. This warrants its consideration as a medical food in dietary guidelines for those at risk of neurogenerative diseases.
Current scientifically based evidence suggests that we should be limiting saturated fats (which are solid at room temperature) and more frequently incorporate olive oil and other unsaturated oils (liquid at room temperature), also opting for a comprehensively healthy diet (such as the Mediterranean, MIND, or DASH diets), engage in regular exercise, and stay socially and cognitively engaged to maximize cognitive health and reduce the risk of dementia.
The Harvard study highlighted the importance of consuming at least half a tablespoon of extra virgin olive oil daily. When buying olive oil, be sure to look out for “extra virgin, cold pressed” olive oil and ensure it is fresh by checking the bottling date. As heat and light are the enemies that lead to oxidation of the olive oil, it should be bottled in a dark tinted glass bottle and stored in a dark cupboard. Another hint when buying olive oil is to take a bottle from the very back of the shelf they are stored on, as they are shielded from light at the back.
References:
How olive oil can help you to avoid Alzheimer’s. Blog published 8 August 2024. Dr David Perlmutter, neurologist and author. (www.drperlmutter.com)
Olive oil may reduce risk of death from dementia. Published 14 May 2024. Harvard School of Public Health. Harvard Medical School. (www.hsph.harvard.com)
Consumption of olive oil and diet quality and risk of dementia-related deaths. Published 6 May 2024, JAMA Network Open 2024; 7(5): e 2410021. (www.jamanetwork.com)
Olive oil could reduce risk of dying from dementia, Harvard study says. Published 6 May 2024. United Press International. (ww.upi.com)
Extra virgin olive oil in Alzheimer’s disease: a comprehensive review of cellular, animal, and clinical studies. Published February 2024 in International Journal of Molecular Sciences. National Centre for Biotechnology Information. US National Library for Medicine. National Institutes of Health. USA. (www.ncbi.nlm.nih.gov)
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