Extra Virgin Olive Oil Linked to Better Brain Function — And Your Gut May Be the Reason Why

A new human study has found that people who regularly consume extra virgin olive oil instead of refined olive oil show measurable improvements in cognitive performance and harbour a more diverse population of gut bacteria.

Published in January 2026 in the journal Microbiome, the research tracked 656 adults over two years and is described by its authors as the first prospective study in humans to specifically examine how olive oil influences the interaction between the gut microbiota and cognitive function.

The key finding is straightforward: the type of olive oil you use matters, and the difference between extra virgin and refined may show up not just in your digestion, but in your brain.

This is not the first time olive oil has been tied to brain health.

A landmark 2024 Harvard study tracking more than 92,000 American adults over 28 years found that consuming at least 7 grams of olive oil per day was linked to a 28% lower risk of dementia-related death, regardless of overall diet quality or genetic risk.

But that study did not distinguish between olive oil types.

This new research does, and the difference is striking.

What the Study Actually Found

The research team, led by scientists from the Human Nutrition Unit at the Universitat Rovira i Virgili (URV) in Spain, drew on data collected over two years through the PREDIMED-Plus project, one of Europe’s largest ongoing nutrition and cardiovascular health studies.

Participants were adults aged 55 to 75, all of whom were overweight or obese and had metabolic syndrome, a cluster of conditions including high blood pressure, elevated blood sugar, and excess belly fat that significantly raises cardiovascular and cognitive risk.

Researchers examined what types of olive oil participants were consuming, tested the composition of their gut bacteria, and tracked changes in cognitive performance throughout the follow-up period.

The results pointed clearly in one direction.

People who regularly consumed virgin olive oil showed improvements in cognitive scores and had greater diversity in their gut microbiota.

Those who consumed refined olive oil showed a decline in microbial diversity over time.

The researchers also identified a specific bacterial genus, Adlercreutzia, which appeared in higher levels among participants who consumed virgin olive oil and who showed better cognitive outcomes.

This bacterium may act as a biological marker, and potentially a mediator, of the brain-protective effects of extra virgin olive oil.

Why This Study Is Different

Plenty of research has explored the Mediterranean diet and brain health in general terms.

What makes this study stand out is that it looked specifically at olive oil type, isolated it as a variable, and followed real people over two years rather than relying on short-term lab experiments.

It also connected three dots that had rarely been examined together in a single human cohort: diet, gut microbiome composition, and cognitive function.

As lead author Jiaqi Ni explained, “This is the first prospective study in humans to specifically analyze the role of olive oil in the interaction between gut microbiota and cognitive function.”

That matters because most of what we previously knew about olive oil and the gut-brain axis came from animal studies or cell experiments, not real-world human data collected over time.

The Gut-Brain Axis: The Missing Link

To understand why olive oil can influence the brain through the gut, you need to understand what the gut-brain axis actually is.

The gut and the brain are in constant communication through a two-way signalling network that scientists call the gut-brain axis.

According to research published in the journal Frontiers in Neuroanatomy, this axis connects the central nervous system with the enteric nervous system, often called the “second brain,” through neural, immune, and hormonal pathways.

The primary highway for this communication is the vagus nerve, a long nerve that runs from the brainstem all the way down into the abdomen.

Gut bacteria produce metabolites, including short-chain fatty acids, that travel through the bloodstream and influence brain function directly.

They also interact with the immune system, helping to regulate inflammation throughout the body, including in the brain.

When gut microbial diversity is high and the balance of bacteria is healthy, this communication system tends to function well.

When diversity drops, or when harmful bacteria dominate, the signals that reach the brain can promote inflammation, impair memory, and accelerate cognitive decline.

A review published in Physiological Reviews describes the gut-brain axis as a key regulator of psychiatric, neurodevelopmental, and neurodegenerative disorders.

The PREDIMED-Plus study suggests that extra virgin olive oil may be one of the most accessible tools available for keeping that axis in good shape.

Extra Virgin vs. Refined: What Is the Actual Difference?

Many people assume all olive oil is basically the same.

The label “olive oil” on a supermarket shelf covers a wide range of products, and the differences between them are substantial.

Extra virgin olive oil is produced using only mechanical methods, meaning the oil is simply pressed from the olives without heat or chemical solvents.

This minimal processing preserves the naturally occurring compounds in the fruit, including polyphenols, antioxidants, vitamin E, and other bioactive substances that are believed to drive most of the health benefits.

Refined olive oil, by contrast, goes through an industrial process designed to remove impurities, correct defects in flavour, and extend shelf life.

That process strips away many of the bioactive compounds.

The resulting oil may look and cook similarly to extra virgin, but it lacks the polyphenol content that researchers believe is responsible for the gut and cognitive benefits.

As study author Jiaqi Ni noted, “not all olive oils have benefits for cognitive function,” and the recommendation from the research team is clear: choose extra virgin.

Polyphenols: The Active Ingredient for Your Brain

The compounds that differentiate extra virgin olive oil are not random.

Polyphenols are plant chemicals that act as powerful antioxidants and anti-inflammatory agents.

In olive oil, the key polyphenols include oleocanthal, oleuropein, and hydroxytyrosol, all of which have been studied for their neuroprotective properties.

Research published in Nutrients in 2022 showed that olive oil polyphenols can cross the blood-brain barrier directly, potentially protecting neurons from oxidative stress and reducing the inflammation associated with neurodegenerative diseases like Alzheimer’s.

Oleocanthal, in particular, has drawn attention for its ability to mimic the anti-inflammatory action of ibuprofen at a molecular level.

Chronic low-grade inflammation in the brain is increasingly recognised as a driver of cognitive decline, and polyphenols may help keep that inflammation in check.

Beyond direct neuroprotection, polyphenols also feed the beneficial bacteria in the gut.

They act as prebiotics, nourishing microbes that in turn produce metabolites beneficial to brain function.

This is likely one of the key mechanisms through which extra virgin olive oil supports both gut diversity and cognitive performance simultaneously.

The Adlercreutzia Connection

One of the most specific and intriguing findings in the PREDIMED-Plus study was the identification of Adlercreutzia as a potentially important microbial link.

This bacterial genus is not widely known outside of microbiome research, but it is associated with the metabolism of plant-based compounds, including polyphenols.

The fact that higher levels of Adlercreutzia were found in participants consuming virgin olive oil, and that these same participants showed better cognitive outcomes, suggests a possible chain of events.

Extra virgin olive oil delivers polyphenols to the gut.

Those polyphenols support the growth of bacteria like Adlercreutzia.

Those bacteria produce metabolites that benefit the brain.

This is still a proposed mechanism rather than a proven pathway, and more research will be needed to confirm the exact role of this bacterium.

But the finding adds a layer of biological plausibility to the link between olive oil type and brain health.

Why This Matters Right Now

The stakes of this research are high, and they are only getting higher.

According to the World Health Organization, approximately 55 million people worldwide are currently living with dementia, and that number is projected to nearly triple by 2050 as populations age.

The Lancet Public Health estimates that global dementia cases could rise from 57 million in 2019 to 153 million in 2050, driven primarily by population growth and ageing.

Currently, there are no drugs that can stop or reverse the progression of most forms of dementia.

That is exactly why dietary strategies draw so much attention from researchers.

A safe, accessible, affordable food that can measurably reduce cognitive decline or delay its onset would represent an enormous public health win.

As study co-director Nancy Babio noted: “At a time when cases of cognitive decline and dementia are on the rise, our findings drive home the importance of improving diet quality, and in particular prioritising extra virgin olive oil over other refined versions as an effective, simple and accessible strategy for protecting brain health.”

What the Harvard Study Added

The PREDIMED-Plus findings fit neatly into a growing body of evidence.

The 2024 Harvard study, published in JAMA Network Open, tracked 92,383 American adults for 28 years and found that just over half a tablespoon of olive oil per day, roughly 7 grams, was enough to reduce the risk of dying from dementia by 28%.

That study spanned nearly three decades and controlled for a wide range of variables including genetics, lifestyle, and overall diet quality.

The association held regardless of whether participants otherwise followed a healthy diet.

The obvious limitation was that it did not distinguish between olive oil types.

The PREDIMED-Plus study steps into that gap.

Together, the two studies build a compelling picture: olive oil protects the brain, and extra virgin olive oil may do so more powerfully than its refined counterpart.

Quality Over Quantity: A Message Worth Repeating

Principal investigator Jordi Salas-Salvadó frames the findings in terms that are useful for everyday decisions.

“This research reinforces the idea that the quality of the fat we consume is as important as the quantity; extra virgin olive oil not only protects the heart, but can also help preserve the brain during ageing.”

That framing cuts against decades of dietary messaging that focused almost exclusively on the amount of fat consumed.

The Mediterranean diet, built around generous amounts of olive oil, was once viewed with suspicion in health circles because of its fat content.

Research since the 1990s has steadily overturned that view, and these latest findings reinforce the case that fat quality, especially the presence of bioactive compounds like polyphenols, is a more meaningful variable than fat quantity.

This is an important message for anyone navigating supermarket shelves or cooking choices.

Swapping refined olive oil, or worse, margarine and processed vegetable fats, for a high-quality extra virgin olive oil may be one of the most straightforward dietary moves available for long-term brain protection.

Practical Takeaways: What to Look For on the Label

Not all extra virgin olive oils are equal either.

The polyphenol content in extra virgin olive oil varies considerably depending on the olive variety, the region of production, the harvest timing, and the storage conditions.

Oils made from olives harvested early in the season, before full ripeness, tend to have higher polyphenol concentrations.

Cold-pressed and unfiltered varieties generally retain more bioactive compounds.

Darker bottles help protect the oil from light degradation.

Labels listing a specific harvest date and producer origin are good signs of quality.

In practical terms, look for extra virgin olive oil with a slightly bitter or peppery finish, which indicates the presence of oleocanthal and other polyphenols.

A completely mild or neutral-tasting olive oil, even if labelled “extra virgin,” may have lower polyphenol content.

Who Should Pay Attention

The PREDIMED-Plus study focused specifically on adults aged 55 to 75 who were overweight or obese and had metabolic syndrome.

That group is at elevated risk of both cardiovascular disease and cognitive decline, so the findings are particularly relevant for them.

But the underlying mechanisms, the effect of polyphenols on gut microbiota and the gut-brain axis, are not specific to this population.

Gut health and brain health are connected for everyone, and the dietary choices made in midlife are believed to shape cognitive trajectories in older age.

Medical News Today reported that this study adds meaningful evidence linking the type of olive oil consumed to the health of the gut-brain axis, a connection that researchers increasingly see as central to preventing cognitive decline.

Salas-Salvadó also noted that identifying a microbial pattern linked to the benefits of extra virgin olive oil “paves the way for new nutrition-based prevention strategies to preserve cognitive functions,” suggesting future interventions might become even more targeted.

A Simple Swap With Significant Potential

Cognitive decline is not inevitable, and the conversation around prevention is finally moving beyond medications and into the realm of everyday choices.

Diet sits at the centre of that conversation, and extra virgin olive oil is emerging as one of its most consistently supported players.

The evidence now connects it to heart health, metabolic health, gut microbial diversity, and cognitive function, across multiple large studies, multiple countries, and multiple biological mechanisms.

Replacing refined olive oil with extra virgin, or replacing margarine and processed fats with a high-quality bottle of cold-pressed extra virgin olive oil, is a change most people can make without disrupting how they cook or eat.

It costs a little more.

But the research increasingly suggests it may return something far more valuable.

If the gut really is the gateway to the brain, then what you pour into your pan each morning might be shaping how clearly you think decades from now.

That is worth thinking about, and perhaps worth sharing with someone you care about.