At a glance:
Research into high-polyphenol olive oil is producing some interesting findings, but it’s far from giving us all the answers. Some studies have found potential effects, while others have found little or no significant effect - and many of the findings still need to be confirmed through larger, better-controlled studies.
What’s new in olive oil polyphenol research?
Search for “olive oil polyphenols”, and you’ll find articles going back years. There are studies from more than a decade ago, articles circling the same findings, and plenty of claims that make it sound like we already know all there is to know about those fantastic compounds.
What’s easy to miss (unless you’re the kind of person who reads clinical trial registries for fun) is just how much new research has been published in the last two years.
Over the past two years, researchers have been asking new questions about what olive oil polyphenols could mean for cognition, blood sugar, gut health, and ageing. They’re also using newer methods to investigate effects that earlier research couldn’t explore in the same detail.
Some of the findings are giving researchers plenty to dig into, while others are still early and need more investigation. This article explores what the latest research is uncovering across these areas, as well as where the research is still in its early days.
The one claim that's actually authorised
Before we get into the research, we need to make an important distinction between what’s been established and what researchers are still investigating.
The only authorised UK and EU health claim for olive oil polyphenols says that they contribute to the protection of blood lipids from oxidative stress, when at least 5mg of hydroxytyrosol and its derivatives are consumed as part of 20g of olive oil a day. We’ve explained this claim and the research behind it in our does olive oil lower cholesterol? article if you want to explore the claim in more detail.
From here, we’re looking at the research rather than making health claims. We’ll be clear about what the studies have found and what they don’t prove.
Cognitive performance
Olive oil cognition research has become a growing area of study in recent years. It’s not an easy thing to study (changes in cognitive function can take years to develop), but early research has given scientists plenty to investigate further.
1. Tsolaki et al. (2020): MICOIL - Exploring olive oil polyphenols and cognitive function
The MICOIL study followed older adults who had already been diagnosed with amnestic mild cognitive impairment (a condition that affects memory) for 12 months. Participants were split into three groups: one consumed high-phenolic early-harvest olive oil daily, another consumed olive oil with a moderate phenolic content, and the third followed Mediterranean diet guidance only, with no specific olive oil provided.
Both olive oil groups performed better on several standard cognitive tests after 12 months than the group following dietary guidance alone. The high-phenolic group showed the most consistent improvements across the different tests.
What they found: Both olive oil groups performed better on several standard cognitive tests after 12 months than the group following dietary guidance alone. The high-phenolic group showed the most consistent improvements across the different tests.
Why it needs careful reading: This was a pilot study - an early look at the theory rather than a definitive answer. Everyone taking part already had mild cognitive impairment, which means the findings can’t tell us whether olive oil could help prevent cognitive decline in healthy people. Some of the individual results were only narrowly statistically significant, and the study had partial funding ties to an olive oil producer - which is another factor worth keeping in mind when looking at the findings. It’s useful human trial data, but researchers have said that larger, independently funded studies are needed to see whether the results hold up.
2. Simão et al. (2026): Exploring EVOO and cognitive function
What it looked at: Instead of looking at one trial, this recent review brought together the results of multiple randomised controlled trials. These trials investigated the effects of using high polyphenol extra virgin olive oil as a dietary intervention in older adults with mild cognitive impairment or dementia.
What they found: When researchers combined the results from the different trials, they found “a potential association between EVOO consumption and improvement in global cognitive function among older adults with MCI and dementia.” In other words, the results suggest a possible link, rather than proving that EVOO improves cognitive function.
How it compares with other research: MICOIL gave researchers one set of results, while this review brings findings from several trials together. That gives a broader view of the research so far and points in a similar direction. However, the studies included are still relatively recent and limited in number - so there’s more work to do before we can draw firm conclusions.
EVOO cognition research is still developing, and there’s plenty for researchers to keep exploring. But it hasn’t reached the point where olive oil polyphenols can be linked to an authorised health claim for memory or cognitive function. There’s also no authorised UK or EU health claim connecting olive oil polyphenols with memory, cognitive function or related conditions.
Blood sugar and metabolic health
When it comes to blood sugar and metabolic health, the research gets a little messier. Researchers are looking at several different effects, and the findings aren’t as straightforward as you might expect. So, what have they actually found?
3. Dehghani et al. (2021): Exploring EVOO and blood sugar control
A 2021 systematic review and meta-analysis published in Nutrition, Metabolism and Cardiovascular Diseases brought together 13 randomised controlled trials involving 633 people. The researchers wanted to see whether consuming extra virgin olive oil affected markers linked to blood sugar control - including fasting blood glucose, insulin and HOMA-IR (a measure commonly used to assess insulin resistance). They also looked at HbA1c, a longer-term measure of blood sugar.
What they found: When the results were combined, EVOO consumption was linked to small reductions in fasting blood glucose, insulin and HOMA-IR - but none of these changes were statistically significant. The researchers also looked at factors such as age, health status, the amount of olive oil consumed and how long people consumed it for, but none made a significant difference to the results.
How it compares with other research: Looking across 13 trials gives a much broader picture than any single study can. While the results didn’t show a clear effect on blood sugar markers, it helped set the stage for later studies looking at more specific groups of people.
4. Figueiredo-González et al. (2025): OILDIABET - Exploring high-polyphenol olive oil and blood sugar control
The 2025 OILDIABET trial took a more targeted approach, looking specifically at 116 adults with type 2 diabetes. Participants either consumed 30 mL of high-polyphenol EVOO each day for 24 weeks or were advised to minimise EVOO and use refined olive oil instead. Researchers measured fasting glucose, HbA1c, fasting insulin and HOMA-IR, among other markers.
What they found: The results weren’t quite as simple as “olive oil improved blood sugar”. Across the full group, the researchers found an improvement in HOMA-IR, but there was no significant difference in fasting glucose between the EVOO and control groups. Some of the more noticeable changes appeared in smaller subgroups. Participants with obesity had lower fasting glucose, estimated average glucose and HbA1c, while those who started with higher insulin resistance saw improvements in fasting insulin and HOMA-IR.
How it compares with other research: The OILDIABET trial doesn’t simply overturn the earlier review. In fact, both found that the overall results weren’t enough to show a clear effect across everyone taking part. What makes the newer study useful is that it starts to look more closely at who might respond differently. The changes seen among participants with obesity or higher insulin resistance raise the possibility that existing metabolic health could matter - although these findings need to be tested in more studies.
A quick word on the gut
Olive oil and the gut microbiome is another area researchers are starting to explore, with early studies looking at how polyphenols interact with gut bacteria and what that might mean for the body. The research is still fairly early, though, so it’s too soon to make broad claims about the benefits of high-polyphenol EVOO for gut health.
5. Martín-Peláez et al. (2016): Exploring olive oil polyphenols and the gut
The 2016 paper Influence of Phenol-Enriched Olive Oils on Human Intestinal Immune Function gives us an early look at how high-polyphenol olive oil might interact with the gut. Researchers followed 10 people who consumed oils with different levels of phenolic compounds over three-week periods, including one particularly high-polyphenol EVOO.
What they found: The high-polyphenol olive oil increased the proportion of bacteria coated with IgA, an antibody involved in the gut’s immune response. The researchers also saw changes in some other markers linked to intestinal immune function - although the results weren’t consistent across all the olive oil tested.
It’s a small, early study, so there’s still plenty to learn about how high-polyphenol olive oil interacts with the gut and what these findings might mean. We’ll be looking at this research in more detail in a dedicated gut-health piece soon.
What about heart health and inflammation?
If you want to dig deeper into the cardiovascular research, studies such as EUROLIVE have looked at how different levels of olive oil polyphenols affect blood lipids, alongside research into HDL function, LDL oxidation and blood vessel response. We’ve covered this in more detail in our olive oil polyphenols and cardiovascular health research article.
Inflammation and joint health are other areas researchers are investigating, including whether olive oil polyphenols may play a role. We’ve covered that research in more detail in our piece on olive oil and arthritis.
The bigger picture
So, where does all this leave us? There’s a lot more happening in olive oil polyphenol research than there was a few years ago, and it’s all looking at some very different questions.
The findings so far give researchers plenty to explore, but they also show why it’s important to look at the study behind each one and what it can actually tell us. Some studies are small, some findings need to be tested in larger groups, and some areas are still at an early stage.
We’ll keep following the research as new studies add to what we know about EVOO. In the meantime, if you’re interested in how that research translates to the bottle, explore our latest olive oil articles, or read our guide on how to buy olive oil - covering everything from harvest dates and freshness to lab-tested polyphenol levels.
Frequently Asked Questions
Does research support olive oil polyphenols for brain health?
Early human trials, including a 12-month randomised study in people with mild cognitive impairment, have found improvements in some cognitive assessments compared with a Mediterranean diet without a specified olive oil. This is still an area of active research, though, and there’s currently no authorised UK or EU health claim relating olive oil polyphenols to cognitive function.
Can olive oil polyphenols help with blood sugar control?
The research so far is mixed. Earlier studies found little overall change in blood sugar markers, while newer research has found some changes in people who already have insulin resistance or obesity. More studies are needed to see whether these findings hold up, and there’s currently no authorised health claim linking olive oil polyphenols with blood sugar control.
Is there research on olive oil and gut health?
Yes. Researchers have looked at how olive oil polyphenols interact with gut bacteria, microbial metabolites and the gut’s immune system, including in human studies. There are some interesting findings, but there’s still more to learn about what these changes actually mean for gut health.
What are the health benefits of hydroxytyrosol?
Hydroxytyrosol is one of the polyphenols naturally found in olive oil. Researchers have studied it in areas including oxidative stress, heart health and cognitive function. There’s more research in some areas than others, so it’s important to look at each finding in context rather than treating every result as a proven health benefit.
What are the benefits of oleocanthal?
Oleocanthal is another compound found naturally in extra virgin olive oil. Researchers are particularly interested in how it interacts with processes linked to inflammation. There are some interesting findings, but more research is needed to understand what they mean - for now, oleocanthal benefits are a subject of research rather than an authorised health claim.
What is the best olive oil for oleocanthal?
There isn’t one simple answer to this. The amount of oleocanthal in olive oil can vary depending on things such as the olive variety, when the olives were harvested and how the oil was made. If you’re looking for an oil with higher oleocanthal levels, check whether the producer provides information about what has actually been tested.
Why do you keep saying “research” instead of “benefits”?
Because a research finding isn’t the same as an established health benefit. A study can find a potential effect, but that doesn’t automatically mean we can say that olive oil has that benefit. This is particularly important when looking at phenolic olive oil benefits, because research into individual olive oil compounds is still developing. We use “research” where the evidence is still being investigated, so it’s clear what scientists have found and what they haven’t.
Scientific references
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Figueiredo-González M, et al. (2025). Exploring Galician phenolic-rich olive oil as a glycemic control strategy: the OILDIABET randomized trial. Food & Function.
Scientific and nutritional information disclaimer
The information on this website is provided for educational and informational purposes only and summarises published scientific research and general nutritional information relating to olive oil and olive polyphenols. It is not intended as medical, nutritional or dietary advice and should not be relied upon as a substitute for advice from your doctor, registered dietitian or other qualified healthcare professional.
Scientific studies reflect the findings of their respective authors and should not be interpreted as evidence that the same results will occur for every individual or from the consumption of any particular product.
Any health claims made in relation to our products are limited to those expressly authorised under applicable UK and EU nutrition and health claims legislation.
