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Polyphenols are natural plant compounds found in foods such as olive oil, tea, berries and dark chocolate. Olive oil contains its own distinct polyphenols, and research suggests they may have health effects, although the wider health benefits of polyphenols are still being studied.
So, what exactly are polyphenols?
Walk into almost any health food shop and you'll see the word polyphenols attached to all sorts of products. Green tea, dark chocolate, red wine, olive oil - after seeing it enough times, it’s easy to lump them all in together. If they’re all being talked about in the same breath, they must be offering much the same thing… right?
Not quite. The polyphenols found in olive oil are very different from those found in all those other delicious foods and drinks. So, before we get into what the research says, it’s worth looking at what polyphenols actually are, where they come from and how the different types found in our food compare.
That’s what we’ll look at today.
What are polyphenols?
Polyphenols are a large family of natural compounds found in plants. There are thousands of different types, and plants make them for a few different reasons, including protecting themselves from UV light, pests and oxidative stress.
We come across these compounds all the time without noticing them. They’re in the foods and drinks we eat, and once they’re in the body, some polyphenols can act as antioxidants - helping to neutralise unstable molecules called free radicals before they can cause damage to cells.
If you’ve read any of our other articles, you’ll have heard the term mentioned here and there. Polyphenols are a big part of what we talk about at MasWorth, and for good reason. But olive oil certainly doesn’t have a monopoly on polyphenols; they’re found in everything from tea and coffee to berries, dark chocolate and red wine.
One of the things we find most interesting about polyphenols is that they’re all different. Different plants produce different compounds, which is why we need to look more closely at the particular compounds found in olive oil rather than lumping them all together.
Olive oil's polyphenols are a different chemical family
Many of the better-known polyphenols in foods such as green tea, berries and red wine belong to a group called flavonoids. Olive oil’s main polyphenols come from a different class altogether: secoiridoids. These compounds are closely associated with the olive tree and a few other members of the Oleaceae plant family, which includes olive trees, ash trees, jasmine and lilac.
That's part of why the research into the health benefits of olive oil polyphenols reads differently to, say, green tea's - it's a genuinely unique set of compounds, not simply more of the same antioxidants.
The four polyphenols that matter most in extra virgin olive oil:
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Oleuropein - found in particularly high amounts in unripe olives, where it contributes to their natural bitterness. As olives ripen and are processed into oil, oleuropein is broken down into smaller compounds, including some of the ones below.
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Hydroxytyrosol - one of the compounds formed as oleuropein breaks down. It’s also the compound behind the EU-authorised health claim for olive oil polyphenols, which we’ll come back to later.
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Oleocanthal - responsible for that familiar peppery, throat-catching sensation you can get from fresh extra virgin olive oil. We’ve gone into this one in much more detail in our separate article on oleocanthal.
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Oleacein - another compound formed from oleuropein as olives mature and are processed. It’s often studied alongside oleocanthal and has attracted interest for its antioxidant and anti-inflammatory properties, although there’s less research specifically on oleacein.
Why polyphenol content varies so much between oils
So, if olive oil can contain such different polyphenols, does every bottle contain roughly the same amount? Not quite.
Polyphenol content can vary hugely from one extra virgin olive oil to another. It can range from under 100 mg/kg to well over 1000 mg/kg - and there isn’t one simple reason for that difference.
A few things can influence how many polyphenols make it into the finished oil:
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Harvest timing - olives picked while they’re still green tend to have higher polyphenol levels than olives left to fully ripen.
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Olive variety - different olive varieties naturally produce different amounts and types of polyphenols.
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Milling and processing - how quickly and carefully the olives are processed can affect how much of their original polyphenol content ends up in the oil.
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Freshness and storage - polyphenol levels decline steadily after pressing, faster with heat and light exposure
That’s why seeing extra virgin on the label doesn’t necessarily tell you much about an oil’s polyphenol content. Two bottles can both be extra virgin and still contain wildly different amounts, with some oils containing ten times as many polyphenols as others.
The one claim that's actually authorised
There’s no shortage of claims about olive oil polyphenols online, so it’s worth taking a moment to separate what we know from what’s still being researched.
There’s currently one authorised health claim for olive oil polyphenols in UK and EU regulations: olive oil polyphenols contribute to the protection of blood lipids from oxidative stress.
There’s a catch, though. The oil needs to contain at least 5mg of hydroxytyrosol and its derivatives per 20g of olive oil, and you need to consume around 20g a day (roughly a tablespoon and a half) to meet the conditions of the claim.
That doesn’t mean the wider health benefits of polyphenols aren’t worth looking at. Researchers have explored their potential role in areas including heart, brain, joint and gut health, but this research hasn’t reached the point where those effects can be presented as authorised health claims.
We’ve covered that research in more detail in our research pieces, as well as how to check the polyphenol content of an olive oil when you’re choosing one.
Where this leaves you
Hopefully, that’s cleared up some of the confusion around polyphenols. There’s a fair bit to get your head around, but the basic picture is actually fairly simple.
There’s certainly a lot to be interested in when it comes to the benefits of polyphenol compounds in olive oil, but you don’t need to stretch the evidence to make a good case for them.
We know polyphenols have antioxidant properties, and research is continuing to explore what else these compounds might be doing in the body, but the amount of polyphenols in an oil can vary hugely, too.
If you’re looking for a high polyphenol olive oil and want to know exactly what you’re getting, we lab-test our own oils rather than asking you to take our word for it.
Our MasWorth Family Groves comes in at 965 mg/kg of polyphenols, while November Polyphenols contains more than 1200 mg/kg. Both are certified by the World Olive Centre for Health in Athens, and both are dated so you know when they were tested.
We think it’s much easier to know what you’re getting when the numbers are there in black and white - which is why we publish ours.
What are the health benefits of polyphenols? FAQs
Are polyphenols the same as antioxidants?
Not quite - polyphenols are one large category of plant compounds, many of which happen to act as antioxidants. Not every antioxidant is a polyphenol (vitamin C and E aren't), and not every polyphenol's main effect is antioxidant activity.
Which olive oil has the most polyphenols?
It depends entirely on harvest timing and freshness rather than brand or region alone. Early-harvest oils, properly lab-tested and dated, are the most reliable way to know. November Polyphenols is certified at 1200+ mg/kg by the World Olive Centre for Health in Athens, against 965 mg/kg for Family Groves.
Does cooking destroy olive oil's polyphenols?
Heat gradually degrades them, which is why high-polyphenol oils are generally best used raw or as a finishing oil rather than for high-heat cooking.
Is "high polyphenol" a regulated term?
No - unlike the specific EFSA claim above, "high polyphenol" itself isn't a legally defined labelling term in the UK or EU, so it's worth checking for an actual mg/kg figure rather than taking the phrase at face value.
Scientific & Nutritional Information
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.
