Polyphenols in Olive Oil: What They Are and Why They Matter

Quick answer: Polyphenols in olive oil are natural compounds from the olive, mainly hydroxytyrosol, tyrosol, oleuropein derivatives and oleocanthal. They make fresh extra virgin olive oil taste bitter and peppery. Levels are given in mg/kg: above about 250 mg/kg is commonly called high polyphenol olive oil, and our published lab analyses show 512–810 mg/kg.

Polyphenols in olive oil are natural compounds the olive tree makes to defend its fruit. When olives are picked at the right moment and pressed gently and quickly, many of those compounds survive into the oil. They are a large part of what separates a fresh extra virgin olive oil from a tired, bland one, and they are the reason a good oil tastes green, bitter and peppery.

This guide explains what polyphenols are, what the EU allows to be said about them, why they fade, and how to read the number on a lab report. It is general information, not medical advice.

Key takeaways

• Polyphenols (also called phenolic compounds) in olive oil include hydroxytyrosol, oleuropein and oleocanthal. They give extra virgin olive oil its bitterness and its peppery finish.
• The EU authorises one health claim for olive oil polyphenols, with strict conditions: at least 5 mg of hydroxytyrosol and its derivatives per 20 g of oil.
• Polyphenols fall with age, heat, light and oxygen, so harvest date and storage matter as much as the number itself.
• A figure above roughly 250 mg/kg is usually called high polyphenol olive oil. Ask for the figure, the batch and the method used to measure it.

What are polyphenols in olive oil?

Olives contain a family of phenolic compounds. A handful of them do most of the work in the oil you pour:

• Hydroxytyrosol and tyrosol, together with their derivatives. These are the compounds named in the EU health claim below.
• Oleuropein, the main bitter compound in the olive fruit and leaf. As the olives are crushed and the oil ages, it breaks down into smaller compounds, hydroxytyrosol among them.
• Oleocanthal, the compound mainly responsible for the sting you feel at the back of the throat.

Greener, earlier-harvested olives generally carry more of them than fully ripe fruit. The variety matters too. Koroneiki, the small olive grown across Crete, tends to give oils that are naturally rich in polyphenols.

Why extra virgin olive oil tastes peppery and bitter

That peppery catch in the throat, and the clean bitterness across the tongue, are polyphenols announcing themselves. People new to high polyphenol oil sometimes mistake this for a fault, and a cough after a spoonful can come as a surprise. It is usually a sign of freshness. A completely soft, neutral oil often means the polyphenols are long gone.

Real faults taste different: musty, rancid, greasy or vinegary. If you want to learn the difference, our guide on how to spot a truly great extra virgin olive oil walks through it step by step.

One common mix-up is worth clearing up. Acidity and polyphenols are two separate measurements. Free acidity tells you about the condition of the fruit and how the oil was made, and it says nothing about the phenolic level. We explain it in acidity in olive oil: what it really means.

What the EU health claim says about olive oil polyphenols

In the EU, health claims for food are permitted only in the exact wording authorised by law. For olive oil there is one, in Commission Regulation (EU) No 432/2012: “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress.”

The claim may only be used for an oil that contains at least 5 mg of hydroxytyrosol and its derivatives (for example the oleuropein complex and tyrosol) per 20 g of olive oil, and the consumer must be told that the beneficial effect is obtained with a daily intake of 20 g of olive oil. In everyday terms, 20 g is about one and a half tablespoons.

It is a narrow, carefully worded claim. It does not say that olive oil treats or prevents any condition, and it is not personal advice. It is, though, the reason the number on a lab report is more useful than any adjective on a label. For the wider question of what olive oil does and does not do for your health, see is olive oil healthy.

Why polyphenols fade: freshness and storage

Phenolic content is highest at pressing and declines with time, heat, light and oxygen. Early harvest, pressing the olives immediately, cold extraction, nitrogen storage and light-proof packaging are not marketing steps. Each one is a way of losing fewer polyphenols between the tree and your kitchen. Our production standards show how we apply every step, from early harvest to light-proof filling.

You can do your part at home:

• Keep the oil in a cool, dark cupboard, away from the hob and from sunlight.
• Close the tin or bottle tightly after each use, because oxygen is the enemy.
• Buy a size you will finish within a few months of opening, and check the harvest date, not just the best-before date.

We publish the harvest date and the lab report for each batch, including the K232 and K270 values that show how oxidised an oil is. They are the other half of the picture, as we explain in our guide to choosing a great extra virgin.

What counts as high polyphenol olive oil?

There is no legal grade called “high polyphenol” olive oil. It is a description, and it only means something when a number sits behind it. The usual rule of thumb is 250 mg/kg, the level that matches the EU claim threshold of 5 mg per 20 g. Our published Memilon Crete analyses show 610 mg/kg, roughly 2.4 times that line.

How to read a polyphenol number in mg/kg

Polyphenols are reported in milligrams per kilogram of oil (mg/kg), which is the same as parts per million. A few things help you read the figure sensibly:

• The line. An oil is often described as high polyphenol above roughly 250 mg/kg. Notice that 5 mg per 20 g works out at 250 mg/kg, which is where that rule of thumb comes from.
• The method. A “total polyphenols” figure and the specific hydroxytyrosol-and-derivatives measurement behind the EU claim are not the same test, so the numbers are not directly interchangeable.
• The date. A result from pressing day describes the oil at its best. Ask which batch and harvest the figure belongs to.
• The source. If a producer cannot tell you the figure for the bottle in your hand, that itself is information. For our oils, you can look up the polyphenol figure for your batch by the LOT number on the tin or bottle.

A higher number also means a stronger taste. That is not better in every dish, which is why we make more than one oil.

How to use high polyphenol olive oil in the kitchen

Treat it as an ingredient with a voice. Used raw, it keeps the most flavour and the most polyphenols.

• Finish dishes with it. A generous drizzle over grilled vegetables, bean soup, fish or a soft-boiled egg lifts them. Bitterness loves salt, acid and bread.
• Dress salads and dip bread. It is the heart of a proper Greek salad and of Cretan dakos, where tomato and salty cheese soften the pepper.
• Cook with it. Good extra virgin olive oil copes with everyday cooking better than most people expect, as our guide to cooking with extra virgin olive oil explains. Some polyphenols are lost to heat, but the flavour carries through in dishes like Greek lemon potatoes, and it makes a moist, fragrant lemon olive oil cake.

From our range

• Memilon BIO Crete is certified organic early-harvest Koroneiki, high in polyphenols (810 mg/kg in its lab analysis) and grown without pesticides. It is picked earliest, which is why its phenolic content runs highest in our range. It is a finishing oil, first.
• Memilon Crete is 100% Koroneiki from Phaistos in the Messara plain, with 0.29–0.31% acidity and 610 mg/kg polyphenols in our lab analyses. It is cold extracted below 27°C (80°F).
• Memilon Lesvos is the gentle one. Made from the rare Kolovi variety in Plomari, it sits lower in polyphenols (512 mg/kg) and is elegant, balanced and delicately fragrant. Choose it if you prefer a softer taste.

You can see all three, with free shipping on every order, in our Greek olive oil collection.

Polyphenols in olive oil: frequently asked questions

What are polyphenols in olive oil?

They are natural phenolic compounds from the olive, such as hydroxytyrosol, oleuropein and oleocanthal. They are responsible for much of the bitterness and pepperiness of fresh extra virgin olive oil.

What is hydroxytyrosol?

Hydroxytyrosol is one of the main polyphenols in olive oil. Part of it forms from the breakdown of oleuropein as the olives are crushed and the oil ages. Together with its derivatives, it is the compound group named in the only EU-authorised health claim for olive oil polyphenols, which applies from 5 mg per 20 g of oil.

What is oleocanthal?

Oleocanthal is the olive oil polyphenol behind the peppery sting at the back of the throat. It was identified and named in 2005 by researchers who traced that throat sting to this compound. Fresh, early-harvest oils usually carry more of it than mild oils from ripe fruit.

Why does olive oil make me cough?

Oleocanthal triggers a peppery sting at the back of the throat. A cough or tickle from a fresh, green oil is normal and usually a sign of high polyphenols, not of a fault.

How much olive oil does the EU health claim refer to?

The authorised wording refers to a daily intake of 20 g of an olive oil containing at least 5 mg of hydroxytyrosol and its derivatives per 20 g. It describes the basis of the claim and is not a personal recommendation.

Does cooking destroy the polyphenols?

Some are lost with heat and time, so using the oil raw keeps the most. Cooking with a good extra virgin olive oil is still a fine choice for flavour.

Is a higher mg/kg figure always better?

Not always. A higher figure means a stronger, more bitter and peppery oil, which suits some dishes more than others. Freshness, a published lab report and honest storage matter as much as the number.

How can I tell if an oil is high in polyphenols?

Taste it fresh: green, bitter and a peppery catch in the throat are good signs. The reliable answer is a batch lab report showing the mg/kg figure and the method.

The short version: buy fresh, buy tested, and let the pepper at the back of your throat tell you the rest.

Sources

• Commission Regulation (EU) No 432/2012: list of permitted health claims, including the olive oil polyphenol claim and its conditions of use.
• Our own batch analyses: look up the polyphenol figure of your bottle by its LOT number.

This article is general information about olive oil and does not replace advice from a doctor or dietitian.