What are polyphenols and why do they make olive oil healthy?

What are polyphenols and why do they make olive oil healthy?

Reading time: approx. 5 minutes  |  Category: Olive oil knowledge  |  Uliveto di Mede

You have probably come across the word on an olive oil bottle or in an article about nutrition: polyphenols. But what exactly are they, why are they so important, and — perhaps most practically — how do you know whether your olive oil contains enough of them?

In this article we explain it clearly. No complicated jargon, just concrete information to help you make a better choice on the shelf or online.

Polyphenols are natural bioactive compounds found in plants. They act as a kind of defence mechanism for the plant: they protect the olive tree against UV radiation, drought, fungi and insects.

For us, they are interesting for another reason: in the body, polyphenols work as powerful antioxidants. They neutralise free radicals — unstable molecules that damage cells and contribute to ageing and inflammation.

More than 25 different polyphenols have been identified in extra virgin olive oil. The best known are:

•      Oleocanthal — the compound responsible for the tingling sensation in your throat

•      Oleuropein — a powerful antioxidant, responsible for the bitter taste

•      Hydroxytyrosol — one of the strongest plant antioxidants known

•      Tyrosol — supports cardiovascular health

Do you know that slightly burning sensation at the back of your throat when you taste olive oil neat? That is oleocanthal at work — and it is one of the best quality signals there is.

Oleocanthal has anti-inflammatory properties comparable to ibuprofen, but in an entirely natural way. Researchers at the Monell Chemical Senses Center in Philadelphia discovered this in 2005 and published their findings in the journal Nature.

The more you cough after tasting, the more oleocanthal the olive oil contains. No tingle? Then the oil probably contains few or no polyphenols any more — a sign of refining or an old product.

Polyphenol content is measured in mg/kg (milligrams per kilogram of oil). Here is a practical reference table:

Polyphenol content — frame of reference:

> 400 mg/kg  →  Exceptionally high — premium artisanal olive oil

250–400 mg/kg  →  High — good artisanal product

100–250 mg/kg  →  Average — acceptable quality

< 100 mg/kg  →  Low — refined or old product

Industrial supermarket own-brand olive oil usually contains less than 80 mg/kg. That is less than a fifth of what a quality artisanal product achieves. The difference in health effect is therefore significant.

Polyphenols are fragile. They break down because of four factors:

•      Heat — refining at high temperatures destroys virtually all polyphenols

•      Light — UV radiation breaks down the compounds (the reason for dark bottles or tins)

•      Oxygen — oxidation after opening speeds up the loss

•      Time — even good olive oil loses polyphenols over the months

That is why cold pressing within a few hours of the harvest is so crucial. The longer the time between harvesting and pressing, the more polyphenols are lost through oxidation in the olive itself. At Uliveto di Mede, the olives are pressed the very same day at the local mill in Sicarico.

You do not need a lab to make an estimate. Look out for these signs:

1. Taste the olive oil neat

Take a small teaspoon and taste it without bread. A good olive oil is slightly bitter and peppery, and gives a tingling sensation at the back of the throat. Coughing is a good sign — it means oleocanthal.

2. Check the label

Does it say "cold-pressed" and give a harvest date? Producers who know what they are selling are transparent about when the olives were harvested. A "best before" date alone is not enough.

3. Look at the packaging

Dark glass bottle or tin? Good. Clear plastic bottle in full light? A warning sign. Light is the enemy of polyphenols.

4. Price as an indicator

Real artisanal extra virgin olive oil with a high polyphenol content costs at least €10–15 per litre. Olive oil that is cheaper is almost always refined, blended or of a different quality grade.

The scientific literature on polyphenols in olive oil is extensive. Some well-supported findings:

•      Regular consumption of polyphenol-rich EVOO is associated with a lower risk of cardiovascular disease, partly by reducing LDL oxidation (the "bad" cholesterol).

•      Oleocanthal inhibits the enzymes COX-1 and COX-2 — the same mechanism as ibuprofen. With a daily intake of 50 ml of olive oil, this effect is measurable.

•      Hydroxytyrosol and oleuropein have been shown in several studies to inhibit the growth of certain cancer cells — although this research is still very much ongoing.

•      A Spanish study (the PREDIMED trial, 2013) showed that participants who consumed extra virgin olive oil had 30% fewer cardiovascular events than the control group.

Important: olive oil is not a medicine. The health benefits are the result of daily, consistent use as part of a balanced Mediterranean diet.

Polyphenols are not just a marketing term. They are the reason why high-quality extra virgin olive oil is fundamentally different from the cheap supermarket kind — in flavour, in health effect and in production method.

Next time you buy a bottle of olive oil: look for the harvest date, taste the oil neat and pay attention to the tingle. That tingle is not a defect — it is proof that you have something real.