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Polyphenols

Everyone is talking about polyphenols. Here is what the lab and the law actually say.

Polyphenols are the olive’s own chemistry. They make fresh oil bitter and peppery, they fade with time, and they can be measured. So we measure them, batch by batch, and publish the sheet. This page is what we know, what we measured, and where we stop.

548.9mg/kg · EVOO
643.7mg/kg · EVOO Centenarian
10.6mg per 20 g · EU line is 5

Total polyphenols, measured by Chem Solutions, Athens, January 2026. Hydroxytyrosol line: EVOO Centenarian.

What they are

The olive makes them to protect itself.

An olive hangs on the tree for months, in sun, wind and heat. Polyphenols are part of how it defends itself. When the fruit is crushed, some of them pass into the oil. Most of the ones that make it into the bottle are bitter or pungent. That is how you taste them.

Chemically, a phenol is a benzene ring carrying at least one hydroxyl group. Polyphenols are the family of them. Our lab report lists more than fifteen. Three are worth knowing by name:

  1. A
    Hydroxytyrosol and tyrosol

    The compounds behind the EU health claim, measured together with their derivatives. 10.6 mg per 20 g in our EVOO Centenarian.

  2. B
    Oleocanthal

    The catch at the back of your throat. On the lab report it hides under its chemical name, DDLA: 87.2 mg/kg.

  3. C
    Oleacein

    Oleocanthal’s sister compound. Listed as DDOA: 53.0 mg/kg.

And the rest

Polyphenols are not the only thing in the bottle worth having.

About 99% of olive oil is fat, most of it oleic acid: the monounsaturated fat the FDA claim is about. The last 1% or so is where the rest of the character lives (Jiménez-Sánchez et al., 2022):

  • Vitamin E, mostly alpha-tocopherol: 150 to 250 mg/kg in extra virgin oil.
  • Plant sterols, three quarters or more of them beta-sitosterol.
  • Carotenoids such as beta-carotene, and chlorophyll. Together they give the oil its color.
  • And the phenols on this page.

The claim

The EU allows olive oil exactly one health claim.

“Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress.”

That is the wording, word for word, from Regulation (EU) No 432/2012. It is only allowed for oil with at least 5 mg of hydroxytyrosol and its derivatives per 20 g, and the benefit comes with a daily intake of 20 g, about 1½ tablespoons.

Our EVOO Centenarian measures 10.6 mg. More than twice the line. Not on a promise. On the lab sheet.

In the U.S. there is no polyphenol claim at all. The FDA allows a qualified claim about the fat in olive oil instead.

The FDA’s qualified claim, word for word“Limited and not conclusive scientific evidence suggests that eating about 2 tablespoons (23 grams) of olive oil daily may reduce the risk of coronary heart disease due to the monounsaturated fat in olive oil. To achieve this possible benefit, olive oil is to replace a similar amount of saturated fat and not increase the total number of calories you eat in a day. One serving of this product contains 14 grams of olive oil.” See the nutrition facts for fat content.

Why they fade

Polyphenols don’t last forever. That is the point of a harvest date.

Polyphenols don’t only protect the olive. In the bottle, they protect the oil itself: they slow the oxidation that turns oil rancid. Together with the high share of oleic acid, they are why good olive oil keeps.

They are highest in oil from greener fruit. As olives ripen on the tree, the count goes down, and the oil becomes less stable with it (Ayton et al., 2007).

After pressing, the clock keeps running. Light, heat and air break them down. Dark, cool storage and less air in the bottle slow it (Monasterio et al., 2023). Over years the loss is real: one oil kept at room temperature lost about a quarter of its polyphenols in four years, and about two thirds in eight (Baiano et al., 2014).

That is why our label carries the harvest month, not just a best-before. And why the polyphenol number lives in the lab analysis, with its test date, instead of on the bottle.

  • Keep it in the dark glass it came in.
  • Away from the stove and the window.
  • Cap on after every pour.
  • Use it. Olive oil is not wine; it does not get better with age.

Taste them

Your tongue is a decent lab.

Bitterness on the tongue and a peppery catch in the throat are the polyphenols at work. The catch is oleocanthal. Oil that tastes flat, buttery or of nothing has few left, whatever the label says.

  1. Pour a spoonful. Warm it in your hand for a minute.
  2. Smell it first: green almond, cut grass, artichoke.
  3. Sip, pull in a little air, and swallow.
  4. Wait for the catch in your throat.

What the research says

Promising. Not magic.

Oleocanthal and ibuprofen. In 2005, researchers reported in Nature that oleocanthal acts on the same enzymes as ibuprofen, in the lab (Beauchamp et al., 2005). That is a finding about a molecule in a test tube. It does not mean a spoon of oil works like a pill, and we will never tell you it does.

PREDIMED. The best-known diet trial on olive oil followed 7,447 adults in Spain at high cardiovascular risk for almost five years. The group on a Mediterranean diet with extra virgin olive oil had about 30% fewer major cardiovascular events than the group on a reduced-fat control diet (Estruch et al., 2018). It tested a whole way of eating, not polyphenols alone.

What we won’t say. You will read online that olive oil cures half the diseases on earth. Some of that research is promising. None of it lets a bottle make that promise. So ours doesn’t.

Where that leaves us. Real extra virgin olive oil, used every day in place of other fats, belongs in a good diet. Food, not medicine. A spoon a day is a habit, not a treatment.

Reading the numbers

Not every polyphenol number is the same number.

There is no official definition of “high phenolic”. Some researchers draw the line at 500 mg/kg (Jiménez-Sánchez et al., 2022). Both of ours clear it: 548.9 and 643.7.

Two labs can test the same oil and print different figures. Ours uses HPLC, the International Olive Council’s method (COI/T.20/Doc. No 29). Many brands that sell on very high counts use NMR, a different method, and the two sets of numbers can’t be set side by side. Compare like with like, or don’t compare.

Before you trust any number, ours included, ask three questions: which lab, which method, which date. If a producer can’t answer, the number is decoration.

Read our lab analysisShop EVOO Centenarian

Sources

Read it yourself.

Last reviewed October 2026.

The harvest letter

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