Polyphenols in olive oil

This page explains what polyphenols are, why they are found in olive oil, and what the content says about an oil's composition. If you arrived here from a post on a specific topic β€” welcome. No prior knowledge is required.

What are polyphenols?

Polyphenols are a large group of organic compounds that occur naturally in plants. They act as the plant's own defense against sun, pests, and oxidation β€” a chemical defense system located in leaves, bark, seeds, and fruits.

In the olive tree, polyphenols are found mainly in the leaves and the olive fruit. When the olive is pressed into oil, some of the polyphenols dissolve in the fat and end up in the final product. Which ones and how many depend on the olive variety, ripeness, and how the pressing is handled.

Which polyphenols are found in olive oil?

Olive oil contains several subgroups of polyphenols. The most notable belong to the group of secoiridoids β€” a type of compound specific to the olive family (Oleaceae):

  • Oleocanthal β€” gives the characteristic peppery sensation in the throat and is the compound most studied for its chemical similarity to ibuprofen. Read more about oleocanthal in olive oil.
  • Oleuropein and its derivatives β€” the predominant polyphenol compound in the olive fruit itself and the primary source of bitterness in oil. Read more about oleuropein in olive oil.
  • Hydroxytyrosol and tyrosol β€” simpler polyphenol compounds formed when oleuropein breaks down during pressing and storage. It is these, along with the oleuropein complex, that the EU-approved EFSA claim regarding blood lipids and oxidative stress specifically applies to. Read more about polyphenols and oxidative stress.

Why does the content vary so much?

The polyphenol content in olive oil can vary tenfold between a cheap supermarket variety and a carefully managed oil from an early harvest. This is due to an interplay of factors:

Olive variety. Different olive varieties (cultivars) produce polyphenols in varying amounts. Lastovka, the olive variety grown in Vela Luka on Korčula, is among the varieties that consistently yield high polyphenol values.

Harvest time. The content is highest in unripe, green olives early in the season. The more the olive ripens, the lower the content β€” in parallel with an increase in yield. Early harvests result in lower volume but more polyphenol-rich oil.

Time from harvest to pressing. Polyphenols begin to break down immediately after harvest. Every hour of waiting is an hour of degradation. Vala Selection's olives are pressed within 24 hours of harvest β€” this is not a marketing argument but a production decision that directly affects the final value.

Storage. Light, heat, and contact with air continue to break down polyphenols even in the finished oil. Dark glass and storage away from light slow down the process.

What the numbers mean in category context

Polyphenol content is measured in milligrams per kilogram of oil (mg/kg) using the HPLC method. Observed ranges in the market:

100–250 mg/kg    regular olive oil in grocery stores
250–350 mg/kg    premium olive oil
700+ mg/kg       Vala Selection CORE (guaranteed minimum per harvest)
1000+ mg/kg      Vala Selection Pre-harvest (target value)

Vala Selection's reference batch 2025-VL-MIR-001 measured 1,004 mg/kg in HPLC analysis at the University of Split. This is a measured value for a specific batch, not an average and not a guarantee for every future harvest. Polyphenol content varies with harvest year and weather; each batch is analyzed separately.

What this does not imply

High polyphenol content is a compositional measure β€” it describes what is in the oil, not how the body reacts to it. Polyphenols in olive oil are food components, not medicines or dietary supplements.

The only EFSA-approved health claim for olive oil polyphenols concerns the protection of blood lipids from oxidative stress, and it is strictly conditional. Read the full review on the page about polyphenols and oxidative stress.

No food product β€” including olive oil with high polyphenol content β€” may be marketed as a treatment for a disease.

How is polyphenol content measured?

The method is called HPLC β€” high-performance liquid chromatography. A complete overview of how the analysis works and what a value in mg/kg actually represents can be found on the page about HPLC analysis of olive oil.

More information

Current values, batch information, and references can be found on the product page.

Sources: Observed market ranges; category definitions according to IOC Trade Standard COI/T.15/NC No 3/Rev. 16. EU Regulation 432/2012 on authorized health claims. HPLC analysis performed at the University of Split. Batch 2025-VL-MIR-001.

Back to blog