Polyphenols and oxidative stress

What is oxidative stress?

Oxidative stress occurs when the body produces free radicals faster than it can neutralise them. Free radicals are reactive molecules formed naturally during metabolism but which, in excess, can damage cells, proteins and lipids. Among the lipids susceptible to oxidation are the fats circulating in the blood — blood lipids.

The body has its own defences against oxidation, and diet can contribute to supporting them. This is the context in which the relationship between olive oil polyphenols and the protection of blood lipids from oxidative stress has been studied.

The authorised EFSA claim

The European Food Safety Authority (EFSA), acting under EU Regulation 432/2012, has authorised the following health claim for olive oil:

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

This is an Article 13.1 claim — based on a systematic review of published research. It is one of very few authorised health claims for olive oil, and it is worded with precision. It addresses specifically the role of polyphenols in relation to the oxidation of blood lipids — not a broader effect on health or disease in general.

Conditions of use

The EFSA authorisation is conditional. For an olive oil to carry the claim, it must provide at least 5 mg of hydroxytyrosol and its derivatives — for example oleuropein complex and tyrosol — per 20 g of oil consumed daily. Not all olive oils qualify; the polyphenol content must be high enough.

EFSA also requires that consumer information state that "the beneficial effect is obtained with a daily intake of 20 g of olive oil." This is an information requirement attached to the authorisation — not a recommendation from Vala Selection.

What 1004 mg/kg means in relation to the threshold

Vala Selection's current reference batch — 2025-VL-MIR-001 — has a measured polyphenol content of 1004 mg/kg, analysed by HPLC at the University of Split. The comparable threshold under EFSA Regulation 432/2012 translates to approximately 250 mg/kg in total polyphenols. This batch exceeds that threshold by a wide margin.

It is important to keep the figures in perspective: 1004 mg/kg is a measured value for this specific batch, not a guarantee for future batches. Polyphenol content varies with harvest year, weather conditions and harvest timing. Each batch is analysed separately and documented with a unique batch ID in the format YYYY-VL-CCC-NNN. Our guaranteed minimum per harvest is 700+ mg/kg.

The polyphenol ladder — what the numbers mean in category context

Polyphenol content varies considerably across olive oils on the market:

100–250 mg/kg     ordinary olive oil
250–350 mg/kg     premium olive oil
700+ mg/kg        Vala Selection Core (guaranteed minimum)
1000+ mg/kg       Vala Selection Pre-harvest (target value)

Source for category ranges: IOC Trade Standard (COI/T.15/NC No 3/Rev. 16). Vala Selection's own figures: HPLC analysis, University of Split.

The difference is not gradual — it is a category shift. An oil at 700+ mg/kg operates in a different functional register than one at 100 mg/kg.

How HPLC analysis works

The polyphenol content of Vala Selection's oil is measured by high-performance liquid chromatography — HPLC. The method separates the individual polyphenol compounds in an oil sample and quantifies each one with high precision. It is not an estimate or an index; each compound is measured and summed to a total.

Analysis is carried out at the University of Split, one of the leading institutions for food chemistry and olive oil research in the region. The result is expressed in milligrams of polyphenols per kilogram of oil (mg/kg) — the same unit used in the EFSA regulation — and is the value quoted on the product and in product documentation.

What the claim does not mean

A polyphenol content above the EFSA threshold is a necessary condition for the authorised claim to apply — but not a sufficient one in itself. The oil must also meet the requirements for extra virgin classification, maintain adequate quality, and be consumed in the quantity EFSA specifies.

The claim says nothing about olive oil as an isolated therapeutic substance or about a specific medical outcome for a named condition. No food product — including olive oil — may be marketed as a treatment, cure or preventive measure for a specific diagnosis. Olive oil's place is in a well-balanced diet.

The connection to handling and storage

There is a direct relationship between high polyphenol content and how olive oil is handled from harvest to bottling. Polyphenols begin to degrade as soon as olives are harvested, and the process accelerates if pressing is delayed. Keeping the time from harvest to mill as short as possible — in Vala Selection's case within 24 hours — is one of the most important factors in preserving polyphenol content in the final product.

The same applies to storage after bottling: light, heat and contact with air accelerate breakdown. Dark glass and storage at room temperature away from direct light are not merely aesthetic choices — they are functional requirements for keeping polyphenol content stable through to consumption.