Hydroxytyrosol and Olive Polyphenols: An Overview

Hydroxytyrosol is one of the best-known polyphenols from the olive and from olive oil. It belongs to the secondary plant compounds and is found in particularly high concentration in extra virgin olive oil as well as in olives and olive leaves. For olive oil polyphenols there is an authorised health claim in the EU, which is tied to certain conditions. What hydroxytyrosol exactly is, where it occurs and what the authorised claim says, this overview puts into perspective.

What is hydroxytyrosol?

Hydroxytyrosol is a naturally occurring polyphenol from the group of phenolic alcohols. It forms, among other things, during the breakdown of oleuropein, the characteristic bitter compound of the olive. Chemically it belongs to the simple phenols and is significantly co-responsible for the typical, slightly bitter and pungent taste of high-quality olive oil.

Polyphenols are a large family of plant compounds that occur in many types of fruit, vegetables and plants. In the olive, hydroxytyrosol, tyrosol, oleuropein and oleocanthal together form a characteristic profile. These substances are one reason why extra virgin olive oil is regarded as a special product of the Mediterranean diet.

The term polyphenols stands for a very heterogeneous group. Common to all is a certain chemical basic structure with several phenolic groups. In plants, these compounds fulfil, among other things, a protective function against environmental influences. For humans they are interesting above all as a natural component of a plant-focused diet. Hydroxytyrosol takes a prominent position among the olive polyphenols, because it is expressly named in EU legislation and serves as a reference value for an authorised claim.

The authorised EU claim for olive oil polyphenols

For polyphenols from olive oil there is an authorised health claim in the EU: olive oil polyphenols contribute to the protection of blood lipids from oxidative stress. This claim may, however, only be used under one clear condition: it applies to olive oil that contains at least 5 mg of hydroxytyrosol and its derivatives (such as oleuropein complex and tyrosol) per 20 g of olive oil.

The positive effect is achieved, according to the claim, with a daily intake of 20 g of this olive oil. Important is the exact wording: it is about the protection of blood lipids from oxidative stress, not about general statements on the heart, circulation or other complaints. This claim is tied to the consumption of correspondingly polyphenol-rich olive oil.

This comparatively precise wording is typical of the European system of authorised claims. Before a health claim may be used, it is scientifically assessed and provided with clear conditions, for example a minimum amount of the efficacy-determining substance and a daily consumption amount. For consumers this means: a claim on a package is not arbitrary, but tied to verifiable criteria. If these details are missing or the effect is described more generally than the authorised wording allows, scepticism is appropriate.

Occurrence: where hydroxytyrosol is found

The most important everyday source of hydroxytyrosol and related polyphenols is high-quality extra virgin olive oil. The polyphenol content, however, fluctuates strongly, depending on olive variety, degree of ripeness, production and storage. Freshly pressed, single-variety oils with an intense, slightly bitter taste tend to contain more of these compounds.

Freshness also plays a role: polyphenols break down over time, which is why an oil loses content over the months after the harvest. A current harvest year and prompt use after opening are therefore advantageous. Anyone who wants to keep the content as high as possible tends to buy smaller bottles that are used up quickly, and stores them protected from light. The often scratchy-perceived, slightly pungent impression in the throat when tasting a good oil is, by the way, a sensory indication of a higher polyphenol proportion and no sign of inferior quality.

Whole olives and olive leaves also contain hydroxytyrosol and oleuropein. As a food supplement, hydroxytyrosol is additionally offered in capsules or as a component of olive extracts. Whether a preparation is sensible depends on the individual diet; anyone who regularly uses high-quality olive oil already takes in olive polyphenols through their food.

It should be borne in mind that refined olive oils lose a large part of their polyphenols in the course of processing. That is why the category is decisive: only extra virgin olive oil, which is obtained mechanically without strong heating and without chemical treatment, retains its full polyphenol profile. A cheap, taste-neutral oil accordingly supplies fewer of these compounds than an intensely tasting, freshly pressed oil. Anyone who specifically pays attention to olive polyphenols should therefore look less at individual preparations than at the quality of the daily used oil.

Intake and everyday use

For hydroxytyrosol as an isolated food supplement substance there is no officially set recommended daily amount. Anyone who uses a preparation should follow the manufacturer's consumption recommendation. The authorised EU claim refers expressly to olive oil with the stated minimum content and the daily amount of 20 g, which corresponds to about two tablespoons.

In everyday life, polyphenol-rich olive oil can be used in many ways: over salads, vegetables, with bread or as a finish to dishes. Since heat and light can break down polyphenols, use as a cold-added oil and a dark, cool storage is sensible in order to retain the content as much as possible.

What you can pay attention to when buying

With olive oil, the category extra virgin olive oil, a harvest date, a dark bottle and an intense taste are good indicators of a polyphenol-rich product. Some manufacturers state the polyphenol content, which makes comparisons easier. A slightly bitter, throat-scratching impression often points to a higher polyphenol proportion.

With food supplements containing hydroxytyrosol, it is worth looking at the stated amount, the standardisation and an ingredient list that is as short as possible. Make sure that advertising statements do not go beyond the permissible scope. Reputable providers stick to the authorised claims and refrain from healing promises. A preparation that advertises with vague but grandiose formulations is more of a warning signal than a quality feature. Conversely, a factual presentation tied to the claim speaks for a responsible handling of the topic.

Safety and classification

Through the normal diet with olive oil, the intake of olive polyphenols is considered unproblematic for healthy adults. With concentrated food supplements, the recommended amount should not be exceeded. Pregnant women, breastfeeding women, people with illnesses and persons who take medication best consult a doctor before taking preparations, since interactions cannot always be ruled out.

Overall, hydroxytyrosol and the other olive polyphenols are a well-researched, characteristic component of the Mediterranean diet. The only claim authorised in the EU concerns the protection of blood lipids from oxidative stress under the stated conditions. Further health claims are not permitted, and a single substance does not replace a balanced way of eating.

Hydroxytyrosol within the Mediterranean diet

The actual appeal of hydroxytyrosol lies in the fact that it is not an isolated laboratory product, but a natural component of a traditional food. The Mediterranean diet, in which high-quality olive oil plays a central role, is regarded professionally as an example of a well-balanced dietary pattern. It is rich in vegetables, fruit, legumes, nuts and fish, and olive oil is the preferred fat source within it. Hydroxytyrosol is, so to speak, a bonus of this fat source.

Anyone who wants to bring olive polyphenols into everyday life therefore does not necessarily have to reach for a preparation. A spoonful of good extra virgin olive oil over salad, oven vegetables or a soup is often enough to benefit from it regularly, within the framework of the authorised claim. Important is that the oil is stored cool and dark and not unnecessarily strongly heated, so that the sensitive polyphenols are retained. In this way, enjoyment combines with a conscious handling of the valuable ingredients of the olive.

Frequently Asked Questions (FAQ)

What is hydroxytyrosol?

Hydroxytyrosol is a natural polyphenol from the group of phenolic alcohols, which occurs above all in olives, olive leaves and extra virgin olive oil. It forms, among other things, during the breakdown of the bitter compound oleuropein.

Which authorised EU claim exists?

Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress. This claim applies only to olive oil with at least 5 mg of hydroxytyrosol and derivatives per 20 g of oil and a daily intake of 20 g.

Where does hydroxytyrosol occur?

The most important everyday source is high-quality extra virgin olive oil, as well as whole olives and olive leaves. The content fluctuates depending on variety, degree of ripeness, production and storage of the oil.

How much olive oil does the claim refer to?

The authorised claim refers to a daily intake of 20 g of the correspondingly polyphenol-rich olive oil, which corresponds to about two tablespoons. Only under these conditions may the claim be used.

Are food supplements with hydroxytyrosol necessary?

Anyone who regularly uses high-quality olive oil already takes in olive polyphenols through their food. Whether a preparation is sensible depends on the individual diet. For questions, medical advice is recommended.