Hydroxytyrosol - Tyrosol: Potent olive polyphenols, properties and human health

health polyphenols olives record

The Mediterranean Diet, followed in Greece for centuries, is a modern object of study and analysis. Its main ingredients are olive oil and table olives. It is now characterized as a diet with an extremely positive effect on human health. (Journal of Agricultural and Food Chemistry. 60 (29): 7081–95).

Mediterranean populations appear to have low rates of chronic degenerative diseases, cardiovascular disease, type 2 diabetes and highly improved cognitive function, as confirmed by a large number of tests and epidemiological studies (Molecules 2019, 24 (10), 2001).

Consumption of extra virgin olive oil and table olives, key ingredients of the Mediterranean diet, offers significant benefits to human health. Their positive effect, based on modern research studies, is attributed mainly to polyphenols, and more specifically to phenols such as hydroxytyrosol and tyrosol (BioFactors 2017, 43, 17–41., . Int. J. Mol. Cell. Med. 2016, 17, 843–871).

Tyrosol and hydroxytyrosol

tyrosol and hydroxytyrosol

Olive products (mainly table olives and olive oil) are classified in medical foods due to their nutritional benefits and protective properties against cardiovascular disease, age-related diseases, neurodegenerative disorders and others diseases. The main contributors to these properties are phenolic compounds such as hydroxytyrosol, tyrosol and oleuropein (Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 49(2), 12394).

Tyrosol and hydroxytyrosol are two characteristic phenolic compounds present in olives as free or conjugated forms as secoroids or aglycones.

Tyrosol is an extremely stable compound, which prevents the oxidation of "bad" LDL cholesterol, a fact that is of particular importance, given that this oxidation is one of the main stages in the process of atherosclerotic damage (Drugs Exp Clin Res. 2003;29(5-6):203-6).

Hydroxytyrosol is produced by the hydrolysis of oleuropein that occurs during olive ripening. Oleuropein accumulates in the leaves and fruits of the olive as a defense mechanism against pathogens and herbivores (Journal of Agricultural and Food Chemistry. 60 (29): 7081–95).

Antioxidant Capacity - Action

olive polyphenols

Oleuropein, tyrosol, hydroxytyrosol and squalene are some of the main antioxidants in olive products. These compounds, with the contribution of α-tocopherol (vitamin E) and oleic acid, clear free radicals and reduce oxidative damage and oxidative stress of aerobic organisms. This antioxidant and bactericidal action, as well as other vitamins and trace elements (mainly selenium) are extremely beneficial for human health (Tsilfoglou S., Petrotos K., Dissertation, 2016).

The ORAC (Oxygen Radical Absorbance Capacity) index measures the antioxidant capacity of foods based on their antioxidant power.

orac values polyphenols antioxidants english olives
The table shows that hydroxytyrosol is a powerful natural antioxidant as its potency is 13 times greater than that of ascorbic acid (vitamin C), about 4 times greater than grape seed extract and more than 3 times greater than epicatechin (green tea). Hydroxytyrosol is generally considered to be the most potent natural antioxidant (www.polyhealth.gr; Molecular Nutrition & Food Research, Volume 57, Issue 5, pages 760-771, EFSA Journal,2011).

In general, polyphenolic antioxidants have the ability to scavenge free radicals and reduce certain chelating reactions: reactive oxygen species (free radicals) must be removed from cells continuously to maintain proper metabolism. Research to date has shown that polyphenolic antioxidants can reduce inflammatory effects (such as coronary heart disease), delay the aging process, and protect proteins and DNA (Tsilfoglou S., Petrotos K., Dissertation, 2016).

Health Claim and polyphenols

polyphenols efsa

Hydroxytyrosol and its derivatives have been officially recognized by the European Food Safety Authority (EFSA) for their beneficial action. According to research published in the EFSA journal, the consumption of hydroxytyrosol and other polyphenols produced by olives and olive oil provide protection to blood lipids from oxidation, a damage known to affect cardiovascular health.

European Regulation 432/2012 states the Health Claim "Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress ". This health claim applies to olive oils containing at least 5 mg of hydroxytyrosol and its derivatives (eg oleuropein and tyrosol complex) per 20 g of olive oil (EU REGULATION No 432/2012).

Tyrosol - Hydroxytyrosol: Biological action and effect on health

table olive polyphenols effect health human

It should be noted that olive polyphenols are considered safe compounds, based on modern scientific research and data. For example, hydroxytyrosol is considered an extremely safe compound as it has not been found to be mutagenic or genotoxic even in high concentrations after in vivo testing (EFSA J. 2017 Mar; 15(3))

In recent years, oleuropein and some other polyphenols such as tyrosol, hydroxytyrosol and their various derivatives have been studied in terms of their pharmacological action, in particular their antioxidant, bactericidal and bacteriostatic action, as well as the reduction of blood platelet aggregation (Phytochemistry 28:67-69, 1989).

Many of the health benefits of table olives, reported in numerous studies, are directly related to hydroxytyrosol levels (J Agric Food Chem. 2012 Jul 25;60(29)).

The following are some of the effects of hydroxytyrosol, based on scientific studies:

• Hydroxytyrosol appears to have a wide range of biological effects, cardioprotective, anticancer, neuroprotective, antimicrobial and others (Molecules. 2019 May; 24 (10): 2001).

• Hydroxytyrosol can play an important protective role against ROS that cause oxidative damage to human cells. (Mol. Nut. Food Res., 53. 609-616).

• Hydroxytyrosol and oleuropein, as the main polyphenols in olives, which are a key component of the Mediterranean diet, lead to a relatively small number of coronary heart disease and certain cancers (Atheroscler Rep, 3 (1): 64-67).

• Hydroxytyrosol inhibits arachidonic lipoxygenase activity. It is worth noting that lipoxygenases are enzymes that catalyze the dioxygenation of fatty acids in lipids (Biosci Biotechnol Biochem. 1997 Feb; 61 (2): 347-5).

• Hydroxytyrosol appears to reduce endothelial cell degeneration (Arch Biochem Biophys. 2012 Nov 15; 527 (2): 81-9).

• Hydroxytyrosol appears to have hypolipidemic and anticoagulant activity (J. Agric. Food Chem. 2008, 56, 7872–7876; N Engl J Med. 2017 Sep 28; 377 (13): 1217-1227).

• Hydroxytyrosol, after extensive research, exhibits neuroprotective activity (Molecules 2015, 20, 4655–4680).

• Hydroxytyrosol can help with conditions such as rheumatoid arthritis, autoimmune diseases with chronic inflammation and osteoarthritis (Molecules 2016, 21, 1734–1746, J. Vet. Med. Sci. 2018, 80, 1801–1807, J. Funct . Food 2017, 36, 27–33, Biochim. Biophys. Acta-Gen. Subj. 2016, 1860, 1181–1191).

The following are some of the effects of tyrosol, based on scientific studies:

• Tyrosol exhibits bactericidal activity against staphylococcal, pseudomonas, enterococci and E. coli strains (J Food Prot. 2009 Dec; 72 (12): 2611-4).

• Tyrosol, based on extensive research, exhibits neuroprotective activity (Molecules 2015, 20, 4655–4680).

• Tyrosol has a beneficial effect on hypertension, atherosclerosis, coronary heart disease and obesity (J. Funct. Food 2019, 53, 93–104).

• Tyrosol exhibits anti-atherosclerotic activity (J. Nutr. Biochem. 2006, 17, 429–445).

• Tyrosol prevents osteopenia due to its antioxidant activity (J. Agric. Food Chem. 2008, 56, 9417–9422).

• Tyrosol and oleuropein inhibit the oxidation of LDL cholesterol, as they can bind free radicals or act as chelating agents, thus disrupting the peroxidation chain. (Lipids Jun, 35 (6): 633-8; Nutr Metab Cardiovasc. Dis., 9 (3): 102-107).

Polyphenol levels (tyrosol - hydroxytyrosol) in table olives

The Faculty of Pharmacy of the Department of Pharmacognosy and Natural Products Chemistry of the National and Kapodistrian University of Athens, under the auspices of the World Olive Center for Health and under the supervision of Professor Mr. Magiatis Prokopios, has carried out a variety of analyzes on commercially available samples of table olives. These analyzes were performed based on the NMR (Nuclear Magnetic Resonance) method.

According to these measurements, the average values of hydroxytyrosol and tyrosol found in commercial olives are 244 and 134 mg / kg respectively. (J. Agric. Food Chem. 2010, 58, 46–50).

High levels of polyphenols (hydroxytyrosol - tyrosol) in the table olives by Sakellaropoulos Organic Farms

sakellaropoulos olives polyphenols tyrosol

The table olives by Sakellaropoulos Organic Farms have systematically presented extremely high levels of tyrosol and hydroxytyrosol, based on NMR analyzes at the National and Kapodistrian University of Athens.

More specifically, the Kalamata table olives by Sakellaropoulos Organic Farms presented the highest values of tyrosol (930 mg / kg) and hydroxytyrosol (2100 mg / kg) combined (3030 mg / kg) compared to all the table olives that have been analyzed to date.

Tyrosol and hydroxytyrosol levels are 800% higher than the average of commercial olive samples (134 and 244 mg / kg respectively) that were included in the study performed at the University of Athens and published in J. Agric. Food Chem. 2010, 58, 46–50.

Therefore, the daily consumption of just 2 grams of these olives by Sakellaropoulos Organic Farms, provide more than 5 mg of hydroxytyrosol, tyrosol or their derivatives and corresponds to the consumption of 20 gr of olive oil belonging to the oil category that protect the blood lipids from oxidative stress, according to the EU regulation 432/2012.

Clinical studies of the effect of Kalamata olives by Sakellaropoulos Organic Farms on human health

table olive polyphenols effect health human tyrosol hydroxytyrosol Sakellaropoulos Organic Farms

This is the main reason that these olives have been selected to exclusively participate in two clinical studies, on their positive effect on human health, under the auspices of the World Olive Center for Health and the laboratory of Pharmacognosy and Natural Products Chemistry of the faculty of Pharmacy of the University of Athens. 

The results of the first clinical study, conducted from 2014 to 2016, were announced at the Oleocanthal International Society Conference (OIS) in June 2016, regarding the positive effect of the daily consumption of Kalamata type olives on the lipidemic profile of healthy volunteers and in particular on the LDL / HDL cholesterol ratio and the protection of the cardiovascular system.According to analysis carried out by the University, the Kalamata olives by Sakellaropoulos Organic Farms were found to have more than 5 times higher phenolic concentration compared to the average values. The daily consumption refers to a quantity of five (5) Kalamata table olives by Sakellaropoulos Organic Farms per day (Heart diseases & cholesterol: could olive consumption prevent them? - Dr. M.S. Katsarou).

In the second clinical study, conducted from 2017 to 2021, which is currently concluded and is about to be announced, the table olives by Sakellaropoulos Organic Farms have also been exclusively selected. More than 100 patients have volunteered for the study regarding the regulation of cholesterol. The impressive results of this clinical trial, made it possible for the research team to convert the organic table olives of Sakellaropoulos organic farms in the form of encapsulated powder, for their beneficial effect in the regulation of cholesterol levels, with an international patent (The olives that reduce cholesterol & olive powder in capsules - UOA Study).

In addition, the organic Kalamata table olives by Sakellaropoulos Organic Farms participate exclusively in the new OLIVES FOR HEALTH research project at Yale University in the United States Researchers from the Yale School of Public Health in the United States, in collaboration with researchers from the Department of Cardiology at Yale School of Medicine, undertaking a new research project on the human health benefits associated with daily consumption of table olives. The Olives for Health research project is carried out in the framework of the activities related to the establishment of the proposed Yale Olive Sciences and Health Institute (YOSHI).

Nick Sakellaropoulos
Chemical Engineer M.Sc.
Production Manager
Sakellaropoulos Organic Farms


EUR-Lex - 32012R0432

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Heart diseases & cholesterol: could olive consumption prevent them? - Dr. M.S. Katsarou - Video - Τελευταία πρόσβαση 17/12/2021

The olives that reduce cholesterol & olive powder in capsules - UOA Study - Video - Last accessed 17/12/2021